The 29th International Nuclear Physics Conference (INPC 2025)

25 May 2025, 08:00 → 30 May 2025, 20:00 Asia/Seoul

Daejeon Convention Center (DCC)

Kevin Insik Hahn, Byungsik Hong, Yeongduk Kim

The 29th International Nuclear Physics Conference (INPC 2025) will be held in Daejeon, Korea on May 25-30, 2025. It is hosted by the Center for Exotic Nuclear Studies (CENS) and the Center for Underground Physics (CUP) at the Institute for Basic Science (IBS) and the Center for Extreme Nuclear Matters (CENuM) at Korea University. The INPC series is overseen by the International Union of Pure and Applied Physics (IUPAP).

The scientific program will cover the following topics:

• Nuclear Structure
• Nuclear Reactions
• Hot and Dense Nuclear Matter
• Fundamental Symmetries and Interactions in Nuclei
• Hadron Structure and Reactions
• Nuclear Astrophysics
• Neutrinos and Nuclei
• Hadrons in Nuclei
• Applications Based on Nuclear Physics
• New Facilities and Instrumentation
• Quantum Computing and Artificial Intelligence in Nuclear Physics
• Outreach and Science Education 

INPC 2025 Circular

• [INPC 2025] 1st Circular.pdf
• [INPC 2025] 2nd Circular.pdf
• [INPC 2025] 3rd Circular.pdf
• [INPC 2025] 4th Circular.pdf
• [INPC 2025] Final Circular.pdf

Sunday, 25 May

Registration

Welcome Reception

Monday, 26 May

Opening Ceremony

Convener: Kevin Insik Hahn (Center for Exotic Nuclear Studies, IBS)

Keynote Session

Convener: Dong Pil Min (Seoul National University)

1 Nuclear physics - a driving force of the Universe

Nuclear processes are the driving force for the origin of the elements in the Universe and for the dynamics of the astrophysical objects which made them continuously until now. Tremendous progress in experimental and theoretical nuclear physics, paired with advances in astronomical observation and astrophysical modelling, has laid out the basic ideas how the elements have been and are being made. Despite this progress, some fundamental questions are still open. Here answers are hoped for from new experimental facilities getting operational around the world, but also from new observational tools.
The talk summarizes our current understanding and the perspectives of the origin of the elements from Big Bang nucleosynthesis, the emerging field of First Stars to solar and stellar nucleosynthesis and finally to explosive events like supernovae and neutron star mergers.

Speaker: Karlheinz Langanke (GSI Helmholtzzentrum Darmstadt)

presentation_ID712_Langanke.ppt

2 Status of the RAON Facility

The construction of the RAON (Rare isotope Accelerator complex for ON-line experiments) facility commenced in 2011 as part of the Rare Isotope Science Project (RISP). RAON is designed to produce stable and rare isotope beams for fundamental scientific research and application purposes.

The facility comprises two primary systems: an ISOL (Isotope Separation On-Line) system powered by a 70 MeV proton cyclotron and an IF (In-Flight Fragmentation) system driven by a heavy-ion superconducting linear accelerator. The low-energy section of the superconducting linac, SCL3, has been completed and commissioned. SCL3 also functions as a post-accelerator for ISOL beams. The high-energy section of the superconducting linac, SCL2, is under development and is designed to accelerate heavy ions to energies of up to 200 MeV/u.

The first phase of RISP, completed in 2022, included the construction of SCL3, cryoplant systems, the ISOL system with its cyclotron, supporting infrastructure, buildings, and seven experimental systems. Beam commissioning of SCL3 was conducted by accelerating Argon beams to 2.5 MeV/u using 22 QWR modules and subsequently to 18 MeV/u using 32 HWR modules. Argon beams were delivered to the KoBRA (Korea Broad Acceptance Recoil Spectrometer and Apparatus) experimental system for its commissioning.

The ISOL system was commissioned by bombarding a SiC target with proton beams, producing and identifying radioactive isotopes such as Na and Al. Subsequently, Na-25 was accelerated to 16 MeV/u and transported to KoBRA. Using a LaC2 target, the ISOL system generated and identified radioactive isotopes of Cs and Ba. The Collinear Laser Spectroscopy system (CLaSsy) was commissioned with Na-21 and Na-22 ISOL beams. Additionally, the NDPS (Nuclear Data Production System) and the MR-TOF (Multi-Reflection Time-of-Flight) Mass Measurement System are undergoing commissioning.

The first PAC meeting for domestic users in Korea was held in March 2024, marking the start of user services and operations in the summer of 2024. This presentation will provide an overview of the current status of the RAON facility and its experimental systems.

Speaker: Seung-Woo Hong (Institute for Rare Isotope Science, IBS)

683_HONG.pptx

10:30 Break

Plenary Session: 1

Convener: Marek Lewitowicz (GANIL)

3 Operation of the Facility for Rare Isotope Beams as a New User Facility

The Facility for Rare Isotope Beams (FRIB) at Michigan State University [1] took 14 years to design and establish and has operated as a new user facility since May 2022. More than 400 rare isotope beams have been delivered in the past three years for experiments, supporting an international user community of 1,800 scientists. FRIB is based on a superconducting heavy-ion linear accelerator capable of accelerating heavy-ion beams to energies of more than 200 MeV/nucleon with beam power up to 400 kW. Experiences, challenges, and opportunities from the first three years operating FRIB as a new user facility will be discussed.

The operation of FRIB as a user facility for the U.S. Department of Energy, Office of Science, Office of Nuclear Physics is supported under Award Number DE-SC0023633.

[1] J. Wei, H. Ao, B. Arend, S. Beher, G. Bollen, N. Bultman, F. Casagrande, W. Chang, Y. Choi, S. Cogan, C. Compton, M. Cortesi, J. Curtin, K. Davidson, X. Du, K. Elliott, B. Ewert, A. Facco, A. Fila, K. Fukushima, V. Ganni, A. Ganshyn, J. Gao, T. Glasmacher, J. Guo, Y. Hao, W. Hartung, N. Hasan, M. Hausmann, K. Holland, H. C. Hseuh, M. Ikegami, D. Jager, S. Jones, N. Joseph, T. Kanemura, S.-H. Kim, P. Knudsen, B. Kortum, E. Kwan, T. Larter, R. E. Laxdal, M. Larmann, K. Laturkar, J. LeTourneau, Z.-Y. Li, S. Lidia, G. Machicoane, C. Magsig, P. Manwiller, F. Marti, T. Maruta, A. McCartney, E. Metzgar, S. Miller, Y. Momozaki, D. Morris, M. Mugerian, I. Nesterenko, C. Nguyen, W. O’Brien, K. Openlander, P. N. Ostroumov, M. Patil, A. S. Plastun, J. Popielarski, L. Popielarski, M. Portillo, J. Priller, X. Rao, M. Reaume, H. Ren, K. Saito, M. Smith, M. Steiner, A. Stolz, O. B. Tarasov, B. Tousignant, R. Walker, X. Wang, J. Wenstrom, G. West, K. Witgen, M. Wright, T. Xu, Y. Xu, Y. Yamazaki, T. Zhang, Q. Zhao, S. Zhao, K. Dixon, M. Wiseman, M. Kelly, K. Hosoyama, S. Prestemon, “Accelerator commissioning and rare isotope identification at the Facility for Rare Isotope Beams”, Modern Physics Letters A Vol. 37, No. 09 (2022) 2230006 (11 pages) (World Scientific Publishing Company) DOI: 10.1142/S0217732322300063

Speaker: Thomas Glasmacher (Michigan State University, East Lansing, MI, USA)

Presentation_ID746_Glasmacher.pdf.pdf

4 Progress of Nuclear Research Center in Huizhou -2025

Main researches of Nuclear Research Center in Huizhou are nuclear physics, few topics of foundation physics, interdisciplinary, carbon neutralization energy based on accelerator driven advanced nuclear energy system and the precision radiotherapy. There are two national mega-scale scientific facilities: Highly Intensive Accelerator Facility (HIAF 2018~2025) and Chinese Initial Accelerator Driven System (CiADS 2021~2027) are under constructing in plan. HIAF accelerates the ions from proton to uranium with intensities 5x1013/ppp ~1011/ppp ranging GeV/A, CiADS is 10MW system, which consists a 2.5MW proton beam power SCL, >2.5MW spallation target and the 7.5MW blanket and few experimental terminals.
Now, the main HIAF accelerator has been installed and start tuning beam. CiADS’s SCL is installing, which prototype have been using SHE operation with >93% beam availability for 2 years.
This international center will provide great research opportunities on intensive RIB when using CiADS to produce the highest ISOL RIB and post-accelerate by HIAF, High Energy Density Physics driven by ~100kJ/ppp Bi beam, and Muon Physics & Application by intensive muon beam. HIAF power will be updated to ~MJ/ppp, CiADS power will be updated ~10MW SCL and conjunction HIAF+CiADS in future 10~15 years.

Speaker: Prof. Wenlong Zhan (Institute of Modern Physics, CAS, China)

HIAF及治癌.pptx

Progress of Nuclear Research Center in Huizhou- 2025.pdf

5 The RIBF Facility Upgrade Project

We introduce the facility upgrade project of "Radioactive Isotope Beam factory" (RIBF). The project was discussed extensively in 2022-2023, and the discussions were summarized in a report [1]. RIKEN started experimental programs with fast radioactive isotope (RI) beams at an inflight separator RIPS in 1990 [2]. RIPS was designed to give intense RI beams for reaction studies. Indeed, the intense beams encouraged developments of several experimental methods to study the nuclear structure via reactions. Because of high demands to access more neutron-rich nuclei and more heavier nuclei, the RIBF facility was constructed in 2006. Combination of the superconducting cyclotron SRC and an inflight separator BigRIPS has produced more than 170 new isotopes and has contributed to nuclear physics with programs at three spectrometers for shell evolution, the r-process path nucleosynthesis, nucleon-nucleon correlation in the vicinity of the drip lines, and equation of state in asymmetric nuclear matter. Excellent achievements have been made under international collaborations up to the region of medium mass region. The RIBF upgrade aims to access a heavier mass region where interplay between strong force and Coulomb force becomes dominant, and discover new quantum phenomena associated with the interplay.
In this talk, We present the history of developments for fast RI beams at RIPS as well as RIBF, and show recent achievements obtained at RIBF. Special emphasis is given to recent highlights. We discuss the upgrade project.

[1]https://www.nishina.riken.jp/researcher/RIBFupgrade/RIBF_Upgrade_NCAC.pdf
[2]T.Kubo et al., Nucl. Instrum. Meth. B 70, 309 (1992).
[3]Y.Yano, Nucl. Instrum. Meth., B {\bf 261}, 1009 (2007).

Speaker: Hiroyoshi Sakurai (RIKEN Nishina Center for Accelerator-Based Science)

INPC-2025-sakurai.pptx

6 The science and status of the Electron Ion Collider (EIC) at BNL

After twenty five glorious years of discovery followed by detailed study of Quark Gluon Plasma, the Relativistic Heavy Ion Collider (RHIC) at BNL will cease its operation in 2025. An electron beam facility will be added to the accelerator complex - in partnership between BNL and Jefferson Lab - to convert the RHIC into a high-luminosity high-energy polarized electron-proton (-light ion) and -heavy ion collider - The Electron Ion Collider (EIC). The EIC will allow scientists an unprecedented study of the role of gluons in QCD, for example, to study of the partonic origin of mass and spin of a proton and it will allow (arguably) the cleanest way to explore existence of a novel form of gluon matter known as Color Glass Condensate (CGC) predicted in QCD. All of these together are critical to understanding mechanism of color confinement in QCD. At the highest energy the EIC also presents an opportunity to explore precision electroweak and beyond-the-Standard Model (SM) Physics complementary to the LHC. EIC will be built in the next ten years and will operate starting mid-2030's. An international electron-Proton Ion Collider (ePIC) detector collaboration is leading the design and construction of the detector. I will summarize the science and status of the EIC and outlook towards its realization.

Speaker: Abhay Deshpande (Stony Brook University & BNL)

Presentation ID739 Deshpande.pdf

Presentation ID739 Deshpande.pptx

13:00 Lunch

Parallel Session: 1_Applications Based on Nuclear Physics

Convener: Ulli Köster

7 Production of innovative medical radionuclides by mass separation

Nuclear medicine has seen a fast growth in the last few years through the approval of novel therapy drugs based on ¹⁷⁷Lu for endocrine and prostate cancers - namely Lutathera and Pluvicto - or the first drug for alpha therapy with ²²³Ra - Xofigo. Those new developments have also opened the door for theranostic applications, where interchanging radionuclides enables to validate the targeting vector via nuclear imaging before proceeding through with therapy.
However, most promising radionuclides for theranostic applications are not yet available commercially and their production routes are sometimes challenging. Thanks to the mass separation of isotopes, as applied at the CERN ISOLDE and MEDICIS facilities, it is possible to offer a broad catalogue of radionuclides to support medical research. In particular, the MEDICIS is being entirely operated for that purpose, separating radionuclides produced at CERN, as well as some produced externally at high-flux nuclear reactors like ILL or SCK CEN, or high-intensity proton irradiation facilities like ARRONAX or PSI. These facilities are federated around PRISMAP, the European medical radionuclide programme.
In this contribution, I shall present the use of mass separation to support medical radionuclide research, some of the recent developments at CERN, and how it coalesce within the PRISMAP consortium.

Speaker: Thomas Elias Cocolios (KU Leuven, IKS)

Presentation_ID680_Cocolios.pdf

Presentation_ID680_Cocolios.pptx

8 Radiation therapy at TRIUMF: medical applications of nuclear physics

Besides being Canada's particle accelerator centre with emphasis on nuclear, particle and accelerator physics, TRIUMF has a long history of medical isotope production and radiotherapy. Cancer treatment with different particles has been a long-standing commitment at TRIUMF, first with pion therapy and then with proton therapy, for many years operating Canada's only proton therapy facility. To improve treatment further, we are researching and establishing FLASH radiotherapy, where the total treatment dose is delivered in less than a second. In addition, we are investigating using alpha and auger emitters for targeted radioisotope therapy. Both have the potential to revolutionize cancer treatment by increasing the therapeutic index.

Speaker: Cornelia Hoehr (TRIUMF)

Presentation_ID320_Hoehr.pdf

9 Positron-Emitting Beams in Hadron Therapy: Insights from Recent Studies at GSI

Without real-time dose conformity feedback during treatment, ion beam therapy relies heavily on the accuracy of treatment planning systems. However, anatomical changes in patients can occur between treatment planning and irradiation, or even during treatment, necessitating the addition of safety margins around the target area to ensure adequate coverage despite these uncertainties. Therapeutic ion beams composed of positron-emitting isotopes of carbon and oxygen hold significant potential for advanced cancer treatments by combining therapeutic effectiveness with the added capability of in-beam positron emission tomography (PET) for image-guided hadron therapy. A series of experimental studies conducted at GSI, Darmstadt, Germany, under the ERC-funded project Biomedical Application of Radioactive Beams (BARB), investigated the prospects and challenges of image-guided hadron therapy using positron-emitting isotopes of carbon and oxygen. GSI is uniquely positioned to advance the development of precise, image-guided cancer therapies using positron-emitting therapy beams. Its versatile Fragment Separator (FRS) and extensive expertise in radioactive ion beams, biophysics, dosimetry, and radiobiology provided a robust foundation for this work. Secondary beams of positron emitters were produced and separated in-flight via fragmentation using the FRS with the established Bρ-ΔE-Bρ technique and subsequently delivered for imaging and biomedical experiments. These studies explored both physical and biological aspects, including the inflight production and separation of radioactive ion beams (RIB), the interplay between half-life, production cross-section, and measurement time, and demonstrated precise dose delivery with minimal toxicity in the treatment of a mouse osteosarcoma. Key results from the BARB project will be presented.

Speaker: Dr Sivaji Purushothaman (GSI Helmholtzzentrum für Schwerionenforschung GmbH)

Presentation_ID690_Purushothaman.pptx

10 A new charge-reset method for determining Auger-electron emission multiplicities

Targeted internal radiotherapy and patient-specific treatment is of great importance for treating advanced staged cancers, allowing for personalised radiotherapeutics to be deployed to treat otherwise unresponsive cancers. Within the radiotherapeutic armoury, Auger-electron therapy is of particular interest since the low-energy electrons deposit their energy over short distances (on the scale of nm-$\mu$m), resulting in a high linear energy transfer (LET), and allowing for precise targeting of cancerous cells [1, 2]. Auger electrons are emitted during atomic relaxation following the creation of a vacancy in an inner-atomic shell, for example, following electron capture decay or internal conversion. During the entire relaxation process multiple Auger electrons can be emitted into the surrounding environment. For determining the impact of Auger electron emission, precise nuclear data measurements are required, not just for the energy of the emitted electrons, but also the multiplicity, i.e. the average number of electrons emitted.

A new charge-reset method has been developed for determining emission multiplicities of Auger electrons following the creation of a vacancy in an inner-atomic orbital. Excited states are populated through below-barrier Coulomb excitation reactions. The de-excitation of states by internal conversion will then trigger a series of Auger cascades, increasing the charge state of the ion. The distribution of charge states can be measured by passing the ions through an electromagnetic spectrometer. The addition of a charge reset foil, placed between the target and the spectrometer, resets the atomic charge state of scattered ions to a nominal value. An internal conversion that occurs after the reset foil then induces an Auger cascade and so affects the distribution of charge states measured by the electromagnetic spectrometer. Here, I will present initial results, using the FMA+GRETINA setup at Argonne National Laboratory, to determining Auger-electron emission multiplicities in $^{177}$Hf, daughter of $^{177}$Lu.

References
[1] B. Cornelissen and K. A. Vallis, Targeting the Nucleus: An Overview of Auger-Electron Radionuclide Therapy. Current Drug Discovery Technologies, 7(4):263–279, 2010.
[2] A. Ku, V. J. Facca, Z. Cai, and R. M. Reilly, Auger electrons for cancer therapy - a review. EJNMMI Radiopharmacy and Chemistry, 4(1):27, 2019

Speaker: Jacob Heery (University of Surrey)

Presentation_ID229_Heery.pdf

Parallel Session: 1_Fundamental Symmetries and Interactions in Nuclei

Convener: Young-Ho Song (RISP, IBS)

11 Search for Axion-Like-Particles in $\eta$ meson decays with the HADES Detector

The High-Acceptance Di-Electron Spectrometer (HADES) operates at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, using pion, proton, and heavy-ion beams provided by the SIS-18 synchrotron [1]. In February 2022, the HADES Collaboration measured proton-proton collisions at 4.5 GeV momentum using the upgraded setup as part of the FAIR-Phase0 program [2]. One of the key objectives of the HADES physics program is to test the predictions of the Standard Model and search for potential hints of new phenomena beyond current theoretical frameworks (BSM – Beyond Standard Model Physics). It can be experimentally accessible via particles in the MeV–GeV mass range, which are coupled to the Standard Model.

Recently, a new set of calculations were done which predicts a possible existence of Axion-Like-Particles with a mass $m_a = \mathcal{O}(1 - 100)\ \mathrm{MeV}$ and $f_a = \mathcal{O}(1 - 10)\ \mathrm{GeV}$ [3] with additional PQ-breaking contribution to their masses. In particular, by studying $\eta$ meson decays into dilepton ($e^+e^-$) channels, we investigate the possible existence of an Axion-Like Particle (ALP) [4-5] In this scenario, an intermediate state of the $\eta$ meson decay could involve the creation of a new particle through the sequence $\eta \rightarrow \pi^+ \pi^- a ( \rightarrow e^+ e^- )$. The particle is hypothesized to be an iso-scalar or axial-vector gauge boson, which may mediate a fifth force with couplings to Standard Model particles [6].

These studies are further motivated by observed anomalies in the invariant mass distribution of $e^+e^-$ pairs in isoscalar magnetic nuclear transitions of $^8\mathrm{Be}$ and $^4\mathrm{He}$ nuclei [7-8]. These anomalies have been interpreted as evidence for the creation and decay of an intermediate particle with a mass of approximately $17\ \mathrm{MeV}/c^2$, and suppressed mixing with the neutral pion.

In this talk, we will discuss the general motivations for ALP studies, present our analysis methodology, and share preliminary results from data collected using the high-resolution HADES spectrometer.

Bibliography:
[1] G. Agakichiev et al. (HADES Coll.), Eur. Phys. J. A 41, 243 (2009).
[2] J. Adamczewski-Musch et al. (HADES Coll.) Eur. Phys. J. A 57, 138, 4 (2021).
[3] D. S. M. Alves and N. Weiner, JHEP 07, 092 (2018).
[4] D. S. M. Alves, Phys. Rev. D 103, 055018 (2021)
[5] D. S. M. Alves and S. Gonzalez-Solis, JHEP 07, 264 (2024).
[6] J. L. Feng et al., Phys. Rev. Lett. 117, 071803 (2016).
[7] A. J. Krasznahorkay et al., Phys. Rev. Lett. 116, 042501 (2016).
[8] A. J. Krasznahorkay et al., Phys. Rev. C 104, 044003 (2021).

Speaker: Marcin Zielinski (Jagiellonian University in Krakow)

Presentation_ID623_ZIELINSKI.pdf

12 Highly-Charged Radioactive Molecules: Amplifying Sensitivity for New Physics

One necessary extension to the Standard Model of Particle Physics (SM) [1-4] is one which describes the behaviour of the early universe that leads to the matter-antimatter asymmetry [5] which we observe today. It is commonly assumed that any explanation of this matter-antimatter imbalance must rely on the violation of the combined symmetry of charge conjugation (C) and parity (P) [6] that is presently, however, considered to be too weak in the SM. Thus, identifying a new source of CP violation is of critical importance. CP-violating effects, particularly those that originate within the atomic nucleus, can be investigated by combining precision techniques from atomic, molecular, and optical physics with rare isotopes produced at accelerator facilities such as TRIUMF in Canada [7]. In searches for CP-violating nuclear Schiff moments, for example, molecular systems offer a sensitivity advantage of 3-4 orders of magnitude [8-10] which can be further increased by up to a factor of 1000 when a radioactive, octopole-deformed nucleus is incorporated into the molecule [11]. Among these radionuclides, the short-lived protactinium isotope $^{229}$Pa is thought to exhibit the highest sensitivity, once a suitable molecule has been identified. Recently, triply charged protactinium-monofluoride PaF$^{3+}$ has been proposed as a highly attractive probe [12], which is isoelectronic to the well studied case of neutral RaF [13]. Experimentally, forming such 'highly charged' molecules remains a significant challenge, also because all other Pa isotopes are radioactive, complicating the development of the necessary techniques. In this talk, we present the experimental formation of stable, doubly-charged cerium monofluoride CeF$^{2+}$ which is identified as an intriguing surrogate to PaF$^{3+}$ with a very similar molecular structure. Specific sensitivities of CeF$^{2+}$ to new physics also position the system as an interesting probe for disentangling sources of symmetry-violating behaviour inside the nucleus.

References

[1] S. L. Glashow. Partial-symmetries of weak interactions. Nuclear Physics, 22:579–588, 1961.

[2] S. Weinberg. A model of leptons. Physical Review Letters, 19:1264, 1967.

[3] A. Salam. Weak and electromagnetic interactions. Proceedings of the Eighth Nobel Symposium, pages 367–377, 1968.

[4] M. Veltman. Regularization and renormalization of gauge fields. Nuclear Physics B, 44:189–213, 1972.

[5] L. Canetti, M. Drewes, and M. Shaposhnikov. Matter and antimatter in the universe. New Journal of Physics, 14:095012, 2012.

[6] A.D. Sakharov. The initial stage of an expanding universe and the appearance of a nonuniform distribution of matter. Soviet Physics JETP, 22:241, 1966.

[7] J. Dilling, R. Krücken, and G. Ball. Isac overview. Hyperfine Interactions, 225:1–8, 2014.

[8] N.J. Fitch, J. Lim, E.A. Hinds, B.E. Sauer, and M.R. Tarbutt. Methods for measuring the electron’s electric dipole moment using ultracold ybf molecules. Quantum Science and Technology, 6(1):014006, 2020.

[9] ACME Collaboration, V. Andreev, D.G. Ang, D. DeMille, J.M. Doyle, G. Gabrielse, J. Haefner, N.R. Hutzler,Z. Lasner, C. Meisenhelder, B.R. O’Leary, C.D. Panda, A.D. West, E.P. West, and X. Wu. Improved limit on the electric dipole moment of the electron. Nature, 562:355–360, 2018.

[10] T.S. Roussy, L. Caldwell, T. Wright, W.B. Cairncross, Y. Shagam, K.B. Ng, N. Schlossberger, S.Y. Park, A. Wang, J. Ye, and E.A. Cornell. An improved bound on the electron’s electric dipole moment. Science, 381(6653):46–50, 2023.

[11] R.G. Garcia Ruiz. Short-lived radioactive molecules: A sensitive laboratory for the study of fundamental symmetries. APS Division of Nuclear Physics Meeting Abstracts, 2019:KA–003, 2019.

[12] C. Zülch, R.F. Garcia Ruiz, S.M. Giesen, R. Berger, and K. Gaul. Cool molecular highly charged ions for precision tests of fundamental physics. Arxiv, arXiv: 2203.10333, 2022.

[13] S.M. Udrescu, S.G. Wilkins, A.A Breier, et al. Precision spectroscopy and laser-cooling scheme of a radium-containing molecule. Nature Physics, 20:202–207, 2024.

Speaker: Rane Simpson (TRIUMF)

Presentation_ID178_Simpson.pptx

13 The measurement of X17 boson anomaly: the n_TOF channel 3He(n,X17)

Significant anomalies have been observed in the relative angular emission of electron-positron pairs in the 7Li(p,e+e−)8Be, 3H(p, e+e−)4He and 11B(p,e+e−)12C nuclear reactions [1–3] that have been interpreted as the signature of a boson (hereafter referred to as X17) of mass MX17 = 16.8 MeV/c2. It has been proposed that the X17 could be a vector boson, mediator of a fifth “protophobic” force, i.e. characterized by a strong suppression of the coupling to protons compared to neutrons [4]. Under this assumption, the X17 discovery could explain, at least partially, the long-standing (recent) anomaly on the muon (electron) magnetic moment [5]. Till now, few experiment repeated the ATOMKI measurements, but still a clear confirmation (or rejection) of the existence of the X17 is pending. At n_TOF, we would like to measure a new reaction induced by neutrons (3He(n,X17) ) which produce the same *4He state produced by 3H(p,X17)4He. In this talk, after a brief presentation of the physics motivations, the new reaction will be analyzed, together with the ab initio calculations. The apparatus, designed to study such reaction at n_TOF facility, is based on a MPGD which works in TPC mode. The use of magnetic field, allow the reconstruction of the electron energy, charge and angle. In the detector R&D, particular care has been devoted to reduce the amount of material with a wide use of Crabon fiber to reduce the background produced by scattered neutrons as well as reducing the production of external pair creation.

[1] A. J. Krasznahorkay et al., Phys. Rev. Lett. 116, (2016) 042501.
[2] A. J. Krasznahorkay et al., Phys. Rev. C 104, (2021) 044003.
[3] A. J. Krasznahorkay et al., Phys. Rev. C 106, (2022) 061601.
[4] J. L. Feng, B. Fornal, I. Galon, S. Gardner, J. Smolinsky, T. M. P. Tait and P. Tanedo Phys. Rev. Lett. 117, (2016) 071803.
[5] L. Morel, Z. Yao, P. Cladè, S. Guellati-Khèlifa, Nature 588, (2020) 61.
[6] The MEG II collaboration: https://arxiv.org/pdf/2411.07994

Speaker: pierfrancesco mastinu (istituto nazionale di fisica nucleare- laboratori nazionali di Legnaro)

presentation_ID102_Mastinu.pptx

14 GBAR experiment : Classical freefall experiment of antihydrogen at rest in terrestrial gravitational field

The measurement of the gravitational acceleration of the antihydrogen in the terrestrial gravitational field is a test of the weak equivalence principle for antimatter and a measurement of the fundamental property of antimatter which was first measured by the ALPHA experiment with 27% precision in 2023. Efforts from a few competitions for better precision have been made. The GBAR experiment aims to measure gravitational acceleration below 1% by producing the world’s first ultra-cold antihydrogen based on antihydrogen ion cooling. The GBAR experiment has given deep R&D for ion production and the status of antihydrogen production with related CPT test will be reported.

Speaker: bongho kim (IBS)

Presentation_ID356_kim.pdf

Parallel Session: 1_Hadrons in Nuclei

Convener: Kazuo Tsushima (UNICID (University of City of Sao Paulo))

15 Antimatter in relativistic heavy-ion collisions

Recently, anti-hyperhydrogen-4, an antimatter hypernucleus, was discovered in relativistic heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) by the Solenoidal Tracker At RHIC (STAR). This is the heaviest antimatter (hyper)nucleus observed. This talk will review the discoveries of multiple antimatter nuclei and hypernuclei and the exploration of matter-antimatter symmetry in heavy-ion collisions over the past 15 years.

Speaker: Hao Qiu (Institute of Modern Physics, CAS)

Presentation_ID342_Qiu.pdf

16 Glauber scattering for photo-nuclear reactions of light vector mesons with the Regge amplitude for the subnuclear process

We study photoproduction of light vector mesons, $\rho^0$, $\omega$, and $\phi$ in nuclei by utilizing the Glauber scattering theory for photo-nuclear interactions. Avoiding ad hoc parameterizations of the scattering amplitude and the cross section frequently assumed in the conventional Glauber theory, the subnuclear processes, including vector meson photoproduction $\gamma N \to VN$ and subsequent elastic scattering $VN \to VN$ off nucleons, are described by the Reggeized meson exchange within the framework of the eikonal integral for the nuclear process.
Current theoretical calculations reproduce experimental results to a good degree, revealing that Pomeron exchange becomes dominant over the meson exchange in the energy region above the resonances, namely at $E_\gamma\geq3$ GeV, and that the transverse component of the nuclear cross section gives the contribution much larger than the longitudinal one by a factor of $10^{4}$. The application to the analysis of nuclear transparencies in the electromagnetic production of mesons in nuclei is presented, with the role of the shadowing discussed.

Speaker: Byung-Geel Yu (Korea Aerospace University)

Presentation_ID523_yu.pptx

17 Recent progress and prospects of kaonic nuclear bound states at J-PARC

In recent years, the possibility that an anti-kaon ($\bar K)$ could become a constituent particle of a nucleus has been widely discussed based on the strongly attractive $\bar KN$ interaction in the I = 0 channel. After many experimental efforts over the decades, we reported an observation of the simplest kaonic nuclear-bound state, $``K^-pp"$. We observed the state in the $\Lambda p$ invariant-spectrum of the in-flight $K^-$ reaction on helium-3 in the J-PARC E15 experiment[PLB789(2019)620, PRC102(2020)044002]. This $K^-$-induced reaction is indeed a good way to excite the sub-threshold $\bar K$, so we will proceed with further study of various kaonic nuclei at J-PARC.

One direction is to investigate heavier systems, such as a three-nucleon system $``K^-ppn"$. This state could be populated by simply replacing the helium-3 target with helium-4, but a neutron would be emitted as a decay particle. Another direction is to investigate the observed $``K^-pp"$ state in more detail. We will search for the iso-spin partner state $``\bar K^0 nn"$, and the spin-parity of the $``K^-pp"$ will be studied by means of a spin-spin correlation measurement between decay $\Lambda$ and proton. These studies, together with theoretical discussions, will further establish the existence of the kaonic nuclear-bound states and reveal their nature.

We are now constructing a new solenoid spectrometer having almost 4$\pi$(93\%) solid angle and much better neutron detection capability. The construction is to be completed in two years, and the first data-taking with a helium-4 target will start in 2027 as the J-PARC E80 experiment. Even before that, we recently obtained some datasets with a helium-4 target and additional helium-3 data with a partially upgraded setup of the E15.

In this contribution, we present the latest results from the existing E15 spectrometer. We also present the construction status of the new spectrometer and discuss future prospects with it.

Speaker: Tadashi Hashimoto (RIKEN)

Presentation_ID667_Hashimoto.pdf

Parallel Session: 1_Hot and Dense Nuclear Matter

Convener: Sangyong Jeon (McGill University)

18 Hyperon local polarization in heavy-ion collisions: experimental highlights

The observation of hyperon local polarization in nucleus-nucleus collisions has opened a new way to study the complex vortical structures and the fundamental properties of the QGP. In this talk, I will discuss recent experimental results from RHIC and LHC, as well as their implications on the understanding of spin polarization in hadronic collisions.

Speaker: Zhenyu Chen (Shandong University)

Presentation_ID353_Chen.pdf

19 Deciphering the spatial and spin structures of (anti-)hypertriton in heavy-ion collisions

The hypertriton($_\Lambda^3$H), a bound state of a proton, a neutron, and a $\Lambda$ hyperon, serves as a unique probe for studying hyperon-nucleon interactions and the behavior of strange quarks in dense nuclear matter. In heavy-ion collisions, the binding energy and spin of $_\Lambda^3$H have been experimentally measured, albeit with significant uncertainties. We propose a novel method to extract detailed information about their wave function by analyzing the production and transverse momentum ($p_T$) spectrum of (anti-)hypertritons using the coalescence model. Furthermore, light hypernuclei can also be polarized in non-central heavy-ion collisions, similar to unstable hadrons. We suggest that the global polarization of (anti-)hypertritons can be utilized to decipher their internal spin structures in heavy-ion collisions. This study not only provides a understanding of the spatial and spin structures of (anti-)hypertritons but also offers new insights into the dynamics of hyperon-nucleon interactions and the polarization mechanisms in heavy-ion collisions.

Speaker: Mr Dai-Neng Liu (Fudan University)

Presentation_ID534_LIU.pptx

20 Study of f_0(980) resonance production in pp collisions at √s = 13.6 TeV with ALICE

To investigate the characteristics of the hadronic phase in proton-proton (pp) and heavy-ion (AA) collisions, short-lived resonances serve as essential probes. Among them, the f₀(980) resonance, with a lifetime of approximately 3–5 fm/c as reported by ALICE, is particularly sensitive to re-generation and re-scattering processes in the hadronic phase, making it highly suitable for such studies. Moreover, its debatable internal structure, potentially corresponding to tetraquark states or meson-meson molecular states, remains of significant physical interest. In this study, f₀(980) resonance was analyzed using data collected with the ALICE detector in pp and p-Pb collisions at LHC energies. It was reconstructed via its main decay channel, π+π−, with a particular focus on identifying and reconstructing charged pions. The significant increase in statistics collected at LHC Run 3 enabled a more precise measurement, providing deeper insights into its properties. Furthermore, the production cross section and the ratio of this resonance to the stable hadron yields were studied, complementing the results already obtained in Run 2. This analysis discussed the internal structure of f₀(980) resonance and provides a valuable reference for understanding the properties of the possible hadronic phase in small collision systems.

Speaker: Yunseul Bae (Sungkyunkwan University (SKKU))

Presentation_ID408_Bae.pdf

21 Investigating the X(3872) as a $D\bar{D}^*$ Molecular State via Coalescence Model

Since the discovery of the X(3872) two decades ago, extensive experimental and theoretical efforts have aimed to clarify its internal structure. Two primary scenarios frequently discussed are a four-quark compact configuration $(u\bar{u}c\bar{c})$ and a $D\bar{D}^*$ molecular configuration. In this presentation, we focus on the two possibility $c\bar{c}g$ hybrid as well as $D\bar{D}*$ molecular structure of X(3872) as calculated using the coalescence model. Then, we calculate the transverse momentum distribution for each possibility and compare it with the X(3872) data measured by the CMS Collaboration.

Speaker: HyeongOck Yun (Yonsei university)

Presentation_ID609_Yun.pdf

Parallel Session: 1_New Facilities and Instrumentation

Convener: Adam Maj (IFJ PAN Krakow)

22 FRIB First Three Years of User Operations and Performance Ramp Up

The Facility for Rare Isotope Beams (FRIB) began user operations in May 2022 and has delivered more than 280 rare isotope beams to users, some of which were first-ever discoveries at FRIB. The facility features unique accelerator devices and capabilities, including: 1) the world’s largest heavy-ion superconducting (SC) linear accelerator, capable of accelerating uranium beam up to 200 MeV/u; 2) a large momentum acceptance fragment separator equipped with large-scale SC magnets; 3) a liquid lithium charge stripper. FRIB accelerator has been operating delivering more than 6000 hours of beam time annually, including approximately 4000 hours for rare isotope science and 2000 hours for industrial applications, with machine availability above 93%. In parallel with user operations, FRIB have been conducting the beam power ramp-up program. The maximum beam power achieved so far are 10.4 kW for uranium beams and 22 kW for lighter beams, with plans to upgrade beam intercepting devices, such as charge selector, target, and beam dump, to accommodate the ultimate 400 kW beam power. In this talk, the status of user operations will be presented with highlights of achievements in accelerator devices and beam acceleration. The plan for beam power ramp-up will also be discussed.

Speaker: Sang-hoon Kim (Facility for Rare Isotope Beams, Michigan State University)

Presentation_ID681_Kim.pdf

23 Status of the NUSTAR project at GSI/FAIR

The NUSTAR (NUclear STructure, Astrophysics, and Reactions) collaboration [1] aims to exploit the opportunities offered by the FAIR facility. The FAIR-0 experimental campaign, using detection systems built for the future facility, is ongoing at the existing GSI accelerator complex since 2021. Preparation for moving from the present experimental areas to the new facility have started. It is foreseen that the higher transmission of the Super-FRS separator and the higher primary beam intensities of the SIS-100 synchrotron will be exploited from around 2028 and 2029, respectively.

I will present recent scientific and technical highlights, as well as the details on the transition from the existing GSI to the FAIR facility.

[1] https://fair-center.de/user/experiments/nustar

Speaker: Zsolt Podolyak (University of Surrey)

INPC_may2025_Zsolt_Podolyak.pptx

24 Latest developments at GANIL/SPIRAL2

GANIL celebrated the 40th anniversary of its first experiment performed with the cyclotrons in 2023. Along these 40 years, constant developments and upgrades of the accelerator and experimental areas have allowed to perform experiments with radioactive beams produced by in-flight method with the LISE spectrometer and by ISOL method with SPIRAL1. Some selected examples of the latest experiments performed will be presented, together with the recent beam developments with SPIRAL1 target-ion sources, and the ambitious plan for a complete refurbishing of the facility which has recently been approved and funded.

The SPIRAL2 Phase 1 LINAC is now fully operational and three experimental campaigns were performed in 2022-2024 in the NFS (Neutron For Science) experimental hall. The components of S3 spectrometer are under test and a first beam was sent on the target at the end of 2024. Optical commissioning of the spectrometer is planned at the end of 2025. The construction of the DESIR hall for low-energy nuclear physics is in full swing and the first experiments are planned in 2027. The installation of the new LINAC injector optimized for A/Q=7 will start in 2025. The presentation will give an overview on these different achievements together with the vision for the medium and long term plans.

Speaker: Fanny Farget (GANIL)

GANILpresentation_INPC.pdf

25 Facilities and Research at iThemba LABS

The premier accelerator at iThemba LABS is the k=200 Separated Sector Cyclotron (SSC). It has been used in the past for nuclear physics research, radioisotope production, and hadron therapy. It will soon be augmented by the South African Isotope Facility (SAIF) with the acceptance of a recently acquired IBA C70 cyclotron that will be dedicated to the production of radioisotopes, principally $^{82}$Sr, $^{68}$Ge, and $^{22}$Na. This will mean that the main cyclotron of iThemba LABS, the SSC, will in future be free to be dedicated to research, although major on-going refurbishments are planned.

New instrumentation that will be available includes the GAMKA detector array, which replaces the existing AFRODITE array, and is equipped with up to 19 HPGe clover detectors, and an array of 21 large volume LaBr3 detectors (ALBA). These detectors can also be combined with the existing k=200 spectrometer for studies of e.g. giant resonances and strength functions. The β-decay tape station has also been upgraded to be able to accommodate up to eight clover detectors and a Si(Li) conversion electron detector.

iThemba LABS has a Low-Energy Radioactive-Ion Beam (LERIB) project to produce RIB’s of up to 60 keV energy using the Isotope Separation OnLine (ISOL) method. The target/ion-source “front-end” has been installed in an off-line test facility. It is the same as that employed in the SPES project[1] of INFN Legnaro, in Italy, which is derived from the ISOLDE front-end[2] at CERN. The off-line test facility is routinely producing surface-ionized stable beams. Funding is being sought to move the front-end to an online facility, which is called LERIB Phase 0. In the meantime, work on the offline facility includes the development of a forced electron beam-induced arc discharge (FEBIAD) ion-source, and the development of beams of radiobiological interest such as the isotopes of terbium.

[1] G de Angelis et al 2015 J. Phys.: Conf. Ser. 580 012014
[2] ed. Ames, J. Cederkall, T. Sieber, F. Wenander CERN–2005–009

Speaker: Robert Bark (iThemba LABS)

Presentation_ID625_Bark.pdf

26 The Isotope Harvesting Program at FRIB

The Facility for Rare Isotope Beams (FRIB) recently completed installation of infrastructure needed to collect, purify, and distribute radionuclides that are the otherwise-unused by-products of normal operations. This process is referred to as isotope harvesting, and it takes advantage of rare isotope production and accumulation in FRIB's water-filled primary beam dump. Anticipated harvesting products range from theranositc generators like ⁴⁷Ca/⁴⁷Sc and ⁷⁶Kr/⁷⁶Br to radionuclides needed for fundamental symmetry experiments like ²²⁵Ra and ²²⁹Pa, depending upon the needs of the scientific community and the primary beams being used at FRIB. The capabilities of the new infrastructure will be presented along with updated predictions for radionuclide availability. Commissioning of the isotope harvesting program will commence throughout 2025.

Speaker: Gregory Severin (Michigan State University)

462_Severin.pptx

Parallel Session: 1_Nuclear Astrophysics

Convener: Bao-An Li (Texas A&M University-Commerce)

27 Constraining Neutrino-Mass Hierarchy from Supernova Nucleosynthesis

We propose a new astrophysical method of supernova nucleosynthesis to constrain still unknown neutrino mass hierarchy and discuss the roles of radioactive nuclear reactions. Explosions of single massive stars, i.e. magneto-hydrodynamic-jet supernova (MHD-Jet SN) and collapsar, and binary neutron-star merger are the viable candidate sites for r-process. We will first discuss when and how these astrophysical sites have contributed to the enrichment of the heavy elements in cosmic evolution [1]. We have recently found that the i- and s-processes could occur in the r-process site of collapsar nucleosynthesis [2]. We will present a list of nuclear reactions relevant for these new processes [3]. These explosive phenomena emit extremely large flux of energetic neutrinos that provide unique nucleosynthetic signals of the neutrino-nucleus interactions and flavor conversions at high-density [4,5]. We will, secondly, discuss our recent finding that the collective oscillation and MSW effects at high-density affect strongly the SN nucleosynthesis and the isotopic ratios in SiC X grains could provide a clear signature of constraining still unknown neutrino mass-hierarchy [6].

[1] Y. Yamazaki, Z. He, T. Kajino, et al., Astrophys. J. 933 (2022), 112.
[2] Z. He, T. Kajino, M. Kusakabe, et al., Astrophys. J. Lett. 966 (2024), L37.
[3] Z. He, T. Kajino, Y. Luo, et al., (2025), to be published.
[4] H. Ko, D. Jang, M. Cheoun, et al., Astrophys. J. 937 (2022), 116.
[5] H. Sasaki, Y. Yamazaki, T. Kajino, et al., Phys. Lett. B851 (2024).
[6] X. Yao, T. Kajino, Y. Luo, et al., (2025), to be published

Speaker: Prof. Taka Kajino (Beihang University/NAOJ/University of Tokyo)

Presentation_ID314_Kajino.pptx

28 The Exploration of the Indirect Neutron-Capture Constraints of the 87,89Kr(n,𝜸)88,90Kr reactions in the Astrophysical i-process using the 𝜷-Oslo Method

One of the main questions that is of critical interest in nuclear astrophysics is how elements are produced in stars. The traditional nuclear landscape shows that elements are created through the slow (s), rapid (r) and proton (p) processes. Recently, astronomical observations of Carbon-Enhanced Metal Poor (CEMP) stars have shown ``strange” abundance patterns, which cannot be explained by the s- and the r-processes alone. This observation indicates that an additional nucleosynthesis process is required to explain CEMP abundances, being the astrophysical intermediate (i-) neutron-capture process. The i-process occurs from 2-8 mass units away from the valley of stability. Nuclear properties needed to predict elemental abundances following the i process are relatively well constrained with the exception of neutron-capture reaction rates, which are entirely provided by theory. Recent sensitivity studies have shown that the Rb/Sr abundances are strongly affected as a result of neutron-capture reactions on Kr isotopes. In this talk, the first experimental constraint of the $^{87,89}$Kr(n,$\gamma$)$^{88,90}$Kr reactions will be discussed utilizing the β-Oslo method. This experiment took place using the CARIBU facility at Argonne National Laboratory by exploiting the indirect method of $\beta$-decays from the $^{88,90}$Br nuclei into $^{88,90}$Kr. Subsequent $\gamma$-rays were identified by using the Summing NaI detector, SuN, and the SuNTAN tape transport system. By utilizing the statistical properties of both $^{88,90}$Kr, the $^{87,89}$Kr(n,$\gamma$)$^{88,90}$Kr experimentally constrained cross sections have been extracted and their impact on the astrophysical i-process will be discussed.

Speaker: Sivahami Uthayakumaar (Michigan State University)

Presentation_ID541_Uthayakumaar.pptx

29 Constraining i-process nucleosynthesis with quasi-continuum nuclear data

The gamma-ray decay of nuclear states in the quasi-continuum provides significant constraints on nucleosynthesis processes. In particular, measurements of Nuclear Level Densities (NLDs) and Photon Strength Functions (PSFs) have and will continue to play a central role as these are inputs for the statistical Hauser-Feshbach model. This facilitates the extraction of neutron-capture cross-section data even for nuclei where direct measurements are not feasible. Now, PSF and NLD measurements in previously inaccessible regions of the nuclear chart have become possible due to many facilities worldwide offering enhanced or new state-of-the-art research infrastructure. These range from significant increases in efficiencies for particle and gamma-ray detectors to new or upgraded radioactive ion beam facilities. In parallel, several new experimental and analytical techniques have been developed, enabling more reliable PSF and NLD studies. This collective progress leads to unprecedented insight not only into the structure of nuclei but also to provide experimental constraints relevant to nucleosynthesis processes.
In this presentation, I will provide an overview of the most significant advances made and how these have laid the foundation for novel and ambitious measurements of PSFs and NLDs at radioactive ion beam facilities. Furthermore, I will discuss how our understanding of observed isotopic abundances can be enhanced through the measurement of PSFs and NLDs, using the i-process nucleus 67Ni as an example.

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC02-05CH11231 and supported by the US Nuclear Data Program.

Speaker: Mathis Wiedeking (Lawrence Berkeley National Laboratory)

Presentation_ID260_Wiedeking.pdf

30 First measurement of a weak r-process reaction on a radioactive nucleus.

In this talk, I will present results on the first $(\alpha,n)$ cross-section measurements on beams of $^{86}$Kr and $^{94}$Sr. Both reactions are influential for the weak r-process in neutrino-driven winds of type-II supernovae and neutron star mergers. The measurement of $^{94}$Sr$(\alpha,n)$ constitutes the first weak r-process reaction measured with a radioactive beam. This work was enabled by novel nanostructured Si:He targets, demonstrating their suitability for measurements of astrophysical reactions for the first time. Reactions were identified by recoil-$\gamma$ coincidences using the EMMA mass spectrometer combined with the TIGRESS HPGe array at TRIUMF. The obtained cross-sections are compared with predictions from Hauser-Feshbach theory, from which we also compute a new recommended reaction rate at temperatures characteristic of the weak r-process.

Speaker: Matthew Willians (University of Surrey)

31 Direct measurement of the $^{12}$C+$^{12}$C fusion reaction cross section at stellar energies

The $^{12}$C+$^{12}$C fusion reaction plays a pivotal role in the process of stellar evolution. Despite six decades of studies, there is still a large uncertainty in the reaction rate which limits our understanding of various stellar objects, such as massive stars, type Ia supernovae, and superbursts. In this talk, I will present the preliminary results from the direct measurement of the $^{12}$C+$^{12}$C reaction, obtained by the CARFUSE (CARbon FUsion study at Stellar Energies) collaboration, in the range of E$_{\rm c.m.}$=2.3 MeV to 4.3 MeV using a novel detection system consisting of Time Project Chamber and silicon array and the intense carbon beam provided by the Low Energy high-intensity heavy-ion Accelerator Facility (LEAF) at IMP. The significant discrepancy between our direct measurements and the results derived using the THM approach highlights the need for further improvement in the indirect measurement technique. A new reaction rate is recommended based on our new measurement and the statistical model.

Speaker: Dr Xiaodong Tang (Institute of Modern Physics, CAS)

2025_INPC_tang_v3_web.pdf

Parallel Session: 1_Nuclear Reactions (1)

Convener: Byungsik Hong (Korea University)

32 Pathways to the synthesis of new elements and evaluation of synthesis probabilities

In the experiment, new element synthesis has now succeeded in synthesizing up to element 118 and the periodic table has been named up to Og. Experiments are currently being planned and carried out at experimental facilities around the world with the aim of synthesizing elements 119 and above.
Apart from 48Ca beams, the use of Ti, V and Cr beams is currently being considered. Our group is planning to evaluate the synthesis probability and optimum incident energy for the synthesis of element 119 using these beams, which will be useful for experimental planning.
　The evaluation of the evaporation residual cross section in superheavy element synthesis is generally performed by dividing the whole fusion-fission reaction process into three stages according to the timescale of the reaction. However, in each of these stages, there are several uncertainties and undefined parameters, and it is common practice to adjust these parameters and compare them with experimental values for a highly accurate evaluation.
Based on our analysis, among these parameters, the Coulomb barrier height and the reaction Q-value play a very important role in the evaluation of the evaporation residual cross section. The relationship between these two quantities is particularly important for the formation of new elements after element 119. In this presentation, we employ the Langevin equation as dynamical model and we will discuss the comparison of evaporation residual nucleus cross sections with 48Ca and with Ti, V and Cr beams.

Speaker: Yoshihiro Aritomo (Kindai University)

Presentation_ID54_Aritomo2.pptx

33 Study of fission dynamics using six-dimensional Langevin equation

The dynamical approach to fission using the multi-dimensional Langevin equation has been extensively used as a practical model for calculating the fission observables, such as fission-fragment mass and total kinetic energy (TKE) distributions and their evolution with the excitation energy of compound nucleus.
We investigated for the first time six-dimensional Langevin calculations with the Cassini shape parameterization [1]. The largest dimension achieved in this work allows a more versatile description in fission under the highly flexible deformation space. For example, the appearance of several fission modes in the fission $n\,+\,^{235}$U is demonstrated, and the corresponding scission configuration is derived with high precision. In this presentation, we discuss the results of the fragment mass and TKE distributions and their dependence on the excitation energy of fissioning nuclei.
Fission of neutron-rich fermium region offers a strict benchmark of the model [2]. Our calculation explained a sudden change from mass-asymmetric fission of $^{256}$Fm to symmetric fission of $^{258}$Fm. Recently, the fission of $^{258}\mathrm{Md}$ in excited states was measured at JAEA [3]. While the symmetric fission mode has a comparative yield with asymmetric mode at the excitation energy of $E^*$ = 15.0 MeV, the latter yield increases when extra excitation energy of only 3 MeV was given in $^{258}$Md$^*$. The growth of AS mode with excitation energy, observed for the first time, and strong competition between the modes was explained in the present six-dimensional calculation.

References
[1] V. V. Pashkevich, Nucl. Phys. A 169, 275 (1971).
[2] E.K. Hulet et al., Phys. Rev. C 40, 770 (1989).
[3] K. Nishio et al., submitted to Phys. Rev. C (2024).

Speaker: Kazuki Okada (Japan Atomic Energy Agency)

34 Fission study using multinucleon transfer reactions

We have promoted fission measurement using multinucleon transfer (MNT) reactions. The reaction allows us to study fission of many nuclei, including neutron-rich nuclei, which cannot be populated by other reactions [1]. Also, excitation energy ($E^{*}$) of compound nucleus distributes widely, which can be used to investigate excitation-energy dependence of fission. The experiments were carried out at the JAEA tandem accelerator facility using 18O beam and various radioactive target nuclei ($^{232}$Th, $^{238}$U, $^{237}$Np, $^{243}$Am, $^{248}$Cm) [2,3]. It was demonstrated that data fission-fragment mass distributions (FFMDs) for more than 20 nuclides were obtained in one reaction, and their excitation energy dependence up to $E^{*}$=60 MeV was derived. The measured FFMDs were explained by taking into account the multi-chance fission, i.e. fission after neutron emission [4,5]. From the threshold of the excitation function of fission probably, fission barrier height was derived [6].
Our setup for MNT-induced fission allows us to obtain data for MNT mechanism itself. From the fission-fragment angular distribution relative to the rotational axis of the fissioning nucleus, we determined the average angular momentum for each MNT channel [7]. This measurement is useful for the surrogate reaction study, where effects of different spin distribution of compound nucleus between transfer and neutron-induced reaction needs to be properly taken into account.

Reference
[1] K. Nishio, “Multinucleon-Transfer-Induced Fission”, Handbook of Nuclear Physics, Springer, pp 901-943 (2023).
[2] R. Leguillon et al., Phys. Lett. B 761, 125 (2016).
[3] M.J. Vermeulen et al., Phys. Rev. C 102, 054610 (2020).
[4] K. Hirose et al., Phys. Rev. Lett. 119, 222501 (2017).
[5] S. Tanaka et al., Phys. Rev. C 100, 064605 (2019).
[6] K.R. Kean et al., 100, 014611 (2019).
[7] S. Tanaka et al., Phys. Rev. C 105, L021602 (2022).

Keywords : Fission, Multinucleon transfer reaction, Multichance fission

Speaker: Katsuhisa Nishio (Japan Atomic Energy Agency)

Presentation_ID68_Nishio (2).pdf

35 Study of neutron induced fission of 235U and 237Np with FALSTAFF spectrometer at NFS

The study of nuclear fission continues to attract significant interest due to its fundamental scientific importance and its practical applications in nuclear reactor technology. The FALSTAFF project aims to deliver high-quality experimental data to enhance our understanding of the fission process, particularly in the context of improving predictive capabilities of fission models. These models are critical for nuclear data evaluations essential for next-generation reactor designs.

Recent experiments using the FALSTAFF spectrometer[1] were performed at the Neutron For Science (NFS) facility of GANIL/SPIRAL2 [2] to study neutron-induced fission of $^{235}$U and $^{237}$Np. Using the one-arm configuration of FALSTAFF, these experiments covered an incident neutron energy range from 0.5 to 40 MeV, enabling the measurement of Fission Fragment Mass Distributions (FFMDs) and fragment kinetic energies. Fragment velocities were determined using the time-of-flight method with a pair of Secondary Electron Detectors (SEDs)[3], comprising a thin emissive foil and a Multi-Wire Proportional Counter (MWPC). Such measurements are crucial for understanding the damping of nuclear shell effects as a function of the incident neutron beam energy i.e., the excitation energy of the fissioning system.

In this presentation, we will share the results obtained for $^{235}$U, focusing on the FFMDs and the evolution of fragment kinetic energies with neutron energy. Additionally, preliminary results from the $^{237}$Np experiment, conducted in October 2024, will also be presented. These measurements, spanning an extensive neutron energy range, represent a significant contribution to the experimental understanding of fission in the MeV domain, where data are scarce. The presentation will conclude with recent updates on the ongoing construction and commissioning of our second arm of FALSTAFF, for the detection of both fission fragments in coincidence.

References
[1] D. Doré et al., Nucl. Data. Sheets. 119, 346-348 (2014).
[2] X. Ledoux et al., Eur. Phys. J. 57, 257 (2021).
[3] J. Pancin et al., J. Instrum. 4, P12012 (2009).

Speaker: Deby Treasa Kattikat Melcom (GANIL, France)

Presentation_ID108_Kattikat_Melcom.pdf

36 Reaction mechanism of evaporation residue for multi-nucleon transfer reaction with heavy nuclei

There is a limit to the production of neutron-rich nuclei by traditional fusion reactions. Therefore, in recent years, multi-nucleon transfer (MNT) reactions have attracted attention as a method of producing neutron-rich nuclei [1]. However, the reaction mechanism is not yet well understood due to its novelty and complexity. In the future, it will be necessary to estimate the physical quantity of evaporation residue (ER) in the production of neutron-rich nuclei of heavy and superheavy nuclei. In this study, we construct a dynamical model that describes the dynamics of the MNT reaction and verify the model by comparing it with experimental data to clarify the reaction mechanism.

This study aims of deal with the production of neutron-rich nuclei in heavy and superheavy elemental regions. As a first step, to clarify the reaction mechanism, we studied the angular momentum of the ER produced by MNT reaction and the emission angle of projectile-like nuclei. In the region of heavy and superheavy nuclei, it is known that the fission process of ERs depends on their angular momentum, and the information of angular momentum is important to know the survival probability of the ER [2]. The emission angles of projectile-like nuclei are also experimentally observable data, which is necessary information for angular momentum prediction. There is a correlation between angular momentum and the emission angle of projectile-like nuclei.

The theoretical model we use is based on the two-center shell model to describe the configuration of nuclei [3]. The time evolution of the configuration is described by the multidimensional Langevin equation [4]. In this presentation, we show the dynamics of the MNT reaction using parameters fitted with preliminary experimental data. And we will discuss the factors we need to know about in future reactions between heavy nuclei. The effect of the angular momentum of ERs on the following fission process is also discussed.

References
[1] V. Zagrebaev, et al., Phys Rev C 73, (2006) 031602.
[2] S. Tanaka, et al., Phys. Rev. C 105, (2022) L021602.
[3] J. Maruhn and W. Greiner, Z. Phys 251, (1972) 431.
[4] V. Zagrebaev and W. Greiner, J. Phys. G 34, (2007) 2265-2277.

Speaker: Kohta Nakajima (Kindai Univ.)

Presentation_ID50_Nakajima.pptx

37 Important role of relationship between reaction Q-value and Coulomb barrier height in synthesizing new superheavy elements

In recent years, the synthesis of new superheavy element (SHE) has been paid attention around the world. When synthesizing SHEs, hot fusion using 48Ca as projectile and actinides as targets is successful for many SHEs up to Og (Z=118) [1,2]. In synthesizing SHEs after Z=119 by hot fusion, if 48Ca is used as projectile, it is necessary to use nuclides after Es (Z=99) as targets. However, nuclides after Es (Z=99) have so short half-lives, it is not practical to use them as targets. Therefore, to synthesize SHEs after Z=119, it is necessary to use projectile with a higher number of protons than 48Ca. This allows the target to be determined relatively stable nuclide in actinides.

The synthesizing of SHEs includes touching process, formation process, and decay process. We calculate evaporation residue cross section by combining three probabilities of these processes. The touching probability is calculated by coupled-channel method [3,4]. The formation probability of compound nucleus is calculated by dynamical model with Langevin equation [3]. And the survival probability of excited compound nucleus is calculated by statistical model [5]. In this study, we calculated the evaporation residue cross sections using 48Ca and 50Ti, 51V and 54Cr, which have more protons than 48Ca, as projectiles and actinides as targets. And we analyzed the effect of difference in combination of projectiles and targets on cross sections.

We mainly discuss the effects of reaction Q-value and Coulomb barrier height in the evaporation residue cross sections. We use Q-value that depends on the mass tables. And we use Bass model to estimate the Coulomb barrier height. The values of these parameters differ depending on the combinations of nuclei, and these parameters play very important roles in the estimation of the excitation functions of cross sections. In this presentation, better combinations of projectiles and targets in the synthesis of new superheavy elements will be discussed.

References
[1] Yu. Ts. Oganessian, et al., Phys. Rev. C 70, 064609 (2004).
[2] Yu. Ts. Oganessian, et al., Phys. Rev. C 74, 044602 (2006).
[3] Y. Aritomo, et al., Phys. Rev. C 85, 044614 (2012).
[4] K. Hagino, et al., Computer Physics Communications 123 (1999) 143-152.
[5] Y. Aritomo, et al., Phys. Rev. C 59, 769, February 1999.

Speaker: Kosuke Kawai (Kindai Univ.)

Presentation_ID51_Kawai.pptx

38 Understanding the fission dynamics in $^{12}$C+$^{193}$Ir system

Since the discovery of fission, heavy-ion induced reactions leading to fission of actinides have been extensively investigated both experimentally and theoretically. The experimental data in the pre-actinide region is limited due to very low fission probability leading to less statistics at low energies where the shell effects are more prominent. However, the unexpected onset of fission-like events at slightly above barrier energies needs to be investigated for better insight into the low-energy heavy-ion induced fission. An experiment has been performed in $^{12}$C+$^{193}$Ir system at E$_{\rm lab}$ = 83.99, 80.99, 74.81 and 70.08 MeV using the 15UD Pelletron accelerator facilities at the Inter-University Accelerator Center, New Delhi. Prime objective of this study is to investigate various aspects of heavy-ion induced fission resulting from the evolution of a composite system via complete and/or incomplete fusion in the $^{12}$C + $^{193}$Ir system.

The production cross-sections of fission-like events were measured to draw mass distribution and analysed to obtain the dispersion parameters of fission fragments. In this work, a large number of fission-like events in the mass range 72$\leq$A$\leq$134 were identified at four studied energies. The resulting mass distribution of the fission-like residues was symmetric and fitted with a Gaussian function, peaking around the half mass of the compound nucleus, indicating their onset from the decay of the compound nucleus formed via complete and/or incomplete fusion [1]. Further, the mass variance ($\sigma_m^{2}$) of fission-like events increases with excitation energy above the Coulomb barrier, suggesting a broader distribution of fission fragment masses at higher energies. This trend in mass variance with excitation energy aligns with previous findings by Ghosh et al.[2], at energies above the Coulomb barrier. To gain further insights into the nature of mass distribution, the measured widths are compared with the statistical model calculations performed for fusion-fission channels. The role of the entrance-channel mass-asymmetry ($\alpha$ = (A$_{\rm T}$-A$_{\rm P}$)/(A$_{\rm T}$+A$_{\rm P}$)) on the mass distribution of fission-like fragments, and the effect of $\alpha$ on the mass variance ($\sigma_m^{2}$) has been studied. The results indicate that there is a linear increase in $\sigma_m^{2}$ with increasing mass $\alpha$ of the entrance channel. This suggests a broader mass distribution of fission-like residues for more mass-asymmetric systems. Detailed results and analysis will be presented during the conference.

[1] Rupinderjeet Kaur et. al, under review (2025); arXiv:2409.14520.

[2] T. K. Ghosh, S. Pal, K. S. Golda, and P.Bhattacharya, Phys. Lett. B 627, 26 (2005), and the references therein.

Speaker: Rupinderjeet Kaur (IIT Ropar)

Presentation_ID612_Kaur.pdf

Parallel Session: 1_Nuclear Reactions (2)

Convener: Deuk Soon AHN (Center for Exotic Nuclear Studies, IBS)

39 Fission studies using complete measurements in inverse kinematics

Fission reactions induced by relativistic heavy nuclei in combination with a large
acceptance dipole magnet and advance tracking and time-of-flight detectors
(SOFIA detection setup at GSI) allowed for the first time the complete
identification of both fission fragments in atomic and mass number [1]. By using
different target materials, it was also possible to favour fission reactions at low
and high excitation energies, namely lead inducing coulex and protons inducing
spallation. In addition, these kinematic conditions also allow the study of a wide
variety of unstable fissile nuclei. The first experiments made it possible to study
the role of shell effects in fission [2] and the dynamics of fission at high
excitation energies [3].
More recently, these experiments have been enhanced by merging the SOFIA
and R3B/FAIR setups. The R3B target area detectors (silicon tracker and Califa
calorimeter) allow the determination of the missing energy in quasi-free
scattering (p,2p) reactions using a liquid hydrogen target. In the case of (p,2p)-
induced fission reactions, the missing energy corresponds to the excitation
energy of the fissioning nuclei, which was not accessible in previous
measurements. In addition, the new setup is able to measure the gamma rays
and neutrons emitted during the fission process. These will be the first complete
kinematic measurements of fission reactions.
In this talk I will present the first results of the study of the fission process with
the R3B setup at GSI/FAIR. In particular, I will show how the complete
identification of both fission fragments and the measurement of the excitation
energy of the fissioning nucleus allowed us to systematically study the shell
effects from the simultaneous measurement of the mass and charge fission
yields, but also the evolution of the shell effects on the fission yields with
temperature and the sharing of the excitation energy between the two fission
fragments.

[1] E. Pellereau et al., Phys. Rev. C 95, 054603 (2017).
[2] A. Chatillon e t a l . , Phys. Rev. Lett. 124, 202502 (2020).
[3] J.L. Rodríguez-Sánchez e t a l ., Phys. Rev. C 94, 061601(R) (2016).

Speaker: Jose Benlliure (Instituto de Física Corpuscular (CSIC - Universitat de València))

INPC25_Benlliure_fission.pptx

Presentation_ID507_Benlliure.pptx

40 Fission processes in heavy and superheavy elements within the dinuclear system model

Within the dinuclear system model (DNS) approach the model was built to describe and predict half-live times of $\alpha$-decay and spontaneous fission. DNS model is based on collective coordinates of the distance $R$ between the centers of mass of the clusters and charge asymmetry $\eta_Z = {Z_H-Z_L\over Z_H+Z_L}$, where $Z_{H, L}$ are charge numbers of heavy and light cluster, respectively. This approach allows to achieve a good agreement with the available experimental data either for $\alpha$-decay or spontaneous fission with the same set of parameters for all nuclei considered.

With the proposed model the isotopic dependence peculiarities for even-even nuclei are successfully described. The change in the isotopic behaviour around $N=152$ neutron shell between No and Rf and heavier nuclei are described with the driving potential and inertia parameters.

For even-odd nuclei the hindrance factor of spontaneous fission is related to the spin dependence of the formation probabilities of the binary cluster configurations which are
attributed to the spontaneous fission.

Also the model is applied to the description of the decay of isomeric states. It's shown that the half-lives change in transition from the ground state to isomeric state is determined by interplay of spin difference between ground and isomeric state and the isomer energy. This influence in the model is described with the changes these values are making for the driving potential. An ability to describe ground and isomeric states decay allows us to correctly describe $\alpha$-decay chains for produced superheavy nuclei, which was used for the description of the decay schemes for newly produced $^{273,\ 275}$Ds.

Speaker: Ivan Rogov (Joint Institute for Nuclear Research)

Rogov_INPC_2025.pdf

41 Dynamical analysis of fission reactions for RI beam production at RAON using the Langevin Method

RAON, the Korean heavy-ion accelerator, integrates isotope separation on-line (ISOL) and in-flight fragmentation (IF) technologies to explore a novel approach for rare isotope (RI) production. Among these, the ISOL method employs light particle beams, such as protons, neutrons, and deuterons, to induce fission reactions in various target nuclei, including uranium-238, enabling high-yield isotope production at low energy. In this study, we analyze fission reactions initiated by proton beams with energies ranging from 20 to 80 MeV. The primary focus is on uranium-238, which serves as the main target for RI beam generation at RAON. To achieve this, we employ a dynamical model based on the fluctuation-dissipation theorem, which utilizes the Langevin equation to describe stochastic motion. The two-center shell model (TCSM) defines macroscopic reaction coordinates that explain the evolution of nuclear shapes, enabling simulations of fission fragment mass distributions. In addition, we incorporate additional potential landscapes along the isobar line, referencing nuclear stability valleys in the nuclide chart. This approach enables the model to calculate independent fission yields for specific proton numbers (Z) with precision using a 3+1 Langevin equation framework. This dynamical analysis not only reproduces existing experimental data with high accuracy but also provides predictive insights into rare isotope production. Furthermore, this framework can be extended to other actinides and various target nuclei combinations, enabling applications in rare isotope generation and nuclear research at RAON.

Speaker: Chang-hoon Song (PNU)

Presentation_ID492_Song(1).pptx

Presentation_ID492_Song(2).pptx

42 Fusion-fission dynamics at higher excitation energies with 16O projectile

Fast fission, quasifission, and pre-equilibrium fission are examples of non-equilibrium phenomena that impede the synthesis of super heavy metals by heavy-ion-induced reactions [1].
Understanding the kinetics of these processes requires accurate measurements of mass-energy distributions across a broad range of excitation intensities and compound nuclei.
The growing complexity with increasing excitation energies is a major obstacle to achieving regular measurements of pure fission fragment mass distributions at high energies. Numerous reaction channels, such as compound nuclear fission, quasi-elastics, deep inelastic reactions, fast fission, and quasi-fission events, are the source of this complexity [2]. In intermediate or high-energy nuclear processes, it gets increasingly harder to distinguish fission events from other reaction products.

To gain a deeper understanding of the kinetics of fusion-fission events at relatively high excitation energies, we present measurements from various reactions involving a 16O projectile, with energies generally ranging between 7 and 10 MeV/A. Our research has revealed the occurrence of fast fission events characterized by a mass imbalance of approximately 0.22 [3], particularly at higher excitation energies. These findings suggest the presence of rapid fission processes under these conditions.
Experiments with heavier beams and at higher energies are expected to provide critical insights into the systematic nature of these fast fission processes. Such investigations will help to understand the underlying mechanisms and characteristics of fission dynamics at elevated excitation energies. The recently operational K500 Superconducting Cyclotron facility is currently hosting a series of experiments aimed at further exploring these phenomena, offering a unique opportunity to enhance our understanding of fusion-fission dynamics and refine existing theoretical models

Reference:

1] D. Hinde et. al., Progress in Particle and Nuclear Physics 118, 103856, (2021).
[2] E. Vardaci et. al., Phys. Rev. C 101, 064612 (2020).
[3] K. Atreya et. al., Phys. Rev. C 109, 064620 (2024).

Speaker: Kirti Atreya (VECC,Kolkata)

43 Analysis of dynamics around contact regions in fusion reactions

At present, using the fusion reaction between the projectile and target nuclei, up to Og has been successfully synthesized and projects to synthesis of new superheavy elements (SHEs) are underway at several facilities around the world. However, the synthesis probability of SHEs is extremely low, and most of them undergo quasi-fission, which cannot sustain a compound nucleus after contact. Therefore, this study aims to elucidate the complex dynamics of quasi-fission by systematically investigating the reaction mechanism.
　To understand the dynamics of the fusion process, we focused on the correlation between fragment mass and its emitting angle of quasi-fission [1]. Our group has succeeded in reproducing the mass angular distribution (MAD) of the emitted nuclei by using a dynamical model, considering the deformation of the target nuclei [2]. The dynamical model is based on the liquid drop model and the shell effect to determine the shape of the nucleus and its potential at that time, and the time evolution of the shape from fusion to fission can be traced by solving the langevin equation. Calculations of fusion reactions require fitting of indefinite parameters from experimental data, such as energy dissipation due to friction between nuclei and the transition from diabatic to adiabatic potentials, which are suitable for equilibration of the system.
　In this study, we calculated the 42 systems experimented in Ref. [1] under identical conditions except for the number of nucleons and summarized the MAD. Among these, we correct the uncertain parameters and systematically evaluate 64Ni+170Er, 48Ti+186W, and 32S+202Hg, which form the compound nucleus of 234Cm.
References
[1] R. du Rietz et al., “Mapping quasifission characteristics and timescale in heavy element formation reactions”, Phys. Rev. C 88, 054618 (2013)
[2] Shota Amano et al., “Effects of neck and nuclear orientations on the mass drift in heavy ion collisions”, Phys. Rev. C 109, 034603 (2024)

Speaker: Masaki Ueno (Kindai Univ.)

Presentation_ID488_Ueno.pptx

44 Fusion of 12C + 28Si at deep sub-barrier energies

Heavy-ion fusion reactions are essential to investigate the fundamental problem of quantum tunnelling of many-body systems in the presence of intrinsic degrees of freedom.
The fusion of light nuclei is a base for the understanding of the astrophysics reaction networks responsible for energy production and elemental synthesis in stellar environments [1]. Fusion enhancements are found near the Coulomb barrier, however, the hindrance phenomenon shows up [2] at lower energies. Fusion of light systems has Q>0, and identifying hindrance requires challenging measurements, so studying slightly heavier cases allows a reliable extrapolation towards the lighter ones. Here, we present the results of recent fusion cross-section measurements for 12C + 28Si, performed at the INFN-Laboratori Nazionali di Legnaro, with the 28Si beams from the XTU Tandem accelerator. We have used the combined set-up of the gamma-array AGATA [3], and two 4” annular DSSD Si detectors to identify and count the fusion evaporation events by coincidences between the prompt gamma-rays and the light-charged particles (p, alpha) evaporated from the compound nucleus. We have used the particle identification method (PID) to distinguish proton and alpha evaporation channels.
Five energies have been measured from 50 to 29.5 MeV. These energy points complete and extend the excitation function previously obtained with the electrostatic deflector setup, which fixes the absolute cross-section scale.
The AGATA-particle coincidence method has allowed us to measure the fusion yields down to sigma~100 nb. The comparison to coupled-channel calculations indicates that the sub-barrier fusion cross-section enhancement is limited, and the hindrance phenomenon shows up at the lowest energies where the cross-sections approach the no-coupling limit. We note that the behaviour of the present system is quite similar to the one of the nearby case 12C+30Si [4] measured some years ago, despite the different structure of the two silicon isotopes.
The final experimental results will be presented together with a systematic of several medium-light cases, paving the way to a better understanding of the slightly lighter astrophysical systems.

[1] C.L. Jiang et al., Eur. Phys. J. A57, 235 (2021)
[2] C.L. Jiang et al., Phys. Rev. Lett. 89, 052701 (2002)
[3] J.J. Valiente-Dobón et al., Nuc. Instr. Meth. A1049, 168040 (2023)
[4] G. Montagnoli et al., Phys. Rev. C 97, 024610 (2018)

Speaker: Giuseppe Andreetta (INFN-LNL and UNIPD)

Presentation_ID538_Andreetta.pdf

Parallel Session: 1_Nuclear Structure (1)

Convener: Bing Guo (China Institute of Atomic Energy)

45 Photo-Nuclear Reaction of Light Nuclear Studied by Proton Scattering

The study of photo-nuclear reactions is crucial for understanding nuclear structure and astrophysical processes. The PANDORA (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astrophysics) project aims to systematically investigate these reactions in nuclei with mass numbers below 60. We will use virtual photon exchange through proton scattering and high-intensity real-photon beams from laser Compton scattering to excite target nuclei. The subsequent decay particles and gamma-rays will be detected to measure photo-absorption cross-sections and decay branching ratios, covering the giant dipole resonance.
Several nuclear models, including anti-symmetrized molecular dynamics, mean-field type models, large-scale shell model, and ab initio models, will be employed to predict the systematic behavior of photo-nuclear reactions. The primary objective of the PANDORA project is to elucidate the energy loss mechanisms of ultra-high-energy cosmic ray (UHECR) nuclei during intergalactic propagation.
UHECRs, observed on Earth up to energies above 10^20 eV by large cosmic-ray air-shower observatories such as Pierre Auger and Telescope Array, remain a mystery in terms of origin, acceleration mechanisms, and composition. Recent analyses suggest a heavier mass composition for UHECRs at the highest energies. UHECR nuclei are predicted to lose energy primarily by emitting particles following photo-nuclear excitation by cosmic microwave background photons. Thus, understanding photonuclear reaction cross-sections and decay branching ratios is essential for interpreting the energy and mass evolution of UHECRs.
I will introduce the experimental method for studying the electric dipole excitation of nuclei and photo-nuclear reactions by proton scattering at the Research Center for Nuclear Physics, Osaka University, and report on the status of the experimental results at RCNP.

Speaker: Atsushi Tamii (Research Center for Nuclear Physics, Osaka University)

Presentation_ID558_Tamii.pdf

46 Probing alpha clusters in the ground state of 12C via alpha-knockout reactions

Alpha clusters in light nuclei are known to play a significant role in nucleosynthesis. Among them, the Hoyle state with a three-alpha cluster structure is crucial for the synthesis of $^{12}\mathrm{C}$ via the triple-alpha-fusion reaction. An ab initio no-core Monte Carlo Shell Model calculations predicted that alpha clusters present not only in the Hoyle state, but also in the ground state of $^{12}\mathrm{C}$ [1]. It is thus interesting to experimentally measure the alpha cluster component in the ground state of $^{12}\mathrm{C}$ and compare it with the ab initio and cluster model predictions. It could help to understand the coexistence and competition of the cluster and shell-model-like components in nuclei. Recent studies show that the alpha knockout reaction is a promising tool for probing the strength of alpha clusters in the ground state [2].
At the RCNP Cyclotron Facility, we conducted measurements of the alpha knockout reaction $^{12}\mathrm{C}$(p,pα). A 400 MeV proton beam was accelerated and irradiated onto a natural carbon target. By measuring the proton and alpha particles in coincidence using a double-arm spectrometer, we successfully obtained the alpha separation energy spectrum of $^{12}\mathrm{C}$. From the reaction yield, the differential cross-section will be determined, enabling us to extract the strength of alpha clusters in the ground state of $^{12}\mathrm{C}$.
In this presentation, we will provide a detailed introduction of the experiment and discuss the results.

[1] T. Otsuka, T. Abe et. al, Nat Commun 13, 2234 (2022).
[2] J. Tanaka, Z.H. Yang et. al, Science 371, 260-264 (2021).

Speaker: Fengyi Chen (Osaka University)

Presentation_ID114_Chen.pptx

47 The observation of a candidate for BEC-like state in 14C

In the framework of Tohsaki-Horiuchi-Schuck-Röpke (THSR) wave function approach, the 0$^+_2$ state at 7.65MeV in $^{12}$C (Hoyle state) is recognized as featuring the Bose-Einstein Condensation (BEC)state [1]. When one α-particles in $^{12}$C is replaced with $^{6}$He, a system of three bosons can also be formed. And if all clusters are moving in relative s-wave, it represents a possible Hoyle-like configuration for $^{14}$C[2].
Based on the above-mentioned anticipation, we conducted an experiment using $^{14}$C as the projectile which was excited to very high lying states followed by three-cluster decay. This experiment was carried out at the Radioactive Ion Beam Line at the Heavy Ion Research Facility in Lanzhou (HIRFL-RIBLL1). Special efforts were devoted to coincidently measure and identify three helium clusters at forward angles.
A prominent resonance above the $^6$He + 2$\alpha$ threshold were firmly identified after selecting the $^8$Be(g.s.) + $^6$He decay channel. Analysis of angular correlation and decay suggests a spin-parity assignment of $J^\pi = 0^+$. Our finding is further supported by the microscopic 3α+2n GCM model and Control neural network calculations, which provides a valuable insight into the structural and dynamic behavior of unstable nuclei.

[1]. FREER M, FYNBO H. Progress in Particle and Nuclear Physics, 2014, 78: 1. DOI: 10.1016/j.ppnp.2014.06.001.https://doi.org/10.1007/s41365-024-01588-x
[2]K. Wei, Y. Ye and Z. Yang, "Clustering in nuclei: progress and perspectives", Nucl. Sci. Tech. 35, 216(2024), https://doi.org/10.1007/s41365-024-01588-x

Speaker: Kang Wei (School of Physics, Peking University)

Presentation_ID218_Wei.pdf

48 Investigation of the σ-bond linear-chain molecular structure in 14C

A recent inelastic-excitation and cluster-decay experiment, $^2$H($^{14}$C, $^{14}$C$^*$->$^{10}$Be+$^4$He)$^2$H, was conducted at an incident beam energy of 27.5 MeV/A. Neutron-rich 14C projectile were inelastically excited to high-lying states beyond 20 MeV, which cover the theoretically predicted linear chain molecular rotational band with the $\sigma$-bond configuration. All three final particles in this reaction were detected, allowing the selection of the decay paths from the $^{14}$C-resonances to various states of $^{10}$Be fragment, based on the Q value spectrum. And the detection in most forward angle raises the chance for observing the near-threshold states with small relative energies. The 22.2 MeV state of $^{14}$C primarily decays to a state near 6 MeV in its daughter nucleus $^{10}$Be, consistent with previous experimental observations and theoretical predictions. This state is very likely the predicted band head of the $\sigma$-bond linear-chain molecular states of $^{14}$C. Further spin-parity analysis is still on the way which may provide stronger evidence.

Speaker: Weiliang Pu (Peking University)

Presentation_ID442_Pu.pptx

49 Alpha particles as building block of $^{16}\mathrm{O}$ ground state probed by alpha knockout reaction

Can alpha particles be the basic building blocks of atomic nuclei? The conventional mean-field picture with nucleons as basic degrees of freedom is considered to dominate, particularly in the ground state of the doubly magic nucleus $^{16}\mathrm{O}$. On the other hand, alpha cluster theories have predicted their existence in the ground state of $^{16}\mathrm{O}$ [1, 2, 3]. Recently, proton-induced alpha-knockout reactions have been established as an effective probe for studying alpha clusters in the nuclei [4]. The reaction cross section of $^{16}\mathrm{O}(\mathrm{p,p\alpha})$ is a good measure for the number of alpha clusters.
We performed an experiment at RCNP using a 400 MeV proton beam incident on an oxygen-containing target. A double-arm spectrometer analyzed the energies and momenta of recoil protons and alpha particles emitted by the $^{16}\mathrm{O}(\mathrm{p,p\alpha})^{12}\mathrm{C}$ reaction.
The alpha separation energy spectrum (Fig.1) and its yield provides direct evidence of an alpha clusters in the ground state of $^{16}\mathrm{O}$. Furthermore, three distinct peaks revealed in the spectrum, corresponding to different motions of the alpha clusters in atomic nuclei. The momentum distribution of alpha clusters in $^{16}\mathrm{O}$, which analysis is ongoing, will clarify their motion.
In this presentation, we will discuss the experimental results of the $^{16}\mathrm{O}(\mathrm{p,p\alpha})^{12}\mathrm{C}$ reaction and their interpretation.

[1] D.M. Brink et. al, $\it{Phys.Lett.B.}\ \textbf{33}$, 143-146 (1970)
[2] R. Bujker and F. Iachello, $\it{Phys.Rev.Lett.}\ \textbf{112}$, 152501 (2014).
[3] E. Epelbaum et. al, $\it{Phys.Rev.Lett.}\ \textbf{112}$, 102501 (2014).
[4] J. Tanaka, Z.H. Yang et. al, $\it{Science}\ \textbf{371}$, 260-264 (2021).

Speaker: Taichi Miyagawa (Research Center for Nuclear Physics, Osaka U)

Presentation_ID113_Miyagawa.pptx

50 Experimental Study on Negative-parity Linear-chain Rotational Bands in 16C

There are indications of the existence of negative-parity linear-chain configurations in neutron-rich 16C nuclei , which is worthy of further study [1,2]. Theoretical studies propose the existence of a Π-σ-bond negative-parity linear-chain rotational band in 16C, which is more isolated from other non-clustering states. Further experiments are needed for its identification.
Based on these predictions, we have conducted an experiment in 2022 at the Radioactive Ion Beam Line at the Heavy Ion Research Facility in Lanzhou (HIRFL-RIBLL1) using secondary beams of 16C impinging on a (CD2)n target. Inelastic excitation induced by the deuterium target and the following up cluster-decay were measured.
In this presentation, we will present the current progress of the data analysis and the preliminary results so far obtained, in order to have discussions and anticipation about these particular chain structure in neutron-rich carbon isotopes.

[1] T. Baba et al. PHYSICAL REVIEW C 94 (2016) 044303.
[2] T. Baba et al. PHYSICAL REVIEW C 97 (2018) 054315.

Speaker: Ying Chen (Peking University)

Presentation_ID194_Chen.pdf

Parallel Session: 1_Nuclear Structure (2)

Convener: Sonia Bacca (Johannes Gutenberg-Universität Mainz)

51 Nuclear structure and dynamics in relativistic density functional theory

The relativistic density functional theory (DFT) , implemented with self-consistency and taking into account various correlations by spontaneously broken symmetries, provides an excellent platform for the nuclear structure and dynamics. In this talk, the ideas and general formalism of the relativistic DFT will be introduced, together with new developed approaches and applications as well as future perspectives. Topics covered include the global nuclear mass table with continuum and deformation effects, the RElativistic Configuration-interaction Density functional theory (RECD) for novel nuclear rotations and neutrinoless double beta decay, the shell-model-like approach based on the relativistic DFT to treat exactly the pairing correlations, the time-dependent relativistic DFT for shape fluctuations in chiral rotation, the entanglement and cross-section in multinucleon transfer reaction, and quantum fluctuations and dissipative mechanism in nuclear fission.

Speaker: Prof. Pengwei Zhao (Peking University)

Presentation_517_Zhao.pdf

52 Exotic nuclear properties in deformed relativistic Hartree–Bogoliubov theory in continuum

The deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) has proven to be a powerful framework for investigating exotic nuclear phenomena, particularly in nuclei near the drip-lines. By self-consistently incorporating nuclear deformation, pairing correlations, and continuum effects, the DRHBc theory has significantly advanced our understanding of nuclear structure and stability.
This presentation focuses on two key phenomena explored using the DRHBc theory: shape coexistence and drip-line predictions. Specifically, it examines the critical role of deformation in predicting the neutron drip-line, followed by the identification of candidate nuclei for shape coexistence in the O-Ca region using the DRHBc theory. These predictions show excellent agreement with experimental data and are expected to be further validated by new rare isotope beam facilities such as RAON, FRIB, and others.

Speaker: Myeong-Hwan Mun (Kyungpook National University)

Presentation_ID568_Mun.pptx

53 Exact-exchange relativistic density functional theory for atomic nuclei

The inclusion of nucleonic exchange energy has been a long-standing challenge for the relativistic density functional theory in nuclear physics. We propose an orbital-dependent relativistic Kohn-Sham density functional theory to incorporate the exchange energy with local Lorentz scalar and vector potentials, which are solved efficiently using the relativistic optimized effective potential method. The new theoretical framework is also extended to the three-dimensional coordinate space for the first time. The obtained binding energies and charge radii for spherical and axially deformed nuclei are benchmarked with the results given by the traditional relativistic Hartree-Fock approach, which involves intractable nonlocal potentials. It demonstrates that the present framework is not only accurate but also efficient. The triaxial neutron-rich 104-120Ru isotopes are investigated with the exchange correlations, which is beyond the current capacity of the traditional relativistic Hartree-Fock approach. The results notably indicate the 𝛾-softness of these neutron-rich nuclei, which is consistent with experimental observations. This novel approach establishes a foundation for the study of nuclei without imposing any symmetry restrictions employing relativistic density functional with exchange correlations.

Speaker: Dr Qiang ZHAO (China Institute of Atomic Energy)

Presentation_ID654_ZHAO.pdf

54 Impact of the meson-exchange currents on the magnetic dipole moments in odd near doubly magic nuclei analyzed within nuclear DFT framework

The study of nuclear electromagnetic moments plays a crucial role in understanding the structure of atomic nuclei [1]. While the electric quadrupole moments in atomic nuclei indicate nuclear deformation and collectivity, the magnetic dipole moments are sensitive to the single-particle properties of valence nucleons. In our nuclear DFT methodology, the intrinsic electric quadrupole and magnetic dipole moments in odd nuclei are generated by the self-consistent shape and spin core polarization effects induced by the unpaired nucleon. The spectroscopic moments of angular-momentum-projected wave functions are determined and compared with the available experimental data without introducing effective charges and $g$-factors. We have applied our methodology to calculate the spectroscopic moments in heavy deformed open-shell odd nuclei in several regions of the nuclear chart [2, 3, 4].

In contrast to the predicted quadrupole moments that generally reproduce the data very well, the calculated magnetic dipole moments may deviate from the data sometimes by a significant amount. To improve the agreement with the data, following Refs. [5, 6], we extended the one-body magnetic dipole moment operator used in the nuclear DFT by two-body terms derived from the meson-exchange currents. We have incorporated these terms into our recent calculations for the odd-nuclei around eight doubly magic nuclei ($^{16}$O, $^{40}$Ca, $^{48}$Ca, $^{56}$Ni, $^{78}$Ni, $^{100}$Sn, $^{132}$Sn, and $^{208}$Pb). In this talk, the impact of the inclusion of the meson-exchange currents on the spectroscopic magnetic dipole moments will be discussed.

Keywords: nuclear DFT, magnetic moments, meson-exchange currents

[1] G. Neyens, Rep. Prog. Phys. 66, 633 (2003)
[2] P. L. Sassarini et al., J. Phys. G: Nucl. Part. Phys. 49, 11LT01 (2022)
[3] J. Bonnard et al., Phys. Lett. B 843 138014 (2023)
[4] H. Wibowo et al., to be published
[5] R. Seutin et al., Phys. Rev. C 108, 054005 (2023)
[6] T. Miyagi et al., Phys. Rev. Lett. 132, 232503 (2024)

Speaker: Herlik Wibowo (School of Physics, Engineering and Technology, University of York, UK)

Presentation_ID235_Wibowo.pdf

55 Functional Renormalization Group Method for Finite Nuclei

The functional renormalization group (FRG) is a powerful tool for investigating effects beyond the mean-field approximation. In this presentation, we apply the FRG method to finite nuclei and discuss our findings for finite nuclei. Specifically, we implement FRG results into relativistic continuum Hartree-Bogoliubov theory, which treats both pairing and continuum effects in a self-consistent manner. As a first step, we examine symmetric nuclei and analyze how fluctuations influence key nuclear properties, such as binding energies and charge radii. Additionally, we explore the role of partial chiral symmetry restoration in finite nuclei, as our model Lagrangian respects both chiral symmetry and its spontaneous breaking.

Speaker: Youngman Kim (CENS, IBS)

FRG-INPC2025-YK.pptx

Parallel Session: 1_Nuclear Structure (3)

Convener: Rodney Orford (Lawrence Berkeley National Laboratory)

56 A novel shell model for highly excited states in heavy, deformed nuclei

There is growing demand for better understanding of highly excited nuclear states. For nuclear astrophysics and practical applications, such as reactor technology and transmutation of nuclear waste, radiative neutron capture commonly described by the Hauser-Feshbach theory requires nuclear level density (NLD) and gamma-ray strength function (gSF) as model inputs. Calculation of effective weak-process rates of beta decay and electron capture under stellar conditions involves necessarily nuclear excited states. In nuclear fission study, each primary fission fragment is treated as a compound nucleus, for which knowledge of the initial spin-distribution (SD) of excited states is crucial. All these (NLD, gSF, weak rates, SD) are structure quantities, however, exhibit strong statistical features with high excitations.

In contrast to tremendous success achieved in the theoretical study for low-excitation regions where individual levels are discussed in detail, less has been studied for highly excited states. We show that, with new breakthroughs in many-body calculations, shell-model calculations for highly excited states are possible in the Projected Shell Model (PSM) [1]. This novel shell model [2], designed for arbitrarily heavy systems, starts from a deformed mean-field solution, transforms the basis states from the intrinsic to the laboratory frame through angular–momentum-projection [3], builds the configurations in the projected space, and then performs shell-model diagonalization in the laboratory frame. The obtained states are eigenstates of spin and parity, and the well-defined wavefunctions can be used to calculate any observables.

In this presentation, we introduce algorithms of PSM for handling huge shell-model spaces, which is an impossible task for conventional shell models. Taking heavy, deformed nuclei as examples, we show how to solve the eigenvalue problem, H |Ψ> = E |Ψ>, to obtain microscopic NLD [4]. We discuss features found in our NLD calculation that are previously unnoticed. To demonstrate that other observables can also be obtained in the same model, gamma-ray strength functions [5], electron-capture rates [6], Gamow-Teller strengths of beta decay [7] for highly excited states are briefly discussed. We stress that both the current theory and limited experimental evidence tend to suggest that new types of ordered collective motion may emerge in regions that are normally considered chaotic.

[1] K. Hara and Y. Sun, Int. J. Mod. Phys. E4 (1995) 637.
[2] Y. Sun, Phys. Scr. 91 (2016) 043005.
[3] M. Guidry and Y. Sun, Symmetry, Breaking Symmetry, and Topology in Modern physics: A First Course (Cambridge University Press, 2022).
[4] J.-Q. Wang, S. Dutta, L.-J. Wang, Y. Sun, Phys. Rev. C 108 (2023) 034309.
[5] F.-Q. Chen, Y.-F. Niu, Y. Sun, M. Wiedeking, to be published.
[6] L. Tan, Y.-X. Liu, L. J. Wang, Z.- P. Li, Y. Sun, Phys. Lett. B 805 (2020) 135432.
[7] L.-J. Wang, L. Tan, Z.-P. Li, G. W. Misch, Y. Sun, Phys. Rev. Lett. 127 (2021) 172702.

Speaker: Prof. Yang Sun (Shanghai Jiao Tong University)

Presentation_ID448_Sun.pptx

57 Review of magnetic- and antimagnetic-rotational structures in nuclei

This work is an update of the 2000 publication of magnetic-rotational bands by Amita et al. [1], followed by an unpublished update of 2006 [2], and reviews detailed experimental data extracted from original publications for 228 magnetic-rotational (MR or Shears) structures spread over 117 nuclides, and 38 antimagnetic-rotational (AMR) structures in 28 nuclei, with a brief commentary about each band. Many of these nuclei are located at or near the semi-magic nucleon numbers, mostly for protons. For example, 88 MR bands are currently known for the Pb (Z=82) nuclei, and 27 AMR band in Pd, Cd and In nuclei. It is interesting that the proton magic numbers appear to play a major role in the MR phenomenon, which seems less well understood. A brief discussion of the salient features of the MR and AMR bands and their theoretical interpretation has been presented in the present review. The tables contain gamma-ray energies, associated level energies with spins and parities, level lifetimes, B(M1), B(E2), and B(M1)/B(E2) ratios, the latter four when available, and probable spherical quasiparticle configurations. We find that many bands claimed in the literature as MR and AMR bands still have tentative assignments, as level lifetimes, thus B(M1) and B(E2) values, for a large number of MR and AMR bands, which can potentially provide critical criteria for firm identification of such structures, are lacking. Additionally, theoretical model calculations for many of these bands, which could provide insight for a better description of nuclear structure, are also lacking in literature. While this review is mainly based on original research articles, nuclear structure databases ENSDF [3], XUNDL [4], and NSR [5] databases have been consulted for completeness. The literature cut-off date is August 11, 2024.

References

[1]Amita, A.K. Jain, and B. Singh, At. Data and Nucl. Data Tables, 74, 283 (2000).
[2]Amita, B. Singh, P. Agarwal, and A.K. Jain (Preprint, 2006),
https://www.nndc.bnl.gov/ensdf/evalcorner/pdfs/MR_shear_bands_dec06.pdf
[3]T.W. Burrows, Nucl. Instrum. Meth. Phys. Res. A 286, 595 (1990), Evaluated Nuclear Structure Data File (ENSDF database), http://www.nndc.bnl.gov/ensdf/
[4]XUNDL database, http://www.nndc.bnl.gov/ensdf/ensdf/xundl.jsp
[5]B. Pritychenko, E. Betak, M.A. Kellett, B. Singh, and J. Totans, Nucl. Instrum. Meth. Phys. Res. A 640, 213 (2011), Nuclear Science References (NSR) database, http://www.nndc.bnl.gov/nsr/

Speaker: Sushil Kumar (Akal University Talwandi Sabo)

58 Measurements of octupole collectivity in $^{144}$Ba via Coulomb excitation

Identifying nuclei that have a stable octupole deformation is crucial to the search for odd mass isotopes with atomic electric-dipole moments. Observation of an atomic electric dipole moment would indicate CP violation due to physics beyond the standard model. Mean-field calculations predict that octupole correlations are enhanced for certain nuclei in the actinide and lanthanide regions of the nuclear chart. The magnitude of octupole correlations can be inferred from the structure of nuclear energy levels and enhanced E1 transition strengths, although shell effects can complicate the interpretation of such data. The E3 moment is the observable that provides the most unambiguous measure of enhanced octupole correlations, being insensitive to single particle effects. Direct measurements of the E3 moments in $^{222,224,226}$Ra show they exhibit stable octupole deformation, while $^{228}$Ra behaves as an octupole vibrator [1]. Current experimental B(E3) data in the lanthanide region however is scarce. Measurements reported for the B(E3) of $^{144,146}$Ba [2,3] are significantly enhanced over theory and are consistent with octupole deformation, but have very large associated uncertainties.

To address this, a Coulomb excitation experiment on $^{144}$Ba was conducted at the HIE-ISOLDE facility at CERN in November 2024, with aims to re-measure the B(E3). A beam of $^{144}$Ba was produced by bombarding a primary uranium carbide target with a 1$\mu A$ proton beam. The $^{144}$Ba beam was re-accelerated to 4.52 MeV/u, optimised to maximise the Coulomb excitation cross section while staying within Cline’s safe energy criterion, ensuring excitation occurs purely via the electromagnetic interaction. The beam was then focused onto a secondary $^{208}$Pb target, with a silicon DSSSD placed downstream to detect the scattered target and projectile. The target was surrounded by the Miniball spectrometer, consisting of seven HPGe clusters used to detect the de-excitation of both the target and projectile. Thanks to the intense beams delivered by ISOLDE the measurement was successful, despite a significant portion of the beam consisting of isobaric contaminants. The multiple Coulomb-excitation code GOSIA will be used to provide a direct measurement of both the E2 and E3 moments. The greater number of statistics observed for the $^{144}$Ba (3$^{-}$→ 2$^{+}$) transition, compared to the previous measurement [2], suggests that the B(E3) transition strength in $^{144}$Ba will likely be determined with improved precision. Analysis of the data is ongoing, and the current status will be presented.

[1] P. A. Butler et al., "Evolution of Octupole Deformation in Radium Nuclei from Coulomb Excitation of Radioactive $^{222}$Ra and $^{228}$Ra Beams," Physical Review Letters, vol. 124, no. 4, p. 042503, Jan. 2020, doi: 10.1103/PhysRevLett.124.042503.
[2] B. Bucher et al., "Direct Evidence of Octupole Deformation in Neutron-Rich $^{144}$Ba," Physical Review Letters, vol. 116, no. 11, p. 112503, Mar. 2016, doi: 10.1103/PhysRevLett.116.112503.
[3] B. Bucher et al., "Direct Evidence for Octupole Deformation in $^{146}$Ba and the Origin of Large (E1) Moment Variations in Reflection-Asymmetric Nuclei," Physical Review Letters, vol. 118, no. 15, p. 152504, Apr. 2017, doi: 10.1103/PhysRevLett.118.152504.

Speaker: BEN JONES (University of Liverpool)

Presentation_ID636_Jones.pdf

Presentation_ID636_Jones.pptx

59 Isomeric decay of 157-Sm populated via novel fragmentation of 170-Er

The isomeric decay of $^{157}_{\,\,62}$Sm was observed for the first time during experiment G-22-00100-1.1-S (S100), conducted at GSI in the spring of 2024. A novel $^{170}$Er beam was fragmented at 1.08 GeV/u on a 6 gm/cm$^{2}$ $^9$Be target. The fragmentation products were separated and identified using the FRagment Separator (FRS) and implanted in the Advanced Implantation Detector Array of the Decay Spectroscopy setup at the S4 focal plane of the FRS. A suite of 12 triple-cluster germanium detectors and 36 fast-timing LaBr$_3$ detectors were employed to study the γ-decay of the stopped fragments. Here, we present the preliminary results for the level scheme and lifetime of the isomeric decay of $^{157}$Sm. The measured level scheme is incorporated with those of recent studies where excited states of $^{157}$Sm were populated via $\beta$-decay [2] and proton induced fission [3].

[1] Li, G. S. et al., Nucl. Instrum. and Methods Phys. Res. A 987, 164806 (2021)
[2] Hartley, D.J. et al., Phys. Rev. C 110, 044319 (2024)
[3] Zachary, C.J., 2019. New Insights into the Structure of Neutron-rich Nuclei $^{157}$Sm, $^{163}$Gd, and $^{163}$Tb (Ph.D.).

keywords: isomeric decay, fragmentation, high-resolution spectroscopy, FAIR Phase-0

Speaker: Jeroen Bormans (GSI / TU Darmstadt)

Presentation_ID638_Bormans.pdf

60 Octupole phonon excitations on the shell model states in medium and heavy nuclei

Large-scale nuclear shell-model calculations are performed in Xe, Cs, and Ba isotopes up to mass 142 (Z > 50 and N > 82) assuming tin-132 as a doubly magic core. All the single-particle levels in the one-major shells are considered [1]. For an effective two-body interaction, only one set of the multipole pairing and quadrupole-quadrupole interactions between neutrons and protons is employed and the strengths of the two-body interactions are set constant for all the nuclei considered. These interactions are phenomenologically determined to reproduce the experimental energy spectra in two-body systems. Single-particle energies are set constant for all the nuclei except the neutron intruder orbital. Electromagnetic transitions and moments are also calculated and excelent agreements are obtained.

In this mass region, octupole correlated states are found in the low-lying energy, for which the collective octupole vibrational motion is involved. These states are constructed by phenomenologically introducing a collective octupole-phonon built on top of each shell-model state. Octupole vibrational bandsnaturally emerge in this treatment.

[1] N. Yoshinaga et al., Phys. Rev. C 109, 064313 (2024).

Speaker: Prof. Naotaka Yoshinaga (Saitama University)

Presentation_ID107_yoshinaga.pptx

61 MONUMENT. Study of the properties of ordinary muon capture for neutrinoless double beta decay and more.

The large energy and momentum transfer of ordinary muon capture makes it an excellent tool to study the nuclear structure at conditions similar to neutrinoless double beta decay and benchmark the corresponding nuclear matrix elements. The MONUMENT collaboration is performing a set of muon capture experiments at the Paul Scherrer Institute in Switzerland. In the report the measurement principle, the setup and analysis of the obtained data performed with different targets are presented.
The experimental setup is an array of germanium detectors collecting the radiation produced by the interaction of negative muons with a target. Various methods of data processing, identification and selection of useful events will be considered in order to obtain total and partial muon capture probabilities, as well as the yields of muon capture reaction products in the various nuclei such as 48Ti, 136Ba, 76Se, 100Mo.

Speaker: Viacheslav Belov (JINR)

Presentation_ID434_Belov.pdf

62 Methods of the data analysis and preliminary results in the MONUMENT experiment

Search for the neutrinoless double beta decay (0nbb) is one of the priority tasks of modern physics. Its discovery would play a fundamental role not only for neutrino physics itself, but also for particle physics and cosmology. To determine the effective mass of the Majorana neutrino from the measured probabilities ​​of 0nbb decay, it is necessary to know the value of the corresponding nuclear matrix element (NME) with sufficient accuracy. Up to date, theoretical NME calculations give results that vary by a factor of 2–3, depending on the shell model used in evaluation. The obtained results in our project would be drastically important for checking the accuracy of theoretical calculations of NME.
Since 2021, a large amount of data has been collected using different isotopes (daughters of 0n2b) as a target.This poster will present the main methods of data selection and identification used in our analysis in order to obtain partial muon capture rates in different isotopes. The Multi-detector data acquisition system together with an independent monitoring system allowed us to qualitatively differentiate the events recorded by our setup. The obtained preliminary results will be presented as well.

Speaker: Mariia Fomina (Joint Institute for Nuclear Research)

Presentation_ID601_Fomina.pdf

16:00 Break

Parallel Session: 2_Nuclear Structure (3)

Convener: Elena Litvinova (Western Michigan University)

63 The 76Cu conundrum remains unsolved

Isomers are intriguing excited nuclear states with long half-lives, sometimes comparable or even longer than that of the ground state of the nuclide. The reasons for these long half-lives are diverse, such as large angular momentum differences between states or shape coexistence [1,2]. There is a strong ongoing experimental effort to measure and understand the underlying nuclear structure effects that explain their existence, since they have a significant impact on other research fields and practical uses. These applications range from medicine to potential nuclear batteries or clocks. Isomers also play a key role in stellar nucleosynthesis and it has been suggested that some superheavy elements could be more stable in isomeric states than in their ground states, similar to $^{180m}$Ta.

Near the doubly-magic nucleus $^{78}$Ni ($Z=28$, $N=50$), there has been a decades-long debate on the existence of a long-lived isomer in $^{76}$Cu [3]. A recent mass measurement claimed to have settled the debate, by measuring the excitation energy of the isomer and shedding light on the structure of the nuclide [4].

In this work, performed at the Isolde Decay Station at CERN, we present more accurate and precise values of the half-lives of the isomeric and ground states in $^{76}$Cu. Our findings suggest that both states have very similar half-lives, in disagreement with the literature values, implying that they cannot be differentiated by their decay curves. These results raise more questions than they answer, reopening the debate and showing that the structure in $^{76}$Cu is still not fully understood.

[1] Walker, P., Dracoulis, G. Energy traps in atomic nuclei. Nature 399, 35–40 (1999).

[2] Philip Walker and Zsolt Podolyák 2020 Phys. Scr. 95 044004

[3] J. A. Winger et al, Structure of 76Zn from 76Cu decay and systematics of neutron-rich Zn nuclei, Phys. Rev. C 42 (1990) 954–960.

[4] L. Canete et al, Long-sought isomer turns out to be the ground state of 76Cu, Phys. Lett. B 853 (2024) 138663.

Speaker: Bruno Olaizola (IEM - CSIC)

Presentation-ID7286-Olaizola.pdf

64 Investigating the deformation of the intruder isomeric $1/2^+$ state in $^{79}$Zn (N=49) via Coulomb excitation

For nuclei with $N$ around 50, several pieces of evidence supporting shape coexistence close to $^{78}$Ni have been found [1-3]. In particular, the $\sim$940-keV $1/2^+$ isomeric state in $^{79}$Zn, first observed in a $(d,p)$ transfer measurement [4] and recently studied with high-precision mass measurements [3], has been interpreted as an intruder state, related to neutron excitations across $N=50$. Laser-spectroscopy measurements found a large isomeric shift for this state with respect to the $^{79}$Zn $9/2^+$ ground state indicating a significantly larger mean squared charge radius [2]. Assuming an axial quadrupole shape, this would suggest a deformation of $\beta=0.22$, considerably larger than $\beta=0.15$ of the ground state, and would imply a significant mixing from the $2d_{5/2}$ neutron orbital. Alternatively, the larger radius could be due to the enlarged spherical shape coming from the contribution of the higher major oscillator shell orbital $3s_{1/2}$ [5-6].

In order to probe the quadrupole deformation of the intruder isomer in $^{79}$Zn and to understand the nature of its wave function, we used a post-accelerated $^{79}$Zn beam from ISOLDE that consisted of a mixture of nuclei in the $9/2^+$ ground state and the $1/2^+$ isomeric state, to populate excited states built on these two different configurations via Coulomb excitation on $^{196}$Pt and $^{208}$Pb targets. In the experiment, $\gamma$ rays were detected by the Miniball array [7], while scattered projectiles and beam recoils by an annular DSSD detector placed at forward angles.

We will present preliminary results of this study, providing evidence for strong Coulomb excitation of states built on the intruder isomer, and for the observation of new transitions that fill the gaps in the known level scheme of $^{79}$Zn. We will discuss their possible implications in the context of the deformation of the $1/2^+$ isomer in $^{79}$Zn, and of the $^{80}$Zn ground state.

[1] A. Gottardo et al., Phys. Rev. Lett. 116, 182501 (2016)
[2] X. F. Yang et al., Phys. Rev. Lett. 116, 182502 (2016)
[3] L. Nies et al., Phys. Rev. Lett. 131, 222503 (2023)
[4] R. Orlandi et al., Phys. Lett. B 740, 298 (2015)
[5] J. Bonnard, A. Zucker, S. Lenzi, Phys. Rev. Lett. 116, 212501 (2016)
[6] J. Bonnard and A. Zucker, arXiv:1606.03345 (2016)
[7] N. Warr et al., Eur. Phys. J. A 49, 40 (2013)

Speaker: Filippo Angelini (INFN-LNL and University of Padova)

Presentation_ID037_Angelini.pdf

65 Status of in-beam $\gamma$-ray spectroscopy of neutron-rich scandium isotopes with N = 34 and 36

While new magic numbers for N = 32 and 34 have been established in the Ca isotopes, some evidence of deformation and complex particle-hole configurations have been found in nuclei approaching the N = 40 Island of Inversion. To establish these structural changes the information on the isotopic chains of Sc and Ti and the isotonic chains of N = 34 and 36 will be helpful.
The single-particle structure of protons and neutrons and the collective behavior of the neutron-rich $^{56,58}$Ti have been explored in an experiment at the RIBF/RIKEN in Japan. The exotic cocktail beams were produced by the projectile fragmentation and separated by the BigRIPS separator. The secondary reactions took place in the center of the newly designed HiCARI (High-Resolution Cluster Array at RIBF) for gamma-ray detection.
In this presentation, we give an overview of the experiment and the status of the analysis for the proton knockout reactions to populate $^{55,57}$Sc. Although the states in the former isotope are already known, the new preliminary data may shed some light on the collective nature, enabling lifetime measurements for the first time. In addition, we also present the first spectroscopic studies of $^{57}$Sc.

Speaker: Jiseok Kim (Korea University)

Presentation_ID236_Kim.pdf

66 Structure of neutron-rich Ge isotopes in vicinity of the double-magic 78Ni nucleus.

Experimental studies of excited states have been performed to probe the evolution of the shell structure in neutron-rich nuclei. In the case of N=50 isotopes from $^{90}Zr$ to $^{78}Ni$, specific excited states correspond mainly to neutron excitations across the N=50 gap. Thus, the evolution of the excitation energy of these states, particularly in the $^{82}Ge$ nuclei, enables to deduce the size of the N=50 gap. In addition, information on the collective or single-particle (particle - hole configuration) nature may be obtained in odd Ge isotopes on both sides of the N=50 gap ($^{81}Ge$ and $^{83}Ge$).

A large data set of neutron-rich nuclei is produced in a fusion-fission reaction with $^{238}U$ beam (at 6.2 MeV/u) impinging a $^{9}Be$ target. The several fission fragments are selected unambiguously (A and Z identification) by the VAMOS++ spectrometer. The prompt gamma rays are detected in coincidence with the fission fragments by the AGATA array composed of 8 triple-clusters.

The experimental results are compared with the most advanced shell-model calculations using the most updated interaction for this region in the nuclear chart.

The structure of these N=49 and N=51 nuclei has already been investigated through beta-decay, Coulomb excitation, and nucleon-transfer experiments. However, their high-spin states have not yet been studied using prompt gamma-ray spectroscopy. Indeed, for the first time, the level schemes of various neutron-rich Ge isotopes (N=49, N=50, and N=51) and 79Zn (N=49) will be presented and discussed in the light of theoretical calculations.

Collaboration:
G. Duchêne, J. Dudouet, D. D. Dao, F. Nowacki, E. Clément, A. Lemasson, C. Andreoiu, A. Astier, G. de Angelis, G. de France, C. Delafosse, I. Deloncle, Z. Dombradi, C. Ducoin, A. Gadea, A. Gottardo, D. Guinet, B. Jacquot, P. Jones, T. Konstantinopoulos, I. Kuti, A. Korichi, S. M. Lenzi, G. Li, F. Le Blanc, C. Lizarazo, R. Lozeva, G. Maquart, B. Million, C. Michelagnoli, D. R. Napoli, A. Navin, R. M. Pérez-Vidal, C. M. Petrache, N. Pietralla, D. Ralet, M. Ramdhane, M. Rejmund, O. Stezowski, C. Schmitt, D. Sohler, and D. Verney.

Speaker: Francois Didierjean (University of Strasbourg - IPHC)

Presentation_ID269_Didierjean.pdf

Presentation_ID269_Didierjean.pptx

67 Competing nuclear shapes in exotic nuclei: proton and neutron transition matrix elements in neutron rich Ni isotopes by high resolution spectroscopy

F. Galtarossa$^1$, G. de Angelis$^2$, T. Marchi$^2$, L. Scomparin$^3$, T. Baumann$^4$, D. Bazin$^4$, A. Gade$^4$, A. Gottardo$^2$, P. R. John$^5$, M. Klintefjord$^6$, K. Kolos$^7$, S. M. Lenzi$^5$, D. Mengoni$^5$, C. Michelagnoli$^8$, V. Modamio$^6$, D. R. Napoli$^2$, S. Noji$^4$, J. Pereira$^4$, F. Recchia$^5$, E. Sahin$^6$, J. J. Valiente-Dobón$^2$, K. Wimmer$^9$, D. Weisshaar$^4$, R. Zegers$^4$, M. Dupuis$^{10}$, Y. Tsunoda$^{11}$ and T. Otsuka$^{12}$.
$^1$ INFN Sezione di Padova, Padova, Italy, $^2$ INFN Laboratori Nazionali di Legnaro, Padova, Italy $^3$ Karlsruher Institut für Technologie, 76131 Karlsruhe, Germany $^4$ NSCL, Michigan State University - East Lansing (MI) 48824, USA, $^5$ Dipartimento di Fisica e Astronomia, Università di Padova, Italy, $^6$ Department of Physics, University of Oslo - Blindern, N-0316 Oslo, Norway, $^7$ Lawrence Livermore National Laboratory - Livermore, CA 94551, USA, 8 Institut Laue-Langevin (ILL) - 38042 Grenoble Cedex 9, France, $^9$ Instituto de Estructura de la Materia, CSIC - E-28006 Madrid, Spain, $^{10}$ CEA DIF, BP 12, 91680 Bruyères-le-Chatel, France, $^{11}$ Center for Nuclear Study, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan, $^{12}$ Department of Physics and Center for Nuclear Study, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.

Transition matrix elements in exotic nuclei provide an important avenue for studying changes in shell structure, core polarization mechanisms, shape coexistence and other aspects of nuclear structure far from the valley of stability. In the nuclear chart the Nickel isotopic chain offers a unique opportunity to study the interplay between single-particle and collective excitations in atomic nuclei, for which important observables are the energy of the first 2+ excited state in even-even nuclei and the reduced transition probability B(E2; 2+→0+). The B(E2) can be indirectly measured via Coulomb Excitation (Coulex) and proton inelastic scattering. Coulex, being a purely electromagnetic probe under specific experimental conditions, is sensitive only to the proton contribution. Proton inelastic scattering, on the contrary, can assess the contribution of neutrons to the collectivity, and, more importantly, the ratio between the proton and neutron matrix elements.
In two experiments performed at the National Superconducting Cyclotron Laboratory (NSCL) of the Michigan State University (MSU) and at RIKEN (J) we measured the (p,p’) inelastic scattering and the Coulex of neutron-rich Ni isotopes 68,70,72Ni and 73,74,75Ni produced by induced fission at intermediate and relativistic energies. In the first case Radioactive Ni beams impinged at 80 MeV/u on a liquid hydrogen target and the scattered beam particles were detected in the S800 spectrometer while the coincident γ rays in the GRETINA γ-ray array. In the second experiment secondary Ni beams, after separation in the BIG RIPS spectrometer, were Coulomb excited before implantation in the position sensitive Si detector. Gamma rays were detected by the DALI2 scintillator array. In the first case the high γ-ray energy resolution of the GRETINA array allowed to identify yrast and yrare states in these nuclei and, from the measurement of the inelastic scattering cross section, to deduce their deformation length δ. Using the one-body density matrices from Monte Carlo Shell model, the combined results allowed to extract proton/neutron matrix elements for the different competing shapes. This experiment is complementary to a series of recent measurements in the region [1,2,3] and the results, which will be presented at the conference, help drawing a more complete picture on the nuclear structure evolution along the Z = 28 proton shell closure. Future programs using multinucleon transfer reactions at LNL with stable and radioactive secondary beams from the SPES facility will also be presented.
[1] N. Aoi, et al., Phys. Lett. B 692 (2010) 302.
[2] M. L. Cortés, et al., Phys. Rev. C 97, 044315 (2018).
[3] A. Gottardo et al., Phys. Rev. C 102, 014323 (2020).

Speaker: Giacomo de Angelis (INFN Laboratori Nazionali di Legnaro)

Parallel Session: 2_Hadron Structure and Reactions

Convener: Homeoyng Choi (Kyungpook National University)

68 Near-threshold photoproduction of J/$\psi$ of a proton with the CLAS12 experiment

The photo-production of vector mesons off the proton has long been established as an important tool to access the gluon content of the nucleon. In particular, the photo-production of J/$\psi$ near the threshold energy has been related to the Gravitational Form Factors of the gluons which provide information about the mass and the force distributions in the nucleon. In this talk, I will present results on the near-threshold photoproduction of J/$\psi$ using data taken in 2018 and 2019 by the CLAS12 detector at Jefferson Lab, using a 10.6 GeV electron beam on a liquid-hydrogen target. This measurement is expected to provide direct insight on the gluons distribution inside the proton.

Speaker: Pierre Chatagnon

Presentation_ID170_Chatagnon.pdf

69 Generalized Parton distributions of the kaon and pion within the nonlocal chiral quark model

In this talk, we discuss the properties of generalized parton distributions (GPDs) for the kaon and pion within the framework of the nonlocal chiral quark model (NLχQM). The valence quark GPDs of the kaon and pion are analyzed in detail with respect to their momentum fraction x and skewness ξ dependencies in the DGLAP and ERBL regions. Due to explicit chiral symmetry breaking, we observe a significant distortion of the kaon quark GPDs in the ERBL domain near $\xi=1$, which affects the D-term of the kaon. Through polynomiality, we obtain the gravitational form factors of the kaon and pion, analyze them in detail, and compare them with results from other effective models.

Speaker: Dr Hyeon-Dong Son (Inha University)

Presentation_ID403_Son.pdf

70 Measurement of beam-polarized Deeply Virtual Compton Scattering observables with $e\gamma$ detection @ CLAS12

In the context of nucleon structure studies, Generalized Parton Distributions (GPDs) are crucial for understanding the correlation between the longitudinal momentum and the transverse position of partons inside the nucleon. A privileged channel for GPDs studies is the Deeply Virtual Compton Scattering (DVCS) process whose experimental observables can provide access to GPDs through spin dependent asymmetries. Although detecting all final state particles is preferred for selecting DVCS events, DVCS identification can be ensured by requiring the detection of only two final state particles as the missing particle can be reconstructed from conservation laws. In this work, we present new Beam Spin Asymmetry and preliminary cross-section measurements of proton-DVCS in the $e\gamma$ topology from experimental data taken by the CLAS12 detector at Jefferson Lab. Besides, we show that relying on $e\gamma$ detection and Machine Learning techniques boosts statistics and gives access to a larger phase space than the proton-detected topology.

Speaker: Juan Sebastian Alvarado (Université Paris-Saclay - IJCLab)

Presentation_ID168_ALVARADO.pdf

71 Quark confinement in tetraquark systems

We discuss a novel formulation of the quark confinement potential in the quark model viewpoint. The new formula contains the multi-body string-like potential, that allows hidden-color configurations besides two-meson states. We apply this formulation to the newly discovered $cc\bar c\bar c$ tetraquark states and find an interesting spectrum for the system. We suggest some bound states as well as resonances in the S-wave $cc\bar c\bar c$.
Ref. G.J. Wang, M. Oka, D. Jido, Phys. Rev. D108, L071501 (2023), ArXiv: 2307.04310

Speaker: Makoto Oka (RIKEN)

M.Oka-2025INPC.pdf

Parallel Session: 2_Hot and Dense Nuclear Matter

Convener: Nu Xu (LBNL)

72 Recent results from Beam Energy Scan, looking for a critical point in the QCD phase diagram

The Quark Gluon Plasma (QGP) is been studied with high-energy heavy-ion collisions at various experimental facilities in order to investigate the properties of the phase transition and the QCD phase diagram, from the high-temperature phase such as early universe to the high-density phase such as neutron and compact stars, where the first order phase transition and critical end point are expected towards the high baryon density area in the phase diagram, which are being actively searched at Relativistic Heavy-Ion Collider (RHIC) at BNL and several on-going and future facilities. The recent experimental results from the Beam Energy Scan Program (BES-I and BES-II) will be shown and discussed especially on fluctuation, flow and correlation in this presentation especially related to the first order phase transition and critical end point.

Speaker: ShinIchi Esumi (Univ. of Tsukuba)

Presentation_ID328_Esumi.pdf

73 Anatomy of critical fluctuations in hadronic matter

I discuss the fluctuations of the net-baryon number near the liquid-gas and chiral phase transitions. I use the parity doublet model to investigate the qualitative properties and systematics of the first- to fourth-order cumulants and their ratios. I show that the fluctuations of the positive-parity (e.g. protons) and negative-parity baryons do not qualitatively reflect the fluctuations of the total net-baryon number density at the phase boundaries of the liquid-gas and chiral phase transitions. I qualitatively compare the factorial cumulants for the net-proton and net-baryon number and point to the importance of the non-trivial correlations between various baryon species, in particular to the correlations between protons and neutrons as well as positive- and negative-parity baryonic chiral partners.

References:
- M. Marczenko, K. Redlich, C. Sasaki, arXiv:2410.21746 [nucl-th]
- M. Marczenko, Phys. Rev. D 110 (2024) 1, 014018
- V. Koch, M. Marczenko, K. Redlich, C. Sasaki, Phys.Rev.D 109 (2024) 1, 014033

Speaker: Michał Marczenko (University of Wrocław)

Presentation_ID240_Marczenko.pdf

74 Femtoscopy of Strange Baryons in Heavy-ion Collisions at RHIC-STAR

Femtoscopy is a powerful technique to study the information about the space-time evolution of the emitting source and final state interactions in heavy-ion collisions. Femtoscopy analysis of strange baryons, which contain strange quarks, offer an important role of studying the hyperon-nucleon ($Y$-$N$) and hyperon-hyperon ($Y$-$Y$) interactions. In addition, it can also be used to search for the bound state of strange dibaryons, which have long been a subject of interest in understanding the strong interaction beyond conventional hadrons.

In this talk, we will present the femtoscopy analysis of strange baryons, including $\Lambda$-$\Lambda$, $p$-$\Xi^{-}$, $p$-$\Omega^{-}$ pairs in Isobar collisions (Ru+Ru, Zr+Zr) at $\sqrt{s_\mathrm{NN}}$ = 200 GeV and $p$-$\Lambda$ in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 3 GeV. The correlation functions are analyzed within the Lednicky-Lyuboshitz formalism. The extracted scattering length and effective range will be compared with recent Lattice QCD and effective theory model calculations. The physics implications for the formation of strange dibaryon bound state will also be discussed.

Speaker: Boyang Fu (Central China Normal University)

Presentation_ID347_Fu.pdf

75 Rapidity Dependence of Proton Higher-Order Cumulants in $\sqrt{s_{NN}}$ = 3.2, 3.5 and 3.9 GeV Au+Au Collisions by STAR

Fluctuations of conserved quantities are proposed as a useful observable to study the QCD phase structure including the search for the first-order phase boundary and critical point [1]. Lattice QCD calculations have shown that there is no critical point for $\mu_B \le$ 450 MeV and few phenomenology models calculations have shown that the critical point could be at temperature of $T \sim$ 100 MeV and baryonic chemical potential of $\mu_B \sim$ 600 - 650 MeV [2-6].

Rapidity dependence of the higher order cumulant ratios have been argued to be sensitive to the QCD critical point [7]. In this talk, we will report rapidity dependence of both higher order cumulants and factorial cumulants of proton multiplicity distribution, up to $6^{TH}$ order from Au+Au collisions, at $\sqrt{s_{NN}}$ = 3.2, 3.5 and 3.9 GeV (699 $\ge \mu_B \ge$ 633 MeV) from the STAR experiment at RHIC. Collision centrality dependence of these rapidity distributions and relevant ratios will be discussed. In addition, the results will be compared with the calculations from transport model UrQMD.

[1] STAR Note, https://drupal.star.bnl.gov/STAR/starnotes/public/sn0598.
[2] M. Hippert et al., (2023), arXiv:2309.00579 [nucl-th].
[3] W.-j. Fu et al., Phys. Rev. D 101, 054032 (2020).
[4] P. J. Gunkel et al., Phys. Rev. D 104, 054022 (2021).
[5] G. Basar, Phys. Rev. C 110, 015203 (2024).
[6] D. A. Clarke et al., (2024), arXiv:2405.10196 [hep-lat].
[7] B. Ling et al., Phys. Rev. C 93, 034915 (2016).

Speaker: Xin Zhang (Institute of Modern Physics, Chinese Academy of Sciences)

Presentation_ID255_Xin.pdf

76 Flow measurements of hyper- and light-nuclei in Au+Au collisions at 3.0 GeV at RHIC

Studying hyper-nuclei yields and their collectivity can shed light on their production mechanism as well as the hyperon-nucleon interactions. Heavy-ion collisions from the RHIC beam energy scan phase II (BES-II) provide an unique opportunity to understand these at high baryon densities.
In this presentation, we report on the directed flow ($v_{1}$) and the elliptic flow ($v_{2}$) of hyper-nuclei, including $\Lambda$, $^{3}_{\Lambda}{\rm H}$, $^{4}_{\Lambda}{\rm H}$ and $^{4}_{\Lambda}{\rm He}$, using approximately 2 billion minimum-bias events from Au+Au collisions at $\sqrt{s_{NN}}$ = 3.0 GeV, collected by the STAR experiment in the fixed-target mode during BES-II. The large event statistics will enable detailed differential flow measurements of hyper-nuclei in rapidity (y) and transverse momentum ($p_{\rm{T}}$), and extend $v_{2}$ measurements to $^{3}_{\Lambda}{\rm H}$, $^{4}_{\Lambda}{\rm H}$ and $^{4}_{\Lambda}{\rm He}$. These hyper-nuclei results are compared to that of light-nuclei including p, d, t, $\rm ^{3}He$ and $\rm ^{4}He$. Finally, these results are compared with calculations from a hadronic transport model.

Speaker: Junyi Han (Central China Normal University)

Presentation_ID295_Han.pdf

77 Light nuclei collective flow in Au+Au Collisions from STAR BES-II experiment

Study of light nuclei flow in heavy-ion collisions provides valuable insights
into their production mechanisms and the underlying collision dynamics, making it of
particular interest for both theoretical and experimental
research.
Previous measurements by the STAR experiment have shown the light nuclei directed
flow $v_1$ follow a mass number scaling at $\sqrt{s_{NN}}=$3 GeV[1].
At the same time there is a hint that the deuteron $v_1$ slope shows an
opposite sign compared to that of the proton at $\sqrt{s_{NN}}>$7.7 GeV,
which is in conflict with the nucleon coalescence picture[2].

In this talk, we will show measurements of directed and elliptic flow ($v_2$) for
light nuclei (deuteron, triton, $^{3}$He and $^{4}$He) in Au+Au collisions
at $\sqrt{s_{NN}}=$3.0-4.5 GeV,
along with new precision measurements of $v_1$
of deuterons and anti-deuterons at $\sqrt{s_{NN}}=$7.7-19.6 GeV by the
STAR experiment at RHIC from the Beam Energy Scan Phase - II.
The rapidity and transverse momentum dependence of flow will
be presented and compared with those of protons and anti-protons.
These results will also be discussed within the framework of
nucleon coalescence.

[1] M.S. Abdallah ${\it et\ al.}$ (STAR Collaboration),
Phys. Lett. B ${\bf 827}$, 136941 (2022)
[2] J. Adam ${\it et\ al.}$ (STAR Collaboration),
Phys. Lett. B ${\bf 102}$, 044906 (2020)

Speaker: Xionghong He (nstitute of Modern Physics, Chinese Academy of Sciences)

Presentation_ID546_HE.pdf

Parallel Session: 2_New Facilities and Instrumentation

Convener: Hiroyoshi Sakurai (RIKEN Nishina Center)

78 Perspectives for low-energy nuclear-physics experiments at the SPIRAL2-S3 facility

The SPIRAL2 facility is a new research infrastructure in GANIL powered by its superconducting linear accelerator of light and heavy ions which is currently in operation. The Super Separator Spectrometer (S$^3$) is one of the research facilities aimed at producing exotic nuclei by fusion-evaporation reactions with the accelerated heavy-ion beams, enabling their separation from the primary beam and their delivery to a focal-plane experimental installation [1]. The S$^3$Low Energy Branch (S$^3$-LEB) is the first focal-plane experiment which will use beams from S$^3$, wto stop the fusion-evaporation products in a gas-filled catcher and study their nuclear properties at very low energy.

The key feature of the S$^3$-LEB experiment is the implementation of the in-gas laser ionization and spectroscopy (IGLIS) technique [2], which means that the radioactive nuclei entering the gas catcher from S$^3$ will be neutralized, extracted to a vacuum chamber by a supersonic gas jet, to be then selectively re-ionized in the jet by wavelength-tunable lasers. The photo-ions will be delivered to a series of setups which will either determine their mass, measure their decay radiation, or perform ion counting. The latter mode can be combined with scans of the wavelength of one of the lasers acting in the jet to perform very sensitive measurements of laser spectroscopy. Together, all the techniques available at S$^3$-LEB will allow determining a wide range of low-energy nuclear properties, including the binding energies, mean-square charge radii and static electromagnetic moments, as well as half-lives and decay schemes.

The S$^3$-LEB setup has been commissioned off line with stable isotopes [3, 4] and is now installed at the focal plane of S$^3$, in preparation for on-line commissioning. This contribution will present the fundamentals of the IGLIS technique and its implementation at S$^3$-LEB, as well as results of laser spectroscopy and mass spectrometry from the off-line commissioning of the setup. Ongoing developments and perspectives for experiments with radioactive ion beams will also be discussed.

[1] F. Déchery et al., Nucl. Instrum. Meth. B 376, 125-130 (2016)
[2] R. Ferrer et al., Nat. Comm. 8, 14520 (2017)
[3] J. Romans, et al., Nucl. Instrum. Meth. B 536, 72 (2023)
[4] A. Ajayakumar, et al., NIM B 539, 102 (2023)

Speaker: Vladimir Manea (IJCLab-IN2P3-CNRS, France)

Presentation_ID439_Manea.pptx

79 Development of the Laser Systems for the Laser Spectroscopy in Exotic Nuclei Research

Laser spectroscopy techniques can simultaneously measure multiple fundamental properties of atomic nuclei (spins, electromagnetic moments, charge radii) by probing the hyperfine structure (HFS) and isotope shift of atomic/ionic energy levels [1]. Collinear Laser Spectroscopy is one of the approaches to measure the HFS spectrum, based on laser-induced fluorescence (LIF) and/or resonance ionization spectroscopy (RIS), and thus requires the use of narrow-band CW (continuous wave) laser, narrow-band and multiple broad-band pulse lasers.

Our group has recently developed a collinear laser spectroscopy system, which could measure the HFS spectrum using both LIF and RIS methods, and thus has high demands for the laser systems [2-4]. Therefore, a compact laser system, including narrow-band CW laser and its frequency-doubling, broadband pulse lasers and its 2nd/3rd/4th harmonic generation, high-power YAG lasers, as well as the frequency-stabilization and calibration system have been installed and tested. In addition to these commercial lasers, a home-made injection-locked cavity [5] including 2nd/3rd/4th harmonic generation to produce narrowband pulse laser, and the Pockel cell system to produce the narrow-band chopping laser beam have recently been developed and fully tested. These laser systems have been successfully applied to the high-resolution laser spectroscopy measurement using both LIF [2-3] and RIS [4] approaches.

In this presentation, the details of the laser systems and their application in laser spectroscopy experiments will be presented, along with the recently results from offline commissioning of stable nuclei and ongoing plans for online experiment of unstable nuclei.

[1] X.F. Yang, S.J. Wang, S.G. Wilkins et al., Prog. Part. Nucl. Phys, (2022)
[2] S. W. Bai, X. F. Yang, et al., Nucl. Sci. Tech, 33 (2022)
[3] S. J. Wang, X. F. Yang, et al., Nucl. Instrum. Methods Phys. Res. A, 33 (2022)
[4] P. Zhang, H.R. Hu, X.F. Yang , S.J. Wang, et al., Nucl. Instrum. Methods Phys. Res. B, (2023)
[5] M. Reponen, V. Sonnenschein, T. Sonoda, et al., Nucl. Instrum. Methods Phys. Res. A, 908 (2018)

Speaker: Mr Yangfan Guo (Peking University)

Presentation_ID17_Guo.pdf

80 Commissioning of a collinear resonance ionization laser spectroscopy setup

The fundamental properties of unstable nuclei are highly related to the nuclear structure and nucleon-nucleon interaction, which can thus be used to study various exotic structures of the unstable nuclei [1]. Laser spectroscopy technique is one of the powerful tools to study the nuclear properties (i.e. spins, moments and radii) by probing the hyperfine structure (HFS) and isotope shift of the corresponding atoms or ions [1].
To study the unstable nuclei at the radioactive ion beam facilities in China, our research group has developed a collinear resonance ionization laser spectroscopy setup [2] together with a compact Radio-frequency Quadrupole cooler and buncher (RFQ) [3]. The whole system has recently been commissioned successfully with stable Rb isotopes, demonstrating its ability for high-resolution and high-efficiency laser spectroscopy measurement of unstable nuclei with production yield lower than 1 k cps. The entire system will soon be applied to the Beijing Radioactive Ion-beam Facility (BRIF) [4] for the nuclear properties’ studies of neutron-rich Rb isotopes, produced from a UCx target.
In this talk, the technical details and the offline commissioning results of the collinear resonance ionization laser spectroscopy and the RFQ [4] will be presented, together with the anticipated results from the first online experiment on neutron-rich Rb isotopes planed at BRIF.

References:
[1] X. F. Yang, S. J. Wang, Wilkins S G, et al. Prog. Part. Nucl. Phys, 129, 104005 (2023).
[2] P. Zhang, H. R. Hu, X. F. Yang, et al. Nucl. Instrum. Methods Phys. Res. B. 541, 37-41 (2023).
[3] Carina Kanitz. Master’s thesis, Universitätsklinikum Erlangen (2021)
[4] T. J. Zhang, B. Q. Cui, Y. L. Lv, et al. Nucl. Instrum. Methods Phys. Res. B. 463, 123-127 (2020).

Speaker: Mr Hanrui Hu (Peking University)

Presentation_ID34_Hanrui.pdf

81 In-source laser spectroscopy for nuclear physics investigations at CERN-ISOLDE: Joining forces and new pathways

The Resonance Ionization Laser Ion Source RILIS [1], employing laser radiation in a hot cavity ion source directly coupled to an isotope production target, has become a principal method for provision of radioactive ion beams at facilities world-wide, such as at CERN-ISOLDE [2], -MEDICIS [3], TRUMF-ISAC [4] or RAON [5]. Step-wise resonant excitation and subsequent detachment of an electron via element-unique atomic shell transitions allows for highly efficient and chemically selective provision of the desired nuclide in the mass-separated ion beam.
Besides its application as part of the production infrastructure, RILIS is proven to be a highly sensitive tool itself for laser spectroscopy nuclear structure investigations on isotopes with low production and extraction yields [6]. These capabilities are based on and can even be further enhanced by extensive integration with dedicated experimental setups present on site that usually serve for conducting research on the provided radionuclides themselves. E.g., the ISOLDE Decay Station (IDS) [7] offers a tailored array of radiation detection methods to tag the produced ions against contamination, or the high mass resolution power of ISOLTRAP’s Multi-Reflection Time-of-Flight mass spectrometer [8] provides isobaric and even isomeric separation of the produced species. Recent highlights of these joined experimental programmes and an outlook to planned work is given, and the collaboration is presented.
Alongside the scientific output in the field of nuclear physics, we report on ongoing technical developments regarding key aspects of the in-source spectroscopy technique:
The specialized high selectivity RILIS variant LIST [9], employing spatial separation of the hot cavity from a dedicated laser ionization volume in a directly adjacent RF quadrupole unit, has been augmented with perpendicular laser beam access [10]. It allows for reduction of the effective Doppler broadening in interaction with the hot atom vapor, thus enhancing spectral resolution from experimental linedwidths in the GHz regime down to a few 100 MHz. First results outline its potential for further high-resolution applications, and greatly enhanced capabilities for isomer-selective provision of nuclides for experiments demanding highest ion beam purity.

References

[1] V. Fedosseev et al., Journal of Physics G: Nuclear and Particle Physics, 44(8) (2017), p. 084006
[2] R Catherall et al., J. Phys. G: Nucl. Part. Phys. 44 (2017) p. 094002
[3] C. Duchemin et al., Frontiers in Medicine, 8 (2021), p. 693682
[4] R. Li et al., Nucl. Instrum. Methods Phys. Res. B, 308 (2013), p. 74–79
[5] S. J. Park et al., J. Korean Phys. Soc. (2024)
[6] B.A. Marsh et al., Nature Physics, 14(12) (2018), p. 1163–1167
[7] http://isolde-ids.web.cern.ch/
[8] http://isoltrap.web.cern.ch/
[9] D.A. Fink et al., Nucl. Instrum. Methods Phys. Res. A, 344 (2015), p. 83–95
[10] R. Heinke et al., Nucl. Instrum. Methods Phys. Res. B, 541 (2023), p. 8–12

Speaker: Reinhard Heinke (CERN)

Presentation_ID537_Heinke.pptx

82 Status of the RAON ISOL facility

The ISOL (Isotope Separation On-Line) facility at RAON (Rare Isotope Accelerator complex for ON-line experiments) generates various rare isotopes (RIs) by bombarding protons onto heavy element targets such as uranium. Since March 2023, surface ionized RI beams of Li, Na, Al, Cs, and Ba have been successfully extracted using SiC and LaC2 targets at the ISOL facility.

The mass number was selected using an electromagnet system with a mass resolution (A/ΔA) of 400. The nuclides and intensities of the RI beams were identified by measuring and analyzing the gamma-ray spectra using the HPGe of the RIID (RI Identification) station.

Among the target-generated RIs, 25Na was selected and passed through the RFQ-CB (Cooler Buncher), then charge-bred to 5+ through the EBIS (Electron Beam Ion Source), and accelerated to an energy of 16.5 MeV/u at the SCL3 (Super Conducting Linac 3) post-accelerator. The accelerated RI beam was verified at KoBRA (Korea Broad acceptance Recoil spectrometer and Apparatus), completing the integrated operation test of the Cyclotron-ISOL-SCL3-KoBRA system. Additionally, Na and Al isotope beams were supplied to very low-energy experimental systems, such as MMS (Mass Measurement System) and CLS (Collinear Laser Spectroscopy), to conduct experiments including precise mass measurements and nuclear charge radius measurements.

This presentation will show the overall development progress and status of the RAON ISOL facility.

Speaker: Dr Hee-Joong Yim (IBS)

Presentation_ID690_YIM.pptx

83 PI-LIST at ISOLDE, CERN

Laser resonance ionization spectroscopy in the ion source coupled directly to the isotope production target has been proven to be a highly sensitive tool for nuclear structure investigations on isotopes with low production and extraction yields [1]. While the efficiency of this technique is unrivalled, the spectral resolution is ultimately limited by Doppler broadening. At the ion source temperature of ~2000 °C typically required for efficient operation, Doppler broadening results in a 1-10 GHz experimental resolution limit whereas precise measurements of nuclear magnetic and quadrupole moments often require resolving hyperfine structure splittings below the GHz regime.
A new laser ion source design has been implemented at ISOLDE recently to provide in-source spectroscopy capabilities down to experimental linewidths of 100 – 200 MHz, an order of magnitude below usual limitations. It is based on the high beam purity Laser Ion Source and Trap (LIST) [2, 3], featuring spatial separation of the hot cavity where potential ion beam contamination can arise from non-laser related ionization mechanisms such as surface ionization, and a clean laser-atom interaction region in an RFQ unit directly downstream, where solely element-selective laser ionization takes place. In the so-called Perpendicularly Illuminated LIST (PI-LIST) [4], a crossed laser/atom beam geometry reduces the effective Doppler broadening by addressing only the transversal velocity components of the effusing atom ensemble.
Following the integration of this device as the standard tool for high-resolution spectroscopy applications at the off-line mass separator facility at Mainz University [5, 6], we present its first on-line application at ISOLDE for nuclear structure investigations. Neutron-rich actinium isotopes in the region of assumed octupole deformation were probed, pinning down predictions of recent Energy Density Functional nuclear theories that incorporate reflection symmetry breaking [7].
The applicability of this technique to ISOL facilities in general, its limits especially in terms of significant efficiency loss, and technical implementation challenges are discussed.
[1] V. Fedosseev et al., J. Phys. G: Nucl. Part. Phys. 44 084006 (2017)
[2] D. Fink et al., Nucl. Instr. Meth. B, 317 B, 417-421 (2013)
[3] D. Fink et al., Phys. Rev. X 5, 011018 (2015)
[4] R. Heinke et al., Hyperfine Interact 238, 6 (2017)
[5] D. Studer et al., Eur. Phys. J. A 56, 69 (2020)
[6] T. Kron et al., Phys. Rev. C 102, 034307 (2020)
[7] E. Verstraelen et al., Phys. Rev. C 100, 044321 (2019)

Speaker: Asar AH Jaradat (CERN)

Presentation_ID231_JARADAT.pptx

Parallel Session: 2_Nuclear Astrophysics

Convener: Myung-Ki Cheoun (Soongsil University)

84 Neutron Star Mergers and Core collapse Supernovae as probes of the Nuclear Equation of State at High Density

There are two dynamical environments in Nature for which the densest forms of nuclear matter can be formed. These are: 1) during the merger of two neutron stars to form a black hole or the merger of a neutron star and a black hole; and 2) during the collapse of the core of a massive star to form a supernova or a black hole. This talk will highlight recent progress toward exploring equation-of-state effects in these two astrophysical environments. In particular, the possibility the possibility to probe the non-perturbative regime of quark matter are discussed along with insight into the complex interplay between the nuclear equation of state and the dynamics of core collapse supernovae.

Speaker: Grant Mathews (University of Notre Dame)

Presentation_ID743_Mathews.pptx

85 Toward solving the quantum kinetic transport of neutrinos in supernovae and neutron star mergers

Neutrinos play pivotal roles in determining the dynamics and nucleosynthesis in core-collapse supernova explosions and in binary neutron star mergers. However, a crucial element that has not been modeled consistently in the hydrodynamical simulations of these events is the flavor oscillations of neutrinos. It is, however, very challenging to include this element because of the associated non-linearity as well as the related temporal and spatial scales very different from the classical processes. In this talk, I'll mainly discuss our recent effort on the development of an effective classical transport model that can accurately capture perhaps the most prominent feature of neutrino oscillations in dense environments. I'll also talk about other aspects of neutrino oscillations and the related physical implications.

Speaker: Meng-Ru Wu (Institute of Physics, Academia Sinica)

Presentation_ID505_Wu.pdf

86 Deriving Progenitors of Extremely Metal-poor Stars with Nucleosynthesis Yields of Massive Stars

The most metal-poor stars offer a unique window into the chemical enrichment processes driven by Population III stars in the early Universe. The observed chemical abundance patterns in these stars provide critical constraints on the nucleosynthetic yields of metal-free progenitors, shedding light on their zero-age main-sequence masses. In this work, we analyze 406 very metal-poor stars with the latest high-resolution spectroscopic data from LAMOST and Subaru, presenting the most extensive investigation to date of the initial mass distribution of the first stars. The results challenge the traditional Salpeter initial mass function. By incorporating supernova explodability theory, we propose a modified power-law function that successfully accounts for the observed mass distribution, emphasizing that the initial metal enrichment arose predominantly from successful supernova explosions. Our findings suggest an extremely top-heavy or nearly flat initial mass function for Population III stars, characterized by a high explosion energy exponent. This study highlights the critical role of the nucleosynthesis in massive stars and explosion mechanisms in shaping the chemical evolution of the early Universe.

Speaker: Ruizheng Jiang (National Astronomical Observatories, CAS)

Presentation_ID427_Ruizheng.pdf

87 Uncovering the Origin of Galactic Ancient Accretion Relics

In the paradigm of hierarchical structure formation, we expect that numerous low-mass galaxies had been accreted to the Milky Way and leave their stellar debris throughout the stellar halo, which can be identified through searching for stellar substructures of similar orbital properties among metal-poor stars. However, only with the help of analyzing the detailed elemental abundances of their members, we are able to confirm the origin of these substructures and study the chemical evolution of their progenitors. Based on the huge LAMOST database, a number of dynamical tagged groups (DTGs) of very metal-poor stars have been identified by Yuan+2020, and high-resolution follow-up observations have been obtained for a number of interesting DTGs. This talk will present the abundance analysis of one new retrograde substructure, which provides valuable information on the origin of the most ancient components in the Galactic halo. Moreover, we have for the first time identified an extremely r-process enhanced (r-II) star in the relics of Gaia-Sausage-Enceladus (GSE), which provides us a great opportunity to compare the r-process pattern in different stellar systems, and may shed some light concerning the astrophysical condition of different site of r-process nucleosynthesis.

Speaker: renjing xie (National Astronomical Observatories, CAS (NAOC))

INPC_XIE_Renjing.pdf

88 Role of the light mass nuclear reactions to the r-process nucleosynthesis

We investigate the sensitivity of the r-process nucleosynthesis to light mass nuclear reactions. In the core-collapsed supernova and the collapsar, the light mass nuclear reactions play important roles. However, many light mass nuclear reactions with neutron-rich nuclei are still uncertain and the r-process sites are not fully understood. We use the Meyer's code for the reaction network calculation and include additional reactions rates near drip-line and update some reaction rates using recent experimental data. Then, we calculate the r-process nucleosynthesis in the core-collapsed supernovae for two different scenarios, the neutrino-driven wind model for the weak r-process and magnetohydrodynamic (MHD) jet model and also in the collapsar. The sensitivity of the r-abundances to these reactions are estimated when there is artificial increase of thermonuclear reaction rates. We discuss reaction network flows under the various conditions and importance of light mass nuclear reactions to understand the r-process nucleosynthesis.

Speaker: Dr Kyungil Kim (Institute for Rare Isotope Science, Institute for Basic Science)

Presentation_ID044_Kim.pdf

89 Discovering the most important temperatures of helium burning reactions in pair-instability supernova nucleosynthesis

Pair-instability supernovae (PISNe) are the final fates of massive stars with an initial mass ranging from 140-260 $M_\odot$. Due to the efficient $^{56}\mathrm{Ni}$ nucleosynthesis, PISNe can be very luminous phenomena. According to some previous works, not only the PISN progenitor evolution but also the PISN nucleosynthesis is affected from $^{12}\mathrm{C}(\alpha,\gamma)^{16}\mathrm{O}$ reaction rate strongly. However, these works are based on the reaction rate tables changed high or low in all temperatures despite the strong dependence of nuclear reactions on temperature. In this work, we considered the most important temperatures of helium burning reactions for $^{56}\mathrm{Ni}$ nucleosynthesis in PISN using Monte Carlo methods, specifically, we simulated the stellar evolution with randomized helium burning reaction rates, and we obtained the strong correlated temperature for these reactions. In this presentation, we will report the details of the results.

Speaker: Hiroki Kawashimo (The University of Tokyo)

Presentation_ID555_Kawashimo.pdf

Presentation_ID555_Kawashimo.pptx

Parallel Session: 2_Nuclear Reactions (1)

Convener: Nikolai Antonenko (BLTP, JINR)

90 First Proton Scattering Measurement using $^{40}$Ar beam at RAON

The proton elastic scattering using $^{40}$Ar beam was measured at low energies of 4.41, 5.84, and 8.13 AMeV using the KoBRA at RAON, which is the first physics experiment conducted at the RAON facility. This study aims to address limitations in phenomenological global optical model potentials (pGOMPs) by providing new experimental data and refining optical model potential parameters. Elastic scattering cross-sections were measured using a barrel-type silicon detector array, ELARK, with high angular resolution and broad coverage. The angular distributions of the elastic scattering were analyzed and compared with the Koning-Delaroche (KD) and Perey-Perey (PP) model calculation results. While the KD model showed reasonable agreement with the measured data at low angles, significant discrepancies were observed at larger angles. Refined optical model potentials were extracted using the SFRESCO code for parameter fitting, employing a chi-square minimization approach. This study is important to constrain the pGOMP parameters, particularly for low-energy scattering and reactions involving exotic isotopes. A detailed discussion and experimental results will be presented.

Speaker: Dahee Kim (Center for exotic nuclear studies, Institute Basic Science)

Presentation_ID565_Kim.pptx

91 Is Two-Nucleon Removal Reaction a Good Probe to Study np Correlations?

Developing a unified description of finite nuclei based on the underlying interactions between individual nucleons is a long-sought goal in nuclear physics. Two-nucleon removal reactions offer a promising tool to investigate nucleon-nucleon correlations, the fundamental ingredients in nuclear forces. A well-documented case is the electron-induced (e, e’pN) pair removal measurements on a C target at 4.6 GeV that selected high momentum transfer and large missing momentum events, suggesting that np pairs are about 20 times more prevalent than that like-nucleon pairs in short-range correlations. The systematic (e, e’pN) measurements with medium-to-heavy stable nuclei revealed a marked increase of the fraction of high-momentum protons with the neutron excess in nucleus.

To study how the np correlations evolve towards unstable nuclei with large isospin asymmetry, two-nucleon removal reactions in inverse kinematics are desired. In this talk, we will present the results of np removal from 12C with a Be target at 190 MeV/u together with the (p,2pn) reactions from neutron-rich nuclei at 250 MeV/u. Both measurements were performed at the RIBF with the BigRIPS and SAMURAI spectrometers. Significant two-step contributions from the evaporation were observed and subtracted in both cases. The partial cross sections to the individual final states of 10B were achieved and compared with the calculations using the ab-initio structure inputs. The reaction kinematics of (p,2pn) is under analysis and will be compared with the sequential picture discovered in the (p,3p) reactions.

Speaker: Hongna Liu (Beijing Normal University)

NN_removal_ID254_LIU.pptx

92 Charge-changing reaction study via the cross section measurements of 18O on carbon and lead at around 370 MeV/nucleon

We have performed precise measurements of the charge-changing cross sections (CCCSs) for $^{18}$O on carbon (C) and lead (Pb) targets at energies around 370 MeV/nucleon. We evaluate the contributions of nucleon-nucleon (NN) and the electromagnetic (EM) interactions to the CCCSs by explicitly considering the direct proton removal process, the charged particle evaporation (CPE) after neutron removal, and the EM excitation. Our results show that CPE contributes approximately 13% and 5% to the CCCS on C and Pb targets, respectively, while the EM is found to contribute negligibly (less than 1%) to the CCCS for $^{18}$O in the investigated energy range. Further investigations of $^{18}$O, $^{59}$Co, $^{112}$Sn, $^{154}$Sm, and $^{197}$Au on C, silver (Ag), and Pb targets at energies of 300 and 900 MeV/nucleon, indicate that the EM contribution to the CCCS on Ag and Pb targets increases with both the mass of the projectile and incident energy. For example, the EM contribution for $^{197}$Au on Pb target at 300 and 900 MeV/nucleon is 6.7% and 10.5%, respectively. In contrast, the EM remains negligible for all projectiles interacting with C target. These findings provide valuable insights into the mechanisms underlying high-energy interactions in nuclear physics, contributing to a deeper understanding of galactic cosmic ray propagation and offering potential applications in medical physics and space science.

Speaker: jinrong liu (beihang university)

Presentation_ID346_Liu.pdf

93 Deformation effects on a double-folding optical potential

The nuclear optical model simplifies the complex many-body problem of nuclear scattering by reducing it to a single-particle scattering problem with a complex effective central potential. It has been widely used to describe the scattering of a nuclear particle by a nucleus. With the advancement of rare isotope beam facilities, it is feasible to use exotic deformed nuclei as projectiles. In this study, we investigate the impact of nuclear deformation on double-folding optical potentials. The nucleon density profiles of the projectile and target nuclei are calculated using two modern nuclear mass models that differ primarily in their treatment of deformation. The first model is the relativistic continuum Hartree-Bogoliubov (RCHB) theory, which assumes spherical symmetry, while the second is the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), which incorporates axial symmetry. We examine several sodium (Na) isotopes to investigate how nuclear deformation affects the optical potentials. We observe that as the orientation angle of the deformed isotope decreases, the optical potential becomes deeper. Next, we consider the elastic scattering of protons on Na to explore how nuclear deformation influences the corresponding differential cross section. We find that the position of the dip in the differential cross section shifts with changes in the orientation angle.

Speaker: Myunghee Park (Ewha Womans University)

INPC2025_MyungheePark.pdf

Parallel Session: 2_Nuclear Reactions (2)

Convener: Caterina Ciampi (GANIL)

94 Single-Neutron Strength Outside Doubly Magic 132Sn

The single-neutron strengths and energies of the $1f_{7/2}$, $2p_{3/2}$, $2p_{1/2}$, $0h_{9/2}$, $1f_{5/2}$, and $0i_{13/2}$ valence neutron orbitals outside of doubly magic 132Sn have been determined via the $^{132}$Sn($d$,$p$)$^{133}$Sn reaction at 7.65 MeV per nucleon. The measurement, carried out at CERN’s HIE-ISOLDE facility using the ISOLDE Solenoidal Spectrometer, expands upon the pioneering measurement of Jones et al. [Nature 465, 454 (2010)]. The results suggest that the single-neutron strength for each orbital is carried in a single excitation, affirming the notion that $^{132}$Sn, the heaviest short-lived doubly magic nucleus, exhibits one of the strongest shell closures of all nuclei.

Speaker: Benjamin Kay (Argonne National Laboratory)

Presentation_ID642_Kay.pdf

95 Recent Developments of the MRTOF-MS at RIBF

Precise nuclear mass data is fundamental to the study of nuclear structure and provides important inputs for nucleosynthesis calculations. Low production yields and short half-lives of increasingly exotic nuclei have propelled the development of the multi-reflection time-of-flight mass spectrograph (MRTOF-MS) to become a leading method for high precision mass measurement. By reflecting low energy ions several hundred times between a pair of electrostatic mirrors, the MRTOF-MS produces an extremely long effective travel path. The MRTOF-MS is able to achieve a mass resolving power of m/Δm = 10^6 with flight times in the range of milliseconds [1], which makes it an attractive candidate for measurements of short-lived nuclei and their isomers. Indeed, the MRTOF-MS has been used as isobar separators and mass spectrometers [2–4] with many more being constructed at accelerator facilities. The stable high-voltage operation of the MRTOF-MS has been a crucial factor in its success. Currently, one of the many challenges of the MRTOF-MS is the voltage instability introduced by high frequency switching of electrodes during trapping and releasing of ions. This leads to undesirable mass dependent effects, limiting the operational range of the MRTOF-MS.
In this contribution, I will give a short overview of some developments of the MRTOF-MS at RIKEN to improve mass resolving power and operational stability, as well as a brief look at further plans for improvements in the future.

References:
[1] M. Rosenbusch, M. Wada, S. Chen, et al., Nucl. Instrum. Methods Phys. Res. Sect. Accel. Spectrometers Detect. Assoc. Equip. 1047, 167824 (2023).
[2] R. N. Wolf, F. Wienholtz, D. Atanasov, et al., Int. J. Mass Spectrom. 349–350, 123 (2013).
[3] P. Schury, M. Wada, Y. Ito, et al., Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. At. 335, 39 (2014).
[4] M. P. Reiter, S. A. S. Andrés, J. Bergmann, et al., Nucl. Instrum. Methods Phys. Res. Sect. Accel. Spectrometers Detect. Assoc. Equip. 1018, 165823 (2021).

Speaker: Jinn Ming Yap (The University of Hong Kong)

Presentation_ID729_Yap.pptx

96 Nature of single-particle states in 111Sn explored through (d,p) reaction with ISS

Shell evolution and collectivity in the tin isotopes has been examined rigorously through Coulomb excitation, where enhancements in the experimental B(E2) values in the light Sn nuclei have not yet been explained to satisfaction. To illuminate their structure and investigate nucleon-nucleon interactions, spectroscopic information on single-particle dominated states in the odd-A Sn isotopes should be measured and compared with recent shell model predictions. Spin-parity assignments and spectroscopic factors of states in light unstable Sn nuclei are limited, with no literature from (d,p) reactions.

A (d,p) transfer experiment on $^{110}$Sn was carried out at HIE-ISOLDE, CERN. The radioactive $^{110}$Sn beam was produced from proton spallation reactions on a LaCx target, and was post-accelerated to 8 MeV per nucleon. The (d,p) reaction in inverse kinematics was induced on a thin CD2 target. The outgoing protons were detected by the ISOLDE Solenoidal Spectrometer (ISS), where the energy resolution of outgoing protons was improved through the use of an external solenoidal magnetic field at 2.5 T. The beam intensity was monitored with an elastic luminosity (ELUM) detector for scattered deuterons in the target.

Multiple excited states in $^{111}$Sn were observed, and preliminary values of the (d,p) differential cross sections will be presented.

Speaker: Joochun (Jason) Park (CENS, IBS)

is686_110Sn_inpc2025.pdf

97 Fast neutron induced reactions on carbon with a diamond detector at LANSCE

The Modular Neutron Array (MoNA) Collaboration primarily studies neutron-rich nuclei near the neutron drip line with a large area neutron detector array of plastic scintillators. Fast neutrons up to 200 MeV will be produced from the decay of these unbound systems during experiments conducted at the Facility for Rare Isotope Beams (FRIB). Using the four momenta of the decay products, the reconstructed decay energies are analyzed and interpreted by comparisons to detailed Monte Carlo simulations. To simulate the neutron interactions within the plastic scintillators, cross sections are needed for reactions on hydrogen and carbon. Currently, there are missing or sparse data in the energy range of interest for many relevant reactions on carbon. The MoNA collaboration performed a dedicated experiment to measure cross sections of these reactions at the Los Alamos Neutron Science Center (LANSCE), where a white neutron beam is produced with energies up to 800 MeV. Two diamond detectors were installed on the 15L flight path 90 m away from the spallation target at LANSCE and used as both targets and detectors. A wall of MoNA detectors were set up 2 m downstream to detect the scattered neutrons. Results of various inelastic n+$^{12}$C reaction cross sections and scattered neutron angular distributions will be presented.

*This work supported by the US National Science Foundation Awards PHY-2311125, 2311126, 2011265, 2012040 and 2310078.

Speaker: Anthony Kuchera (Davidson College)

Presentation_ID173_Kuchera.pdf

98 A structure-informed approach to analyzing scattering information

Analyses of low-energy elastic scattering cross-section data usually involve fitting the data with phenomenological models, such as R-matrix theory [1]. This popular technique allows for the modelling of resonances in the (A+1) compound nucleus in the scattering region from which resonance parameters such as centroids and widths are obtained.

A limitation of this approach is that the energy centroid and widths depend upon ‘channel radius’ parameters, which divide where wavefunctions have long-range asymptotic form, and in internal region where the system is confined, and thus in resonance. These parameters are arbitrary, and not guided by nuclear structure information.

Alternatives that obtain scattering observables from the underlying nuclear physics of colliding nuclei are thus highly desirable. One such approach is the multi-channel algebraic scattering (MCAS) method [2]. MCAS uses scattering potentials derived from structure models that account for the collective and microscopic considerations that give rise to resonances. The approach optimizes scattering potential strengths to obtain centroids of resonances and bound states only, with other observables such as widths and cross sections generated automatically. Because MCAS results stem from nuclear structure considerations, it is a predictive method, with MCAS results preceded experimental discovery [3].

This talk will detail recent progress in applying MCAS to light-mass nuclear systems.

[1] P. Descouvemont and D. Baye, Rep. Prog. Phys. 73, 036301 (2010).
[2] S. Karataglidis, K. Amos, P. R. Fraser, and L. Canton, A New Development at the Intersection of Nuclear Structure and Reaction Theory (Springer, 2019), ISBN 978-3-030-21069-4.
[3] P. R. Fraser, K. Amos, L. Canton, S. Karataglidis, D. van der Knijff, and J. P. Svenne, Phys. Rev. C100, 024609 (2019).

Speaker: Paul Fraser (University of New South Wales)

Presentation_ID185_Fraser.pdf

Parallel Session: 2_Nuclear Structure (1)

Convener: Marc Verriere (Lawrence Livermore National Laboratory)

99 NUCLEAR STRUCTURE FOR ELECTROWEAK PROCESSES

Atomic nuclei are central to electroweak processes, driving the synthesis of chemical elements, serving as laboratories for testing fundamental interactions, and offering critical insights into the Standard Model of particle physics. Advances in many-body theory and high-performance computing now enable unified calculations of nuclear structure and reactions for increasingly complex systems, along with robust estimates of theoretical uncertainties. In this talk, I will highlight recent breakthroughs in ab initio approaches, showcasing their role in addressing contemporary challenges such as neutron skins in nuclei, giant dipole resonances, and lepton-nucleus cross sections.

Speaker: Sonia Bacca (Johannes Gutenberg-Universität Mainz)

NUCLEAR_STRUCTURE_FOR_ELECTROWEAK_PROCESSES_ID526_Bacca.pdf

100 Recent advances in ab initio calculaitons of electromagnetic observables

A reliable prediction of electroweak processes involving a nucleus is required to further understand nuclear structure and other related topics, such as nucleosynthesis and particle physics. In the past two decades, the range of applicability of nuclear ab initio calculations has been rapidly extending and reaching mass number of 200 systems. With controlled uncertainty estimations, an ab initio framework can provide a meaningful prediction where performing experiments is difficult or impossible. Nuclear radii and moments are complementary information to the energies and can be useful tools to test the quality of the calculations. In this presentation, I will discuss our recent results for charge radii, magnetic and quadrupole moments of medium-heavy nuclei computed with the combination of chiral effective-field theory and valence-space in-medium similarity renormalization group approach.

Speaker: Takayuki Miyagi (University of Tsukuba)

Presentation_ID355_Miyagi.pdf

101 Exotic Three-Body Decay in Open Quantum Systems

Exotic decay beyond the nuclear dripline represents a frontier in understanding the nuclear landscape. Among these phenomena, two-proton (2$p$) radioactivity emerges as a distinctive three-body process, involving the simultaneous emission of two protons from the ground state of even-Z, neutron-deficient nuclei. Recent advancements in measuring proton-proton correlations have reignited interest in this area, highlighting the interplay between structure and reaction dynamics in nuclear open quantum systems. As a complementary process, two-neutron (2$n$) emission―recently observed in certain neutron-rich dripline nuclei―has similarly garnered attention. Comparing these two exotic processes offers valuable insights into the interplay between Coulomb and nuclear interactions in the presence of a low-lying continuum. Our study employs the Gamow coupled-channel method alongside a time-dependent approach, revealing how the structure of the initial wave function, shaped by both initial-state and final-state interactions, crucially influences decay dynamics [1] and proton-proton correlations [2]. Additionally, by analyzing the energy dependence of these correlations, we uncover unique insights into non-exponential decay mechanisms [3], deepening our understanding of open quantum system properties.

[1] S. M. Wang and W. Nazarewicz, Phys. Rev. Lett. 126 (2021) 142501.
[2] S. M. Wang, W. Nazarewicz, R. J. Charity, and L. G. Sobotka, J. Phys. G 49, (2022) 10LT02.
[3] S. M. Wang, W. Nazarewicz, A. Volya, and Y. G. Ma, Phys. Rev. Research 5, 023183 (2023).

Speaker: Simin Wang (Fudan University)

Presentation_ID338_Wang.pdf

102 Results in SS-HORSE-NCSM method for multineutron systems

The study of nuclear systems consisting only of neutrons is an actual problem in nuclear physics. Interest to such systems increased after experimental works [1, 2] and theoretical calculations based on realistic nucleon-nucleon interactions (see for example [3, 4]), which declared the existence of a resonant state in a system of four neutrons (tetraneutron).

I present current progress in description of resonances in multineutron systems that have been obtained with SS-HORSE method [5] in combination with the ab initio No-Core Shell Model (NCSM) [6] with various realistic nucleon-nucleon interactions.

SS-HORSE-NCSM’s predictions for tetraneutron and trinuetron resonances have been published in [3, 7, 8].

[1] K. Kisamori et al., Phys. Rev. Lett. 116, 052501 (2016).
[2] M. Duer et al., Nature 606, 678 (2022).
[3] A. M. Shirokov et al., Phys. Rev. Lett. 117, 182502 (2016).
[4] J. G. Li et al., Phys. Rev. C 100, 054313 (2019).
[5] A. M. Shirokov et al., Phys. Rev. C 94, 064320 (2016).
[6] B. R. Barrett, P. Navrátil, J. P. Vary, Prog. Part. Nucl. Phys. 69, 131 (2013).
[7] A. M. Shirokov et al., AIP Conference Proceedings 2038, 020038 (2018).
[8] I. A. Mazur et al., Phys. Rev. C 110, 014004 (2024).

Speaker: Igor Mazur (Center for Exotic Nuclear Studies, Institute for Basic Science)

Presentation_ID296_Mazur.pptx

103 Quadrupole dynamics of carbon isotopes and 10Be

Mn/Mp, the ratio of neutron to proton quadrupole transition matrix elements has been successfully measured in recent experiments. We perform for the first time a systematic theoretical study of Mn/Mp with the ab initio no-core shell model (NCSM) for five carbon isotopes and 10Be. We find a good agreement with the available experimental data.
Using the ab initio NCSM, we also calculate Qn, the neutron quadrupole moment, and MnQp/MpQn, the ratio of Mn/Mp over the ratio of neutron to proton quadrupole moments Qn/Qp, showing good convergence. Qn can be extracted from the combination of our well-converged MnQp/MpQn results and experimental data for Mn/Mp and Qp. Although Qn itself is not directly accessible experimentally, its studies are interesting and significant since it plays a crucial role in the neutron-proton asymmetry in quadrupole deformation.

Speaker: He Li (Institute of Modern Physics, Chinese Academy of Sciences)

Presentation_ID150_Li.pdf

Parallel Session: 2_Nuclear Structure (2)

Convener: Alahari Navin (GANIL, France)

104 Spectroscopy of rare isotopes with the Active Target Time Projection Chamber

The Active Target Time Projection Chamber (AT-TPC) has been used in experiments aimed at the exploration of structural effects in radioactive nuclei using one step reactions such as transfer or elastic and inelastic scattering. When used as a solenoidal spectrometer by placing it inside a magnetic field, the AT-TPC allows to perform this type of measurement in inverse kinematics with much reduced beam intensities, down to 100 particles per second, while preserving a good resolution and a wide range of angular coverage. This presentation will showcase the performance of this detector, based on recent results obtained on nuclei in the beryllium to carbon region using pure proton, deuterium and alpha targets. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02- 06CH11357. This research used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility and used resources of the Facility for Rare Isotope Beams (FRIB) Operations, which is a DOE Office of Science User Facility under Award Number DE-SC0023633.

Speaker: Daniel Bazin (Michigan State University)

Presentation_ID275_Bazin.pdf

105 Charged particle spectroscopy with an optical time-projection chamber

Studies of rare decay channels require special instrumentation providing high efficiency and sensitivity. An example of such an approach is the Optical Time Projection Chamber (OTPC) developed at the University of Warsaw. It was designed to study two-proton radioactivity (2p), but it proved to be an excellent tool for studies of other decay channels accompanied by the emission of charged particles. Among important results obtained with the help of the OTPC, in addition to 2p spectroscopy [1,2], are the first observation of the $\beta$-delayed three-proton emission in four nuclei [3,4,5,6], a study of 6He decay into the $\alpha + d$ continuum [7], and a study of $\beta$-delayed charged particle emission in the decay of 11Be [8].

In the talk, I will present the experimental technique based on the OTPC detector and illustrate it with a selection of results obtained with the help of it, focusing on the most recent achievements.

References
[1] K. Miernik et al., Phys. Rev. Lett. 99 (2007) 192501.
[2] M. Pomorski et al., Phys. Rev. C 90 (2014) 014311.
[3] K. Miernik et al., Phys. Rev. C 76 (2007) 041304(R).
[4] M. Pomorski et al., Phys. Rev. C 83 (2011) 014306.
[5] A.A. Lis et al., Phys. Rev. C 91 (2015) 064309.
[6] A.A. Ciemny et al., Phys. Rev. C 106 (2022) 014317
[7] M. Pfützner et al., Phys. Rev. C 92 (2015) 014316.
[8] N. Sokołowska et al., Phys. Rev. C (2024) 034328.

Speaker: Marek Pfutzner (University of Warsaw)

Presentation_ID145_Pfutzner.pdf

106 Insights into the structure and decay channels of ^{4}He using NFS neutron beam and ACTAR TPC apparatus.

Until recently, the transition of 4He from its ground state to the 0+ first excited state was commonly interpreted as a monopole excitation or "breathing mode" [1]. This mode involves symmetric expansion and contraction of the nucleus, akin to a balloon inflating and deflating, while preserving its spherical shape.

Recent calculations using the No Core Gamow Shell Model (NCGSM), which treats the 4He nucleus as an open quantum system, challenge this previous view. By incorporating multiple reaction channels, such as [1H + 3H], [3He + n], and [2H + 2H], the NCGSM provides a more accurate solution to the N-body problem and predicts the excitation function for 4He decay across these channels.

To explore these predictions, we first analyzed correlation functions for the [1H + 3H] and [2H + 2H] channels from Ni+Ni reactions at incident energies of 32 and 52 MeV/A using the FAZIA+INDRA apparatus. Our study highlights the limitations of the apparatus as well as limitations of correlation function methods. These finding will be presented.

In addition, we propose an alternative experimental approach to extract the branching ratios of 4He decay channels as a function of excitation energy. This approach involves a 4He(n,n') experiment using the NFS neutron beam in combination with the ACTAR TPC, filled with pure 4He gas. This method aims to track the evolution of the weight of each decay channel as a function of excitation energy, providing critical constraints on theoretical calculations.

These studies offer new insights into the structure and decay mechanisms of 4He, opening pathways to refine our understanding of light nuclei as open quantum systems.

References:

[1] S. Kegel et al., Measurement of the alpha particle monopole transition form factor challenges theory: A low energy puzzle for nuclear forces, Phys. Rev. Lett., 130, 152502 (2023).
[2] N. Michel, W. Nazarewicz. and M. Ploszajczak, Description of the Proton-Decaying 0+2 Resonance of the alpha Particle, Phys. Rev. Lett., 131, 242502 (2023); 133, 239901 (2024).

Speaker: Abdelouahad Chbihi (GANIL)

AlphaDecay_INPC25_AChbihi.pdf

107 Search for gamma decay of near-threshold states in light nuclei

We present recent results on the $\gamma$ decay of peculiar near-threshold states in $^{11}$B and $^{14}$C [1,2], located in the continuum just above the proton- and neutron-decay threshold, respectively. Near-threshold states play a major role to understand the onset of collectivization and clusterization phenomena, as well as the coupling between bound and scattering states, and they have impacts on the abundance of elements in the Universe. These resonances can be described by the Shell Model Embedded in the Continuum (SMEC), which points to the appearance of near-threshold states in light nuclei as a universal phenomenon [3]. In this context, we have performed two experiments, at LNL with the GALILEO-TRACE and at ANL with the GRETINA-ORRUBA setups, using fusion-evaporation reactions to populate near-threshold resonances in $^{11}$B and $^{14}$C, respectively. For these nuclei, SMEC calculations predict $\gamma$-ray branches of the order of 10$^{-3}$ and 10$^{-5}$, respectively and, for the first time, limits were established in the present experiments. Implications for the description of $^{11}$B and $^{14}$C as open quantum systems will be discussed and future perspectives will be presented.

[1] S. Bottoni et al, Phys. Lett. B 855, 138851 (2024)
[2] G. Corbari et al, in preparation
[3] J. Okołowicz, et al. Phys. Rev. Lett. 124, 042502 (2020)

Speaker: Simone Bottoni (Università degli Studi di Milano and INFN)

Bottoni_INPC25.pdf

108 Fragmentation features of Be, B, C nuclei in nuclear track emulsions

Starting with the discovery of the nuclear component of cosmic rays, the nuclear track emulsion method (NTE) makes an opportunity to study the composition of the relativistic fragmentation of nuclei at high-energy accelerators. The promising potential of the relativistic approach to the analysis of ensembles of fragments was manifested in NTE exposed by nuclei at several GeV per nucleon accelerated at the JINR Synchrophasotron and Bevalac (USA) in the 1970s. Since the 2000s of the NTE method is applied in the BECQUEREL experiment at the JINR Nuclotron in respect to the cluster structure of nuclei, including radioactive ones, as well as the search for unstable nuclear-molecular states. Nucleon associations (clusters) are one of the basic phenomena in atomic nuclei structure. Their simplest observable manifestations are the lightest He and H nuclei. Superpositions of the lightest clusters and nucleons form subsequent nuclei (including unstable$^8$Be and B), which act as constituent clusters themselves for more complicated nuclear systems. The phenomena of cluster dissociations of light Be and B isotopes are discussed. Charge topology and angular spectra of fragmentation of 1.2 A GeV $^7$Be nuclei in NTE are presented. The dissociation channels $^4$He +$^3$He, 2$^3$He+ n, $^4$He + 2$^1$H are considered in detail. It is established that the events $^6$Be + n amount about to 27% in the channel $^4$He + 2$^1$H. The experimental results are compared with model data of fragmentation of such nuclei in NTE. The next topic consisted in the study of unstable states of $^9$Be and $^9$B. The experimental data for this nuclei obtained in relativistic fragmentation of carbon ($^{10}$C) and beryllium (from $^{10}$B) fragmentation in NTE. The opportunity of searching with nuclear track emulsions for more complex excitations in light nuclei - isobar-analogue states for $^9$Be and $^9$B isotopes are discussed [1-3].
References
[1] P. I. Zarubin Lecture Notes in Physics, Vol. 875, Clusters in Nuclei,
Volume 3. Springer Int. Publ., 51 (2013) [arXiv:1309.4881].
[2] D. A. Artemenkov et al., 8Be and 9B nuclei in dissociation of
relativistic 10C and 11C nuclei, EPJ Web of Conferences DOI: 10.1051/ conf/201611 0602.
[3] P. I. Zarubin et. al., Prospects of Searches for Unstable States
in Relativistic Fragmentation of Nuclei, Physics of Atomic Nuclei, 2022, Vol. 85, No. 6, pp. 528–539.

Speaker: Denis Artemenkov (JINR)

109 Study of the full electric dipole strength of the double halo nucleus 11Li using proton inelastic scattering

Over the years there have been many efforts put in trying to understand the electric dipole (E1) strength of atomic nuclei. It is known that the nuclear E1 response is mostly dominated by the IsoVector electric Giant Dipole Resonance (IVGDR), which can be understood as a collective harmonic motion of protons against neutrons [1].

In neutron rich-nuclei, part of the E1 strength is redistributed around the neutron separation energy, producing a concentration of low energy dipole excitations known as a Pygmy Dipole Resonance (PDR), which instead consists in an oscillation of a neutron skin against an isospin symmetric core. The closer we are to the neutron drip-line, the more complex the PDR becomes, heavily affecting its properties [2].

This study focuses in the double neutron halo nuclei 11Li. The PDR in 11Li is significantly different from a regular PDR due to the very low neutron separation energy of 11Li, which produces a large imbalance of neutrons in the neutron skin with pairing energy playing an important role in it. Although the PDR for 11Li was initially observed in [3], this observation only accounts for a small part of the total E1 response in 11Li. Recent theoretical studies have predicted the presence of an IVGDR in 11Li that was not observed before, which accounts for most of its E1 strength [4].

In order to experimentally study the complete E1 stregnth of 11Li, an inelastic scattering experiment in inverse kinematics was performed at the Facility for Rare Isotope Beams (FRIB) in July 2024. A 53.4 MeV/u 11Li beam was sent into the Active Target Time Projection Chamber (AT-TPC) [5] which acted as the proton active target, as well as the tracking detector for the scattered protons from the reaction. Additionally, the S800 spectrometer [6] was used at the end of the beam line in order to study the decay products of the excited 11Li.

Although the PDR in 11Li was already observed previously [3, 7, 8], the results from this experiment provide a preliminary measurement of an IVGDR in 11Li, which to our knowledge is a first for double halo nuclei. These results are of importance to fully understand the E1 response of 11Li, and may provide useful insight into the E1 properties of halo nuclei in general.

References:
[1] M. N. Harakeh and A. van der Woude. Giant Resonances: Fundamental High-frequency Modes of Nuclear Excitation. Oxford science publications. Oxford University Press, 2001.
[2] T. Aumann. Low-energy dipole response of exotic nuclei. Eur. Phys. J. A, 55:234, 2019.
[3] T. Nakamura, et al. Observation of strong low-lying E1 strength in the two-neutron halo nucleus 11Li. Phys. Rev. Lett., 96:252502, Jun 2006.
[4] R. A. Broglia et al. Pygmy resonances: what’s in a name? Physica Scripta, 94(11):114002, 2019.
[5] J. Bradt et al. Commissioning of the Active-Target Time Projection Chamber. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 875, Pages 65-79, 2017.
[6] D. Bazin et al. The S800 spectrograph. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 204, Pages 629-633, 2003.
[7] R. Kanungo et al. Evidence of soft dipole resonance in 11Li with isoscalar character. Phys. Rev. Lett., 114:192502, May 2015.
[8] J. Tanaka et al. Halo-induced large enhancement of soft dipole excitation of 11Li observed via proton inelastic scattering. Physics Letters B, 774:268–272, 2017.

Speaker: Jose Manuel López González (University of Santiago de Compostela)

Presentation_ID395_LopezGonzalez.pdf

110 Study on the shell structure of 11C with alpha scattering by using MATE

The nuclear shell structure provides an important guide for our understanding of the nuclear structure and the underlying nuclear forces. Following a series of studies on the weakly-bound nuclear region far away from the stability line, many exotic phenomena have been found, such as the emergence of new magic numbers. The study of new magic numbers can provide us with a good perspective on understanding the evolution of the
nuclear shell structure. Recently, the existence of the new proton magic number Z = 6 was found in the neutron-rich carbon isotopes, which raised the question of whether the Z = 6 magic number persists in the neutron-deficient carbon isotopes. At present, there exist only the experimental results of 10C on the neutron-deficient side, which shows greater neutron contribution to E2 transition than that of protons. To further investigate the neutron-deficient carbon isotopes, we carried out an alpha inelastic scattering experiment to study the structure of 11C.

The a(11C, a') experiment was carried out at the RIBLL1, HIRFL. A primary beam of 12C bombarded a beryllium target to produce a 55-MeV/u secondary beam of 11C. The 11C beam was incident on an active target Time Projection Chamber (TPC) named MATE (Multi-purpose Active target Time projection chamber for nuclear astrophysical and exotic beam Experiments). MATE is a new detector developed at IMP in recent years and is mainly composed of TPC and silicon detectors. By measuring the yield of the recoil alpha particles, a differential cross-section can be obtained. The ratio of the neutron and proton contribution to the excitation Mn/Mp will be obtained from reaction theory analysis, combining the results from this work and earlier (p,p') measurement. The results will shed light on the important question of whether or not there exists a proton subshell closure in 11C.

Speaker: Zhichao ZHANG (Institute of Modern Physics, Chinese Academy of of Sciences)

Presentation_ID524_Zhang.pdf

Parallel Session: 2_Nuclear Structure (4)

Convener: Kyo Tsukada (ICR Kyoto University)

111 Probing multiple shape coexistence in Cd isotopes using Coulomb excitation

Mid-shell Cd nuclei were traditionally considered to be the best examples of vibrational nuclei. Recent studies that combined detailed γ-ray spectroscopy with sophisticated beyond-mean-field calculations had suggested [1,2] that the low-lying 0$^+$ states in $^{110,112}$Cd possessed prolate, triaxial, and oblate shapes with rotational-like bands built upon them. If confirmed, this would have major implications on structural interpretations of nuclei in the Z = 50 region, and perhaps beyond. Soon afterwards a similar picture was suggested for $^{106}$Cd [3,4].

The low-energy Coulomb-excitation technique represents an ideal tool to study nuclear deformation. It enables a direct determination of electromagnetic transition matrix elements between low-lying excited states including spectroscopic quadrupole moments and signs. Those can be further analysed in terms of quadrupole invariants [5] yielding model-independent information on shape parameters of individual states. This requires, however, extensive sets of high-precision experimental data.

A multi-faceted experimental program to ascertain the deformation of low-energy states in $^{110}$Cd has been initiated. We seek to firmly establish the shape of the 0$^+_{1,2,3}$ states through the use of the rotation-invariant sum rules for $E$2 transitions. Coulomb-excitation measurements were performed using various reaction partners: $^{14}$N and $^{32}$S beams with EAGLE at HIL UW (Warsaw, Poland), $^{60}$Ni beam with AGATA at LNL (Legnaro, Italy) and $^{110}$Cd beam on a $^{208}$Pb target with GRETINA at ANL (Argonne , USA). These measurements have been complemented by an experiment performed at TRIUMF-ISAC with the GRIFFIN spectrometer examining the decays of $^{110}$Ag/$^{110}$In that will provide high-precision data on $\gamma$-ray branching ratios and transition mixing ratios. First results on quadrupole deformation parameters for the 0$^+_1$ and 0$^+_2$ states, demonstrating non-axial character of the ground state in $^{110}$Cd, will be presented. These experimental findings will be discussed in the context of: (i) Symmetry-Conserving Configuration-Mixing approach [1,2] and, (ii) new calculations with the general quadrupole collective Bohr Hamiltonian model involving two variants of interactions: SLy4 and UNEDF0.

Future perspectives will be outlined, including a brief overview of Coulomb-excitation studies addressing shape coexistence in the Z ∼ 40 – 50 mass region within the experimental campaigns at HIL Warsaw and at LNL Legnaro.

References
[1] P. Garrett et al., Phys. Rev. Lett. 123 (2019) 142502.
[2] P. Garrett et al., Phys. Rev. C 101 (2020) 044302.
[3] M. Siciliano et al., Phys. Rev. C 104 (2021) 034320.
[4] D. Kalaydjieva , PhD thesis, Universite Paris-Saclay, 2023
[5] K. Kumar et al., Phys. Rev. Lett. 28 (1972) 249

Speaker: Katarzyna Wrzosek-Lipska (Heavy Ion Laboratory, University of Warsaw)

Presentation_ID582_Wrzosek-Lipska_pdf-wp.pdf

112 Approaching $^{100}$Sn: Lifetime Measurements of Low-Lying States in $^{102}$Sn

The nuclear structure of doubly magic nuclei, such as $^{100}$Sn and its neighboring isotopes, has attracted significant attention from both experimental and theoretical perspectives. This interest stems from the unique insights these nuclei offer for testing the nuclear shell model and their relevance to the astrophysical rapid-proton capture process [1].

While the region near $^{100}$Sn is challenging to access experimentally, lifetime measurements of the first excited states in nearby nuclei, such as $^{102,103}$Sn, are crucial for quantifying the evolution of nuclear shell structure and assessing the balance between pairing and quadrupole correlations [2].

In this contribution, we present recent results on lifetime measurements in $^{102}$Sn. The experiment was conducted in May 2021 as part of the FAIR phase-0 campaign at GSI, utilizing the DEcay SPECstroscopy setup [3]. Nuclei of interest were produced via fragmentation reactions of a $^{124}$Xe beam on a $^{9}$Be target and subsequently identified using the FRS separator. The Sn isotopes were stopped in the AIDA array, with decaying gamma rays collected by the FATIMA array. This setup allowed for direct lifetime measurements with precision up to a few tens of picoseconds.

We will discuss our findings and their potential interpretation in terms of seniority symmetry conservation and core-breaking effects. These results provide valuable insights into the nuclear structure near $^{100}$Sn and contribute to our understanding of shell evolution in exotic nuclei.

[1] T. Faestermann, M. Górska, H. Grawe, Prog. Part. Nucl. Phys. 69 (2013) 85.
[2] M. Siciliano et al., Phys. Lett. B 806, 135474 (2020).
[3] A.K. Mistry et al., Nucl. Instr. Meth. A 1033 (2022) 166662.

Speaker: Daniele Mengoni (University and INFN, Padova)

Presentation_ID076_Mengoni.pdf

113 Nuclear deformation in fission fragments studied with novel implementations of Doppler shift lifetime measurement techniques

The experimental investigation of the structure of atomic nuclei reveals the presence of different shapes as, for example, spherical or ellipsoidal. The latter can have sizable deviation (i.e., deformation) with respect to the spherical shape. Nuclear deformation is found especially far from the magic numbers of nuclear stability. The evolution of nuclear shapes in different regions of the nuclear chart is the subject of extensive studies, by means of different experimental [1,2] and theoretical techniques [2,3].
Recent experimental results on the deformation of neutron-rich nuclei with mass A$\approx$100 at medium-high spin (8-10$\hbar$) will be presented. Those follow the measurement of the lifetimes of excited states to determine transition strengths, from which the magnitude of the deformation can be inferred. Particular focus will be on a novel implementation of the Doppler Shift Attenuation Method (DSAM) for the measurement of lifetimes of excited states in fission fragments. This method has been applied to the first set of data taken with an active fission target coupled to an array of germanium detectors [4]. The nuclei have been populated via neutron-induced fission on $^{235}$U, dissolved in a liquid scintillator (fission tag via active target). This reaction, combined with a high-resolution gamma detection system, has allowed for high-statistics studies, complementary to the those performed, for example, at radioactive ion beam facilities. Thermal neutrons have been delivered by the ILL (Institut Laue-Langevin) nuclear reactor and the FIPPS (FIssion Product Prompt gamma-ray Spectrometer) instrument has been used for gamma-ray detection [5]. The active target has allowed to “tag” the fission events, suppressing the gamma rays produced via the beta decay of the fission fragments. The experimental data have been compared to simulations obtained using a Geant4 Monte Carlo code developed for FIPPS. Different event generators, particularly the one for fission fragments, based on the FIFRELIN database [6], have been included in the simulation code, as well as the full geometry of the detection system and the gamma decay through complete level schemes. New results have been obtained for the lifetimes of excited states in $^{97,101}$Zr and $^{100,102}$Nb nuclei, together with the re-evaluated values for $^{99,100,101,102}$Zr. These have been compared with the previously reported measurements in the literature [7,8], via an accurate evaluation of all the systematic errors. The comparison of the new results with recent theoretical calculations will be shown. A development of a plunger device for lifetime measurements in neutron-induced fission experiments will be also presented in the final perspectives.

References:
[1] P.E. Garrett, M. Zielińska and E. Clément, Prog. Part. and Nucl. Phys. 116, 103931 (2022).
[2] S. Leoni, B. Fornal, A. Bracco., Y. Tsunoda, T. Otsuka, Prog. Part. Nucl. Phys. 139 (2024) 104119
[3] T. Otsuka, A. Gade, O. Sorlin, T. Suzuki, Y. Utsuno, Rev. Mod. Phys. 92, 015002 (2020).
[4] F. Kandzia et al., Eur. Phys. J. A 56, 207 (2020).
[5] C. Michelagnoli et al., Eur. Phys. J. Web Conf. 193, 04009 (2018).
[6] O. Litaize, O. Serot, and L. Berge, Eur. Phys. J. A 51, 177 (2015).
[7] A. G. Smith et al., Phys. Rev. C 86, 014321 (2012).
[8] G. Pasqualato et al., Eur. Phys. J. A 59, 276 (2023).

Speaker: Giacomo Colombi (University of Guelph)

Presentation_ID166_Colombi.pdf

114 Exploring triaxiality in neutron-rich 112,114Mo isotopes using beta-delayed gamma-ray spectroscopy at RIKEN RIBF

The gamma band of even-even deformed nuclei has traditionally been interpreted as a vibrational band related to the triaxial vibration of an axially symmetric deformed shape. However, recent theoretical studies suggest that typical gamma bands can be interpreted as a triaxial rotor with a weakly triaxial shape [1]. Neutron-rich Mo isotopes provide an excellent opportunity to explore triaxiality, as their low-lying second 2$^+$ states are comparable in energy to the first 4$^+$ state and can be interpreted using various models, including the rigid-triaxial rotor, gamma-unstable nuclei, and gamma vibration [2]. In this case, not only the band head of the gamma band but also the energies of the band members are important to distinguish between several pictures.
In the present study, we investigated the deformation evolution of neutron-rich Mo isotopes with mass numbers 112 and 114 using $\beta$-delayed $\gamma$-ray spectroscopy at RIKEN RIBF using the Ge cluster EURICA and fast timing array FATIMA. The level scheme of $^{112}$Mo was constructed from the gamma-gamma coincidences and energy matching information. The lifetime of the first 2$^{+}$ state in $^{112}$Mo was measured. Our results reveal a gradual decrease in quadrupole deformation as a function of mass number. The gamma band with K$^\pi$ = 2$^+$ and the K$^\pi$ = 4$^+$ state were observed in $^{112}$Mo. A very small odd-even energy staggering observed in the gamma band indicates an axially symmetric rotation of the band head, which is not reproduced by the five-dimensional collective Hamiltonian calculation using the SLy5+T interaction.
In this conference, we will present the experimental and theoretical results, including a discussion on our attempts to reproduce the gamma band by changing the effective interaction. We will also discuss an indication for the modification of the pairing strength in neutron-rich Mo isotopes.

[1] T. Otsuka, Y. Tsunoda, Y. Utsuno, et al., arXiv preprint arXiv:2303.11299 (2023).
[2] J. Ha, T. Sumikama, F. Browne, et al., Phys. Rev. C 101, 044311 (2020).

Speaker: Dr Toshiyuki Sumikama (RIKEN Nishina Center)

Presentation_ID198_Sumikama.pdf

115 Triaxiality of neutron-rich ruthenium nuclei studied by lifetime measurements

Neutron-rich ruthenium nuclei with mass around A≈110 are considered some of the best examples for nuclei with triaxial shape in their ground state. Quantitative information about the deformation in general and the degree of triaxiality in particular was obtained from lifetime measurements of short-lived excited states in 108Ru, 110Ru, and 112Ru. Lifetimes were measured using the recoil distance Doppler shift (RDDS) technique for states in both the ground-state band and the K=2 gamma band for the Ru isotopes under study. Combining the lifetimes with known branching rations, the measurements provide a multitude of new B(E2) transition strengths. Excited states were populated in fusion-fission reactions between a 238U beam at 6.2 A MeV and a 9Be target in an experiment performed at GANIL. The fission fragments were identified in mass, charge, and atomic number in the magnetic spectrometer VAMOS on an event-by-event basis. The velocity of nuclei exiting the target foil was slowed down in a degrader that was mounted in a plunger device at variable distances from the target. The AGATA gamma-ray tracking array was used to measure picosecond lifetimes with the RDDS method. The experiment produced a wide range of neutron-rich fission fragments, for which lifetimes could be measured under identical experimental conditions. An overview of the results will be presented, with emphasis on the chain of Ru isotopes. The comparison of experimental results with the triaxial rotor model and with beyond-mean field calculations provides quantitative information on the evolution of triaxiality in the chain of Ru isotopes.

Speaker: Andreas Görgen (University of Oslo)

Presentation_ID586_Gorgen.pdf

Presentation_ID586_Gorgen.pptx

116 TROPIC: A Python Program for Calculating Reduced Transition Probabilities

Measurements of level lifetimes and the extracted transition probabilities are one of the cornerstones of nuclear structure physics. The reduced transition probabilities, B(πλ; $J_i → J_f$ ) yield information about the structure, wavefunctions, and matrix elements of excited states connected by electromagnetic transitions in a given nucleus. The techniques for measuring lifetimes have expanded and includes a range from microseconds to femtoseconds and shorter. While lifetime measurement techniques vary, the extraction of transition probabilities is the same. We have developed the TROPIC program to provide a modern and efficient way to extract transition probabilities B(πλ). TROPIC (TRansitiOn ProbabIlity Calculator) is a program for calculating B(πλ) values written in Python 3 with the NumPy and SciPy libraries. Several design decisions were implemented to provide a streamlined process for the user and mitigate drawbacks that were present in other programs. The results from TROPIC have been compared with two other programs, TRANSNUCLEAR and RULER. The answers are as expected identical, but the investment of input to output time is reduced. Details about the design decisions behind TROPIC and its features will be presented.

Speaker: Dr Kevin Lee (University of Notre Dame)

Presentation_ID554_Lee.pdf

Parallel Session: 2_Quantum Computing and Artificial Intelligence in Nuclear Physics

Convener: Dean Lee (Michigan State University)

117 Parametric Matrix Models

We present a general class of machine learning algorithms called parametric matrix models. In contrast with most existing machine learning models that imitate the biology of neurons, parametric matrix models use matrix equations that emulate physical systems. Parametric matrix models work by replacing operators in the known or supposed governing equations with trainable, parametrized ones. Similar to how physics problems are usually solved, parametric matrix models learn the governing equations that lead to the desired outputs. Parametric matrix models take the additional step of applying the principles of model order reduction and reduced basis methods to find efficient approximate matrix equations with finite dimensions and can be efficiently trained from empirical data. Such equations are guaranteed to exist and can be constructed, in theory, via methods such as the proper orthogonal decomposition.

While originally designed for scientific computing, we prove that parametric matrix models are universal function approximators that can be applied to general machine learning problems. After introducing the underlying theory, we apply parametric matrix models to a series of different challenges that show their performance for a wide range of problems. We first demonstrate the superior performance of PMMs for three scientific computing examples: multivariable regression, quantum computing, and quantum many-body systems. We then show the broad versatility and efficiency of PMMs on several supervised image classification benchmarks as well as hybrid machine learning when paired together with both trainable and pre-trained convolutional neural networks. For all the challenges tested here, parametric matrix models produce accurate results within an efficient and interpretable computational framework that allows for input feature extrapolation

Speaker: Danny Jammooa (Facility for Rare Isotope Beams)

Presentation_ID251_Jammooa.pdf

118 Quantum thermalization of Quark Gluon Plasma

Thermalization of the quark gluon plasma (QGP) created in relativistic heavy-ion collisions is a crucial theoretical question in understanding the onset of hydrodynamics, and in a broad sense, a key step to the exploration of thermalization in quantum many body systems. Addressing this problem theoretically, in a first principle manner, requires a real-time, non-perturbative method. To this end, we carry out a fully quantum simulation on a classical hardware, of a massive Schwinger model, which well mimics QCD as it shares the important properties such as confinement and chiral symmetry breaking. We focus on the real-time evolution of the Wigner function,
which is the Wigner—Weyl transformation of the gauge-invariant two-point correlation function and it serves as the quantum analogy of the quark distribution function in phase space.

Starting from a non-equilibrium initial state, the real time evolution of the Wigner functions, as well as the entanglement entropy, both demonstrate that thermalization of the quantum system is approachable. In particular, relaxation to the thermalized state depends on coupling strength, in the presence of quantum fluctuations. The system tends to thermalize in the strong-coupling case, but not the weak-coupling ones. We also study the connection of the Wigner function thermalization to the Eigenstate Thermalization (ETH). The ETH is a well-known postulation that explains the thermalization of observables in isolated quantum many-body systems without processing quantum ergodicity. The satisfaction of ETH sheds light on the rapid thermalization of QGP created in heavy-ion collisions.

We also find the weak eigenstate thermalization hypothesis corresponding to the choice of difference initial quantum state. It indicates the relationship between the thermalization behavior and discrete symmetry like parity based on the quantum many body scar states reflecting the symmetry of the quantum system.

Ref: arXiv: 2412.00662 [hep-ph]

Speakers: Prof. Li Yan (Fudan University), Shile Chen (Tsinghua University), Prof. Shuzhe Shi (Tsinghua University)

Presentation_ID493_Chen.pdf

119 Reliable deep learning for nuclear physics: addressing uncertainty quantification and extrapolation

The rise of deep learning has provided transformative tools across numerous scientific disciplines, including nuclear physics, and has attracted significant attention from researchers. However, the 'black box' nature of deep learning often raises concerns about its reliability, particularly in critical applications such as nuclear physics. The reliability of models comes not only from accurate predictions but also from well-calibrated uncertainty quantification and the ability to extrapolate beyond the available data. In this talk, we discuss these fundamental challenges in conventional deep learning and demonstrate how advanced techniques developed by recent computer science progress can effectively address them. We first introduce straightforward yet scalable and effective uncertainty quantification methods grounded in probabilistic frameworks, showcasing their application in R-matrix fitting to nuclear elastic scattering. Furthermore, we present a robust solution to overcome the inherent limitation of extrapolation by leveraging neural networks to uncover underlying mathematical expressions, highlighting its success in predicting nuclear properties across the landscape. Our work underscores that, with the right techniques, deep learning can serve as both a powerful and trustworthy tool in nuclear physics research.

Speaker: Chanhee Kim (Sungkyunkwan University)

Presentation_ID119_Kim.pdf

120 A foundation model for TPC data

This work centers on providing a multi-purpose deep learning model for time projection chamber detector systems that can be tuned for various tasks such as event identification, particle or track identification, and regression tasks. Time-projection chambers are used across various subfields of nuclear physics experiments to provide three-dimensional “images” of particle reactions or decays. Foundation models such as the GPT models, BERT, and DALL-E have shown impressive performance in text and image domains. Such models are built through large-scale training on self-supervised tasks. Similarly, we present results of using a point-cloud shuffling task to build our foundation model. To build this initial model, we used data from the $^{16}$O $+ $ $\alpha$ and $^{16}$C $+$ $d$ experiments using the Active-Target Time Projection Chamber (AT-TPC) at the Facility for Rare Isotope Beams at Michigan State University. We then tuned this model on a downstream task of counting the number of reaction products for events in the $^{22}$Mg $+ \alpha$ experiment, also using the AT-TPC at FRIB. Data from the experiment used for the downstream task was not incorporated into the pretrained foundation model. We show that we can achieve an F1 score of .91 with only 250 labeled training events using our pretrained model, compared to an F1 score of .45 using 250 labeled training events for a model trained from randomly initialized weights. Similarly, we find that more than 2000 labeled events are needed to surpass an F1 score of .9 when training a model from scratch. We discuss current efforts in incorporating more data into our pretrained model and our efforts that build towards our future plans of incorporating data from other TPCs.

This work is supported in part by NSF grants OAC-2311263, OAC-1836650, PHY-2012865 and the Davidson College RISE program.

Speaker: Prof. Michelle Kuchera (Davidson College)

Presentation_ID177_Kuchera.pdf

121 Real-Time Charged Track Reconstruction with AI in CLAS12

Charged track reconstruction is a pivotal task in nuclear physics experiments, enabling the detection and analysis of particles generated in high-energy collisions. Machine learning (ML) has proven to be a transformative tool in this domain, overcoming challenges such as intricate detector geometries, high event multiplicities, and noisy data. While traditional methods like the Kalman filter have been widely used for pattern recognition, ML approaches—including neural networks, graph neural networks (GNNs), and recurrent neural networks (RNNs)—offer enhanced accuracy and scalability.
In this presentation, we share our findings on leveraging AI to aid data reconstruction for identifying charged tracks in the Drift Chambers of the CLAS12 detector. A Convolutional Autoencoder (CNN) is employed to de-noise the drift chamber data, while a Multi-Layer Perceptron (MLP) network identifies track candidates from the segments reconstructed in each layer. This AI-driven track identification results in approximately a $60\%$ increase in statistics for multiparticle inclusive states. Additionally, we developed a neural network to predict particle parameters directly from raw Drift Chamber hits, enabling full event reconstruction at a rate of approximately 20 kHz, surpassing the experimental data acquisition speed. These advancements are redefining the application of AI in experimental physics and transforming the methodologies of nuclear physics experiments.

Speaker: Gagik Gavalian (Jefferson National Lab)

INPC-AI-CLAS12-GAVALIAN.pdf

Tuesday, 27 May

Parallel Session: 3_Hadrons in Nuclei

Convener: Byung-Geel Yu (Korea Aerospace University)

122 Hadron structures toward dense matter

Hadrons structures are discussed based on various approaches such as constituent quarks, chiral symmetry and heavy quarks, which would be important inputs when discussing dense hadronic matter. For this we show some recent results which we have learned from the study of standard and exotic hadrons. We also discuss property changes of constituent quarks and chiral symmetry breaking at finite densities.

Speaker: Atsushi Hosaka (RCNP, The University of Osaka)

2025_0525_INPC_uploaded_Hosaka-2.pptx

2025_0525_INPC_uploaded_Hosaka.pdf

123 The phi meson in dense matter from theory and experiment

The status of recent theoretical and experimental research related to the
properties of the phi meson in nuclear matter is reviewed, focusing on
observables that will be measured at the J-PARC E16 experiment, including
dilepton and K^+K^- decay modes and their angular distributions.
The relation of these observables to fundamental properties of nuclear matter,
such as chiral symmetry, its partial restauration in nuclear matter, in-medium
Lorentz and charge symmetry violation and the resultant modification of hadronic
dispersion relations, will also be discussed.

Speaker: Philipp Gubler (JAEA)

Presentation_ID147_Gubler.pptx

124 Hyperon-deuteron momentum correlation function including the effect of the deuteron breakup

Momentum correlation functions measured in heavy-ion scattering
experiments have attracted significant attention as a source of
information on the interaction between hyperons and nucleons.
The correlation functions between hyperons and deuteron have been
analyzed using theoretical expressions that approximate the deuteron
as a single particle.However, it is essential to treat the three-body
dynamics, including the relative degrees of freedom of the deuteron,
to obtain more accurate results. To this end, the three-body system
of the hyperon and deuteron is described by the Faddeev equation,
a wave function is constructed using its solution, and a correlation
function that incorporates the three-body dynamics is evaluated.
The effect of the deuteron breakup on the correlation function
between the hyperon and deuteron is then discussed.

Speaker: Michio Kohno (RCNP, Osaka University, Japan)

Presentation_ID360_kohno.pdf

125 Identifying the transverse and longitudinal modes of the $K^*$ and $K_{1}$ mesons through their angular dependent decay modes

The mass shifts of chiral partners provide crucial insights into the role of a spontaneous chiral symmetry breaking in hadron mass generation. The $K^*$ and $K_1$ mesons, with their vacuum widths under 100 MeV, are particularly well-suited for precise mass shift measurements. However, the distinct momentum dependence of the longitudinal and transverse modes can blur the peak positions. In this talk, we examine the angular dependence of the two-body decays of $K^*$ and $K_1$ mesons. Our findings reveal that the longitudinal and transverse modes of the $K^*$ can be effectively isolated by observing the pseudoscalar decay along the forward and perpendicular directions, respectively. The same goal for $K_1$ meson can be achieved by an additional measurement of a produced vector meson’s polarization.

Speaker: In Woo Park (Yonsei University)

Presentation_ID424_Park.pdf

Presentation_ID424_Park.pptx

Parallel Session: 3_Hot and Dense Nuclear Matter

Convener: Su Houng Lee (Yonsei University)

126 Comparisons and Predictions for Collisions of deformed 238U nuclei at $\sqrt{s_{NN}} = 193$ GeV

Relativistic heavy ion collisions provide exciting new ways to probe nuclear structures. In this talk, we present model-to-data comparisons for the collisions of very-deformed nuclei (U+U collisions at $\sqrt{s_{NN}} = 193$ GeV) and slightly-deformed nuclei (Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV) at RHIC. For theoretical calculations, we use a multistage model consisting of boost-invariant IP-Glasma initial state, MUSIC hydrodynamics, and a hadronic transport cascade generated by iS3D & SMASH. Two different Woods-Saxon parametrizations per U and Au are used, allowing for comparisons within our model. In doing so, we achieve a consistent description of existing bulk and flow measurements favouring more modern parameter sets. We also present our prediction for the $v_2-\< p_T \>$ correlation [arXiv:2308.09816], which were later found to match very well the experimental result by STAR [arXiv:2401.06625], thus demonstrating that momentum-flow correlations are sensitive probes of nuclear deformation. We will also report on the fitted values of the xenon deformation parameters through our (3+1)D calculations of Xe+Xe collisions at $\sqrt{s_{NN} = 5.44$ TeV.

Speaker: Sangyong Jeon (McGill University)

Presentation_ID373_Jeon.pdf

127 Constraining the nuclear equation of state from terrestrial experiments and neutron star observations using relativistic mean-field models

The accurate measurement of the neutron skin thickness of 208Pb by the PREX collaboration, using parity-violating electron scattering, has revealed a significant discrepancy between the experimental result and theoretical predictions. To explain the PREX-2 data, a large slope parameter of the nuclear symmetry energy, L, is required. However, a smaller value of L is favored to account for the compact neutron star radii indicated by the precise measurements from NICER mission. In particular, a NICER view of the fourth pulsar, PSR J1231-1411, provides the stringent constraint on a neutron star radius. To address this tension between terrestrial experiments and astrophysical observations, we construct nuclear equations of state using recently developed effective interactions within the relativistic mean-field (RMF) model, incorporating isoscalar- and isovector-meson mixing (Astrophys. J. 929 (2022) 82; Phys. Lett. B 843 (2023) 138013; arXiv:2411.13210). We investigate the effects of scalar-isovector meson and its mixing on asymmetric nuclear matter, finite nuclei, and neutron star matter, with particular focus on the density dependence of the nuclear symmetry energy. Our findings reveal that the nuclear symmetry energy softens around twice the nuclear saturation density due to scalar-meson mixing. This feature allows for a simultaneous explanation of the PREX-2 data and astrophysical observations from NICER and GW170817. Additionally, we discuss the result of the neutron skin thickness of Ca48 from the CREX experiment.

Speaker: Tsuyoshi Miyatsu (Soongsil University)

INPC2025.T.Miyatsu.pdf

INPC2025.T.Miyatsu.pdf

INPC2025.T.Miyatsu.pdf

128 Dynamical core-corona initialization in high-energy nuclear collisions

The dynamical core-corona initialization (DCCI) model [1] is a novel framework to describe the space-time evolution of both equilibrium (the core) and non-equilibrium (the corona) components in high-energy nuclear collisions in a unified mannter. The distinct feature of the DCCI model is to reproduce multiplicity dependence of the yield ratio between multi-strange hadrons and pions through a combination of the core and the corona components. This is crutial in describing the small multiplicity events such as p+p, p+A, and peripheral A+A collisions in which the local thermalization of the system is not expected to occur in the whole reaction region.

In this talk, I first show the fractions of the core and the corona components as functions of $dN_{\mathrm{ch}}/d\eta$ from the DCCI model and discuss that the core becomes dominant above $dN_{\mathrm{ch}}/d\eta \sim 20$ [1]. I next demonstrate the anomalous enhancement of the hadron yields in the very low $p_T$ region measured experimentaly could be interpreted as the corona components from fragmentation [2]. I also discuss dynamical initialization of the baryon number and its influence on the fluctuations of the baryon number density in the transverse plane at midrapidity [3].

[1] Y. Kanakubo et al., Phys. Rev. C 105, 024905 (2022).
[2] Y. Kanakubo et al., Phys. Rev. C 106, 054908 (2022).
[3] S. Fujii et al. (work in progress).

Speaker: Tetsufumi Hirano (Sophia University)

Presentation_ID514_Hirano.pptx

129 Probing the Equation of State of Neutron Stars with heavy ion collisions

The equation of state (EOS) is a fundamental property of nuclear matter, crucial for understanding the structure of systems as diverse as atomic nuclei and neutron stars. The importance of studying neutron stars has grown recently due to the observation of gravitational waves from neutron star mergers.

Nuclear reactions involving heavy-ion collisions in laboratories can create nuclear matter similar to that found in neutron stars. However, the density and momentum dependence of the EOS of asymmetric nuclear matter—particularly the symmetry energy term—remains largely unconstrained. Laboratory studies of neutron-deficient and neutron-rich heavy-ion collisions have already provided initial constraints on the EOS of neutron-rich matter at sub-saturation densities.

To establish constraints at higher densities, new experimental measurements and advancements in the theoretical modeling of nuclear collisions and neutron star properties are essential. In this context, we present results from a recent experiment conducted at the National Superconducting Cyclotron Laboratory, which focused on studying the EOS through observables involving charged particles and neutrons, such as neutron-to-proton spectral ratios. We compare the experimental results with various transport model calculations, emphasizing their sensitivity to the density and momentum dependence of the nuclear symmetry potential and their implications for understanding the EOS in neutron star mergers.

Speaker: Zbigniew Chajecki (Western Michigan University)

mdonabc.mp4

mdonabc.mp4.zip

Presentation_ID224_Chajecki_v3.pptx

130 Symmetry energy in dilute and dense matter with extended energy density functionals

Energy density functional (EDF) theory provides a unified framework for the description of nuclei and of infinite nuclear matter. In principle, it facilitates direct connections between nuclear data and the equation of state. In practice, traditional models have strained to describe finite nuclei and infinite systems at the same time. Recently developed extended EDF models overcome many of the limitations of traditional models [1-4]. I will present recent studies of the nuclear symmetry energy within EDF theory and especially the KIDS framework [4], with focus on the curvature of the symmetry energy, indications for a soft-to-stiff transition at supra-saturation densities, and the CREX-PREXII puzzle.
References
[1] Gil et al., Phys. Rev. C 99 (2019) 064319
[2] Gil et al., Phys. Rev. C 103 (2021) 034330
[3] Jun Xu and P.P., Phys. Rev. C 105 (2022) 044305
[3] Zhou et al., Phys. Rev. C 107 (2023) 055803
[4] P.P. and Chang Ho Hyun, Symmetry 15 (2023) 683

Speaker: Panagiota Papakonstantinou (IBS / RISP)

Presentation_ID067_Papakonstantinou.pdf

Presentation_ID067_Papakonstantinou.pptx

Parallel Session: 3_Neutrinos and Nuclei

Convener: Dr Hyunsu Lee (IBS)

131 Double beta decay search of 160-Gd by PIKACHU experiment

160-Gadolinium ($^{160}$Gd) is the candidate nucleus for double beta decay with a high natural abundance, 21.9%, and a low $Q$-value, 1.73 MeV, compared to other candidates. The low $Q$-value makes it difficult to observe even two-neutrino double beta decay (2$\nu$2$\beta$). The previous search using Gd$_2$SiO$_5$ (GSO) crystal [Danevich] has not observed it because of background from Uranium and Thorium (U/Th) decay series contained in GSO. They established 1.9 $\times$ 10$^{19}$ year as the lower limit of 2$\nu$2$\beta$ half-life, while the theoretical prediction of it is 7.4 $\times$ 10$^{20}$ year.
The PIKACHU experiment aims to discover 2$\nu$2$\beta$ using a large Gd$_3$Ga$_3$Al$_2$O$_{12}$ (GAGG) single crystal. It is superior to GSO in terms of light yield, particle identification and content of $^{160}$Gd. We plan to update the lower limit of 2$\nu$2$\beta$ half-life in Phase1 and discover 2$\nu$2$\beta$ with superior sensitivity by approximately one order of magnitude to previous search in Phase2. In this lecture, I’ll introduce the concept of PIKACHU experiment, the development of high purity GAGG, and the present status of data acquisition and analysis for Phase1.
[Danevich] F. A. Danevich, V. V. Kobychev, O. A. Ponkratenko, V. I. Tretyak and Yu. G. Zdesenko, Nucl. Phys. A 694, 375-391 (2001).

Speaker: Takumi Omori (Univ. of Tsukuba)

Presentation_ID16_omori.pptx

132 Study of double beta decay of ${}^{48}$ Ca with CANDLES

The mass origin of neutrinos still remains unknown. One of the possible scenarios is that neutrinos have Majorana masses, which leads to neutrino less double-beta decay (0$\nu\beta\beta$).
CANDLES is a project to search for the 0$\nu\beta\beta$ events of ${}^{48}$Ca, which has the highest Q$_{\beta\beta}$-value of 4.27\,MeV among the double beta decay isotopes. We developed a CANDLES-III detector system with 96 CaF$_2$ scintillation crystals with natural Ca isotope, which corresponds to 350\,g of ${}^{48}$Ca, and took data with almost 3 years of observation, at the Kamioka underground laboratory. We are analyzing data with the various methods to reduce background events to increase a sensitivity to the signal.
In this talk, the analysis of background reduction and the latest status of the search for the $0\nu\beta\beta$ will be reported. We have been developing the key technologies for the next generation detector system, such as isotope enrichment of ${}^{48}$Ca and high energy resolution detector. The current status of these development will be also presented.

Speaker: Sei Yoshida (Osaka University)

Presentation_ID324_Yoshida-v2.pdf

133 Development of Laser Isotope Separation (LIS) of 48Ca for the Study of Neutrinoless Double Beta Decay

Neutrinoless double beta decay (0vββ) is a powerful method for exploring the mysteries of the universe, such as the matter-dominated universe, lepton number violation, and neutrino mass. CANDLES investigated this phenomenon using 48Ca, which has the highest Q-value at 4.23 MeV among the double beta decay nuclides. Nevertheless, a large amount of double beta decay nuclides is required, but 48Ca has a natural abundance of 0.187%. A large-scale production system is being developed to produce 48Ca using laser isotope separation (LIS) with the isotope shift of 48Ca. Isotope separation occurs when incoming photons impart momentum to the target isotope, leading it to diverge from the initial atomic beam. The spatial distribution of the calcium atomic beam was measured using time-of-flight (TOF). This measurement showed a displacement of 48Ca at 3.84 ± 0.83 mm, while no displacement was observed for other isotopes, including 40Ca and 44Ca, when the oscillation wavelength of 48Ca was tuned. This presentation will outline the current statuses, strategies, and requirements for mass production utilizing single-frequency and high-power laser diodes, targeting production rates of 300 kg per year.

Speaker: Anawat Rittirong (RCNP, Osaka University)

Presentation_ID340_RITTIRONG.pdf

Presentation_ID340_RITTIRONG.pptx

134 Neutrinoless double beta decay of hyperons in covariant chiral perturbation theory

The neutrinoless double beta decays of hyperons are studied in chiral effective field theory. The pion mass dependences of the structure functions are discussed, which are helpful for lattice QCD simulations. Numerical results for the branch ratios are obtained, which can be compared with future experimental measurements.

Speaker: Mr Zi-Ying Zhao (Hunan University)

Presentation_ID485_Zhao.pdf

135 Constraints on neutrino wavepackets with the BeEST experiment

Radioactive nuclear decay products are entangled at their creation. Electron capture decays contain just two final state particles: an electron neutrino and a nucleus. Properties of the escaping neutrinos can therefore be determined through measurements of the entangled nuclei. The BeEST experiment implants beryllium-7 directly into superconducting tunnel junctions. After electron capture, the recoil energy of the lithium-7 is measured with unprecedented precision. This measurement is used to place the first direct limits on the size of neutrino wavepackets and paves the way for future tests of quantum mechanics using this novel technique.

Speakers: Annika Lennarz (TRIUMF), Joseph Smolsky (Colorado School of Mines)

110-Lennarz-Smolsky.pptx

136 The current status report of RENE experiment

The Reactor Experiment for Neutrinos and Exotics (RENE) is designed to investigate sterile neutrino in the Δm^2 ~ 2 eV^2 region. The prototype detector of the RENE experiment features a cylindrical target containing Gd-LS (0.5 ton) and two 20’in PMTs in a box-shaped gamma catcher filled with LS (1.5 ton). The baseline distance is ~23 m from the reactor core. The experiment is in the commissioning phase, with the prototype detector on the ground to prepare the first data-taking at the tendon gallery of the Hanbit Nuclear Power Plant. This presentation will provide the current preparation status for the RENE experiment.

Speaker: Dong Ho Moon (Chonnam National University)

INPC_dhmoon_20250527_RENE_Status_final_v1.pdf

Parallel Session: 3_New Facilities and Instrumentation

Convener: Robert Bark (iThemba LABS)

137 SCRIT electron-scattering facility for short-lived exotic nuclei

Electron scattering has long been regarded as the gold standard for probing nuclear structures, playing a crucial role in uncovering the internal composition of atomic nuclei and shaping our modern understanding of their properties. Until recently, however, its application has been strictly confined to stable nuclei, leaving short-lived unstable nuclei entirely unexplored*.

After nearly two decades of development, we have recently achieved a groundbreaking milestone: the first electron scattering experiment on an online-produced radioactive isotope at the SCRIT electron-scattering facility of the RIKEN RI Beam Factory in Japan**.

The SCRIT facility, designed specifically to investigate the internal structures of short-lived exotic nuclei via electron scattering, leverages the innovative SCRIT (Self-Confining Radioactive Isotope Ion Target) technique***. With as few as ~10⁷ ions of an exotic nucleus, this technique enables a luminosity of approximately 10²⁷ /cm²/s—sufficient to conduct elastic electron scattering on medium-heavy nuclei.

In this presentation, I will highlight recent achievements and the current status of the SCRIT facility while also discussing the broad range of research opportunities the SCRIT facility may open for future exploration.

• T. Suda and H. Simon, Prog. Part. Nucl. Phys. 96 (2017) 1-31.
  ** K. Tsukada et al, Phys. Rev. Lett. 131 (2023) 092502.
  Physics Today 76 (11), 14–16 (2023).
  *** M. Wakasugi, T. Suda and Y. Yano, Null. Instrum. Methods A532 (2004) 216.

Speaker: Toshimi Suda (Tohoku University)

Presentation_ID306_Suda.pdf

138 Status of Barrel Imaging Calorimeter in Korea for the Electron-Ion Collider

The Electron-Ion Collider (EIC) is a next-generation particle accelerator facility designed to probe the fundamental structure of matter such as the origins of nucleon mass, spin, and the dynamic behavior of quarks and gluons within nucleon and nucleus. As the electromagnetic calorimeter in the barrel region, the Barrel Imaging Calorimeter (BIC) is tasked with precise energy measurements of electrons and photons as well as efficient separation of these particles from background pions. The BIC integrates Pb/SciFi sampling layers and AstroPix silicon pixel sensors for three-dimensional shower imaging. The Korean group has actively contributed through silicon chip testing, module assembly, prototype development, beam test, readout system design, and detailed simulations. This presentation highlights the recent progress and plans for the R&D of the Barrel Imaging Calorimeter in Korea.

Speaker: Jeongsu Bok (Pusan National University)

250527_INPC_jbok_BIC_rev2.pdf

139 Production of the prototype Pb/SciFi calorimeter of the Barrel Imaging Calorimeter for the Electron-Ion Collider

The ePIC experiment at the Electron-Ion Collider (EIC) seeks to uncover the fundamental structure of nucleons and nuclei. The Barrel Imaging Calorimeter (BIC) is an important detector designed to provide high energy and position resolution for photons and electrons. As part of its development, a prototype BIC was built and subjected to a beam test at the CERN PS beamline. In the beam test, calibration and energy measurement under realistic conditions were conducted. Each 3×3×32 cm^3 Pb/SciFi module was assembled by layering swaged lead plates with scintillating fibers, which were then bundled and read out by photomultiplier tubes to detect signals from electromagnetic showers. A prototype assembly, arranged in a 3x5 matrix of these unit modules, was deployed to evaluate energy response. In this talk, we present the design, assembly, and beam-test preparations for the prototype BIC. These efforts will validate the Pb/SciFi bulk domain performance and help refine the manufacturing process in anticipation of full-scale production.

Speaker: Sangwoo Park (Sungkyunkwan University)

INPC2025_sw.pdf

140 Deblurring process on the triple-differential yield and collective flow in heavy-ion collisions

The triple-differential yield as functions of the transverse momentum, the rapidity and the azimuthal angle relative to the estimated reaction plane is a critical observable for the collective-flow analysis in heavy-ion collisions. However, the signal could be degraded by imperfect detector performance such as the detection inefficiency and partial coverage of the acceptance in phase space. In optics the Richardson-Lucy deblurring algorithm was invented and applied to the degraded intensity distributions to recover the original images. Inspired by this analysis technique in optics, the dedicated deblurring algorithm for heavy-ion collisions has been developed and applied to the flow analysis for $^{132,108}$Sn + $^{124,112}$Sn at 270 AMeV by the SPiRIT Collaboration. In this presentation, we describe the principle of the deblurring process using the Richardson-Lucy algorithm to restore the original triple-differential particle distributions, which may exhibit different features of the collective flow, compared to the results without applying the deblurring process.

Speaker: Jeonghyeok Park (Korea University)

Presentation_ID419_Park.pdf

141 Towards nuclear structure studies using trapped antiprotons at AEgIS

On behalf of the AEgIS collaboration

At CERN's antimatter factory, antiprotons are routinely produced and cooled in bunches utilizing the ELENA/AD decelerators. The low energy antiprotons are distributed to a wide range of trapping experiments primarily aiming at precision tests of fundamental symmetries and interactions [1]. The Antimatter Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) at the antimatter factory has achieved remarkable performance in using trapped antiprotons for the pulsed creation of antihydrogen for studying the gravitational influence on antimatter and in laser cooling of positronium [2, 3, 4]. Currently, the involved techniques are being extended to the controlled synthesis of antiprotonic atoms inside the Penning-Malmberg trap, where an antiproton—nearly 2000 times heavier than an electron—replaces an orbiting electron in a conventional atom [5, 6].

The transitions between the deeply bound states of an antiprotonic atom are influenced by the strong interaction and can in some cases induce direct nuclear resonance effects, offering insight into the nuclear density and spin of short-lived states via X-ray spectroscopy [7]. As the bound antiproton deexcites after being captured in a Rydberg state, it ejects atomic electrons via the Auger processes before annihilating at the nucleus's surface, resulting in the formation of highly charged nuclear annihilation fragments. These highly charged ions (HCIs) can be trapped and further cooled for experimental studies [8, 9]. Measurements of the yields of the captured nuclear fragments give valuable insight into the annihilation mechanism, opening avenues for precision studies of nuclear structure, such as the neutron-skin [10, 11].

As an initial step towards this goal, the AEgIS collaboration has demonstrated the trapping and TOF spectroscopy of HCIs, produced by antiproton annihilations on Argon and Helium atoms inside the Penning-Malmberg trap. Meanwhile, the ongoing installation of a negative ion source will enable co-trapping of negative ions with antiprotons for the laser-triggered formation of antiprotonic atoms. These developments lay the groundwork for controlled synthesis and spectroscopy of cold radioactive HCIs, advancing studies of fundamental interactions and nuclear structure.

[1] Carli, C., et al. Nuclear Physics News 32.3 (2022): 21-27.
[2] Doser, M., et al. Classical and Quantum Gravity 29.18 (2012): 184009.
[3] Amsler, C, et al. Communications Physics 4.1 (2021): 19.
[4] Glöggler, L. T., et al. Phys. Rev. Letters 132.8 (2024): 083402.
[5] Doser, M. Progress in Particle and Nuclear Physics (2022): 103964.
[6] Rodin, V, et al. JACoW IPAC 2022 (2022): 2126-2129.
[7] Gustafsson, Fredrik P., et al. Phys. Rev. C 109.6 (2024): 064320.
[8] Kornakov, G., et al. Phys. Rev. C 107.3 (2023): 034314.
[9] Blaum, K., et al. Quantum Science and Technology 6.1 (2020): 014002.
[10] Lubiński, P., et al. Phys. Rev. C 57.6 (1998): 2962.
[11] Trzcińska, A., et al. Phys. Rev. Letters 87.8 (2001): 082501.

Speaker: Fredrik Parnefjord Gustafsson (CERN)

Presentation_ID701_ParnefjordGustafsson.pptx

142 Status of the CAGe germanium detector array at the IBS Center for Underground Physics

The IBS Center for Underground Physics (CUP) operates a number of rare-event search experiments, including the AMoRE double-beta-decay search and the COSINE dark-matter search, previously operating at the Yangyang Underground Laboratory in Yangyang, Korea, with new operations now moved to the newer Yemilab facility. Such experiments require extensive radioactivity assay of the detector materials. As such, CUP has developed and maintained a number of assay facilities and methods, including multiple high-purity germanium (HPGe) detectors. The CAGe is a particularly unusual array of fourteen 70% relative-efficiency HPGe detectors, designed in collaboration with Mirion Technologies, and operated by CUP at Yemilab since 2017. It has been used primarily to measure trace radioactivity in materials with particularly stringent assay requirements, especially for the AMoRE experiment, and is now being used for physics searches as well. This talk will present the status, operation, and performance of the CAGe detector system in the context of these measurements, its potential for physics searches, and the upcoming move to Yemilab.

Speaker: Douglas Leonard (IBS Center for Underground Physics)

Leonard-INPC2025.pdf

Parallel Session: 3_Nuclear Astrophysics

Convener: Iris Dillmann (TRIUMF)

143 Impact of newly measured beta-delayed neutron data for nuclei close to 78Ni on light-element nucleosynthesis in neutron star mergers

How different astrophysical events contribute to the synthesis of elements heavier than iron and in particular the role of the rapid (r) neutron capture process, remains an actively debated topic [1]. The r-process was recently observed in the kilonova emission accompanying the unique detection of gravitational waves from the neutron star merger event GW170817 [2]. The EM early emission is dominated by the presence of freshly produced light r-process elements and there is evidence for the observation of Sr [3]. A promising approach to investigating the r-process is to study elemental abundances in the atmosphere of old ultra metal-poor (UMP) stars, which likely collected elements from only one or a few nucleosynthesis events. This can be then compared to calculations based on models of different astrophysical events which together with the nuclear data input are able to predict abundances. A difficulty here is the blurring effect induced by nuclear data uncertainties. In particular in the case of the r-process that runs far away from beta-stability, decay data is obtained from theoretical models with modest predictive power [4].

In this contribution, we present new experimental values of decay half-lives and neutron emission probabilities of 37 very neutron-rich nuclei ranging from 75Ni to 92Br, measured at the RIKEN Nishina Center in Japan, including 11 one-neutron and 13 two-neutron emission probabilities and 6 half-lives determined for the first time [5].

We further investigate the impact of our data on the final abundances produced by a weak r-process, which synthesizes first-peak r-process elements. This process occurs in neutrino-driven winds following a neutron star merger. To do that, we use a comprehensive set of simulated thermodynamical trajectories that describe the evolution of matter properties in the merger outflows [6]. We find a sizable increase in the calculated abundances of Y, Zr, Nb and Mo using our data, significantly larger than the spread on relative abundances observed in UMP stars [7]. This emphasizes the necessity of using reliable experimental decay data for very neutron-rich beta-delayed neutron emitters in r-process models to ensure meaningful comparisons with observational data.

[1] A. Arcones et al., Astron. & Astroph. Review 31, 1 (2023)
[2] D. Kasen et al. Nature 551, 80 (2017)
[3] D. Watson et al., Nature 574, 497 (2019); N. Vieira et al., Astroph. J. 944, 123 (2023)
[4] P. Moeller et al., At. Data and Nucl. Data Tables 125, 1 (2019)
[5] A. Tolosa-Delgado, PhD Thesis, University of Valencia (Spain), 2020
[6] D. Martin et al., Astroph. J. 813, 2 (2015)
[7] I. U. Roederer et al., Astroph. J. 936, 84 (2022)

Speaker: Jose L. Tain (IFIC, CSIC-U.Valencia)

Presentation_ID591_Tain.pdf

144 KISS/KISS-1.5 to explore the origin of heavy elements synthesized by r-process from their nuclear spectroscopy

The KEK Wako Nuclear Science Center (WNSC) has developed the KEK Isotope Separation System (KISS) [1] at RIKEN to study the nuclear structure of the nuclei in the vicinity of neutron magic number N = 126, trans-uranium elements, and actinides. This research aims to explore the origin of heavy elements synthesized by the rapid neutron capture process. These neutron-rich nuclei have been produced by using multinucleon transfer (MNT) reactions [2] with the combinations of the low-energy $^{136}$Xe/$^{238}$U beams and the production targets of W, Ir, and Pt. At the KISS facility, these radioisotopes are ionized by applying in-gas-cell resonant laser ionization technique. Their nuclear spectroscopy, including decay studies at a beta-gamma decay station [3], precise mass measurements using MRTOF-MS [4], and laser spectroscopy [5] have been successfully performed.

To further conduct this research, WNSC have recently started the construction of KISS-1.5 [6], which will provide much higher yields of MNT products for nuclear spectroscopy.

In the talk, we will introduce the KISS facility, report the recent experimental results, and discuss future perspectives at KISS-1.5.

References
[1] Y. Hirayama et al., Nucl. Inst. Meth. B353, 4 (2015), and B412, 11 (2017).
[2] Y.X. Watanabe et al., Phys. Rev. Lett. 172503, 1 (2015).
[3] M. Mukai et al., Nucl. Inst. Meth. A884, 1 (2018), Y. Hirayama et al., NIMA997, 165152 (2021).
[4] P. Schury et al., Nucl. Inst. Meth. B317, 537 (2013).
[5] Y. Hirayama et al., PRC96(2017)014307, PRC106(2022)034326, M. Mukai et al., PRC(2020)054307, and H. Choi et al., PRC102(2020)034309.
[6] Design report of the KISS-II facility for exploring the origin of uranium, arXiv:2209.12649.

Speaker: Yoshikazu HIRAYAMA (WNSC, IPNS, KEK)

Presentation_ID181_HIRAYAMA_mod.pdf

145 Experimental study on the $\gamma$-emission probability of unbound states in $^{131}$Sn for understanding r process

The rapid neutron capture process, $\textit{r}$ process, is an important pillar of stellar nucleosynthesis, which is responsible for the production of more than half of the elements heavier than iron. However, the physical conditions and astronomical sites for $\textit{r}$ process have not been determined because of the lack of experimental data for the properties of involving exotic nuclei.
One of the critical isotopic regions in $\textit{r}$ process is the area near $^{132}$Sn, which has the neutron magicity with 82 neutrons. A drastic decrease of the neutron capture rate when crossing the neutron magic number is expected for the compound neutron capture due to the large energy gap after the shell closure. Due to a lack of experimental data, there are large uncertainties in neutron capture rates, which result in the large ambiguity in $\textit{r}$-process conditions and make the calculation of final elemental abundance of $\textit{r}$ process undetermined.
The neutron capture rates can usually be determined with the knowledge of $\gamma$-emission probabilities of the neutron unbound states. However, the low $\gamma$-emission probabilities and usually low $\gamma$-ray detection efficiency have been the experimental obstacles. At the OEDO-SHARAQ beamline in RIKEN RIBF, an alternative method to identify experimental $\gamma$-emission probability was developed, in which the reacted heavy residues are identified with the SHARAQ spectrometer, and the $\gamma$-emission probability can be obtained based on the number of heavy residues with increased neutron number. A $^{130}$Sn($\textit{d}$,$\textit{p}$) experiment was conducted with this method to identify the $\gamma$-emission probabilities of the neutron unbound states in $^{131}$Sn. The kinetic energy of $^{130}$Sn beam was degraded to about 20 MeV/u for the one neutron transfer reaction at OEDO beamline. We identified Sn isotopes with A = 129, 130, and 131, which correspond to two, one, and zero neutron emissions after the reaction, respectively. The features of this experiment and the preliminary results on the identified Sn isotopes after the $^{130}$Sn($\textit{d}$,$\textit{p}$) reaction will be presented.

Speaker: Dr Sunghan Bae (Center for Nuclear Study, the University of Tokyo)

Presentation_ID220_Bae.pdf

146 Exploring the origin of neutron-capture elements through heavy-element enhanced metal-poor stars

The origin of neutron-capture elements remains a mystery, but heavy element-enhanced metal-poor stars, as the natural laboratory that exists in the Universe, provide unique information to solve the mystery. We selected 84 very metal-poor stars with -3.3 < [Fe/H] < -1.6 based on a joint project with LAMOST and Subaru, and presented a homogeneous abundance analysis of 16 neutron-capture elements. 1) We find that the origin of r-I and r-II stars is related to their birth environment, while the s-process has already contributed to the chemical enrichment of the Milky Way galaxy at extremely low metallicity at [Fe/H]~-2.6. 2) We discovered for the first time an r-process enhanced actinide-boost star in the GSE substructure, whose complete abundance pattern can provide important information about the r-process nucleosynthesis in GSE. 3) The sample also includes two CEMP-r+s stars, which doubles the sample size of these very rare objects. We find a significant difference between CEMP-r/s and CEMP-r+s stars in the [ls/hs] and [Pb/Fe] distribution. This indicates that neutron-capture elements in these two types of stars may have their own unique origins, and will shed new lights concerning the puzzling origin of these elements.

Speaker: Yangming Lin (National Astronomical Observatories)

Presentation_ID301_Lin.pptx

Parallel Session: 3_Nuclear Reactions (1)

Convener: Yoshihiro Aritomo (Kindai University)

147 Nuclear reactions from the ab initio symmetry-adapted no-core shell-model framework

I will discuss recent developments for constructing translationally invariant nonlocal optical potentials rooted in first principles and applicable to spherical and deformed targets up through the Ca region. First studies are now available for proton/neutron and deuteron projectiles at low energies and for light-mass targets. These applications build upon the merging of two successful approaches, namely, the Green's function technique and the ab initio symmetry-adapted no-core shell model that has expanded the reach of practically exact methods to medium-mass open-shell nuclei. I will also discuss uncertainty quantification for reaction observables that includes not only uncertainties that stem from the many-body approach but also from the underlying chiral parameterization. As an interesting application to quantum computing, we use these inter-cluster potentials to study the efficacy of various types of qubit mapping and provide first quantum simulations for Carbon isotopes.

[We acknowledge the support from the U.S. Department of Energy (DE-SC0023532, DE-SC0023694). This work benefited from high performance computational resources provided by LSU, NERSC, and the Frontera computing project.]

Speaker: Kristina Launey (Louisiana State University)

Presentation_ID450_Launey.pdf

148 A full-microscopic approach for sub-Coulomb-barrier reactions.

In this presentation, we will discuss a method for fully microscopic description of scattering states and many-body quantum tunneling by combining time-dependent Hartree-Fock (TDF), antisymmetrized molecular dynamics (AMD), and the generator coordinate method (GCM). In ordinary TDHF and AMD, the motion along the reaction path is classical, making it difficult to discuss quantum effects such as tunneling. To overcome this limitation, we propose a new framework combining time-dependent microscopic models with GCM. In the presentation, we will explain this framework and demonstrate numerical calculations showing that this approach can describe quantum phenomena such as sub-Coulomb-barrier tunneling.

[1] M. Kimura and Y. Taniguchi, PTEP 2024, 093D01 (2024).

Speaker: Masaaki Kimura (RIKEN Nishina Center)

Presentation_IDxxx_kimura.pptx

149 TDRPA Calculations for Mass and Charge Fluctuations and Correlations in 144,154Sm+144,154Sm reactions

Time-dependent mean-field approaches, such as time-dependent Hartree-Fock (TDHF) or time-dependent density functional theory (TDDFT), have shown remarkable successes in describing nuclear excitations and dynamics microscopically. Especially, recent TDHF (with or without addition of pairing correlations) calculations have shown that the main (or average) reaction outcomes can be described quantitatively without adjustable parameters on reaction dynamics (see, e.g., Ref. [1]). Further developments of the theoretical framework and its applications can thus be considered to be promising to develop our understanding of complex reaction mechanisms in low-energy heavy-ion reactions.

However, there is a well-known, longstanding drawback inherent in the standard TDHF approach, that is, it severely underestimates width of fragment mass and charge distributions. Recent theoretical efforts have shown that this drawback can be overcome by incorporating one-body fluctuations and correlations on top of the average (TDHF) trajectory, based on, e.g., time-dependent random phase approximation (TDRPA) (see, e.g., Ref. [2] and references therein) or stochastic mean-field theory (SMF) [3]. Although those approaches have shown successful reproductions of existing experimental data (see, e.g., Refs. [4, 5]), we need further systematic calculations in comparison with available experimental data, to unveil underlying reaction mechanisms.

To this end, we have conducted TDRPA calculations for $^{144}$Sm+$^{144}$Sm (spherical+spherical) and $^{154}$Sm+$^{154}$Sm (deformed+deformed) systems for which old, yet great experimental data are available [6]. For the latter deformed system, several relative orientations were investigated. From the results, we have found that total kinetic energy loss (TKEL) as a function of fragment mass dispersion agrees quantitatively with experimental data. On the other hand, TDRPA tends to overestimate charge dispersion, which may be improved by refining the energy density functional (EDF). Moreover, we have performed systematic analysis of mass and charge dispersion with Ni+Ni, Sm+Sm, Yb+Yb, Pb+Pb systems (and some others will be added) to seek for a universal behavior of fragment mass and charge fluctuations. In this talk, we will present the latest TDRPA analysis of fragment mass and charge fluctuations and correlations and discuss the physics behind the dissipative collisions of heavy nuclei.

[1] K. Sekizawa, Front. Phys. 7, 20 (2019).
[2] C. Simenel, Eur. Phys. J. A 48, 152 (2012).
[3] S. Ayik, Phys. Lett. B658, 174 (2008).
[4] E. Williams, K. Sekizawa, D. Hinde et al., Phys. Rev. Lett. 120, 022501 (2018).
[5] K. Sekizawa and S. Ayik, Phys. Rev. C 102, 014620 (2020).
[6] K.D. Hildenbrand et al., Nucl. Phys. A405, 179 (1983).

Speaker: Dr Kazuyuki Sekizawa (Institute of Science Tokyo)

Presentation_ID161_Sekizawa.pptx

150 A complex scaling method for efficient and accurate scattering emulation in nuclear reactions

Uncertainty quantifications are crucial in nuclear reaction calculations. We present a novel scattering emulator utilizing the complex scaling method to enhance nuclear reaction analysis. This approach leverages a single set of reduced bases, allowing for efficient and simultaneous emulation across multiple channels and potential parameters, significantly reducing computational storage and accelerating calculations. Demonstrated through n+40Ca and 11Be+64Zn elastic scattering, our method achieves high accuracy and efficiency. This emulator exhibits stable and reliable performance without anomalies inherent in other techniques, showcasing its robustness.

Speaker: Junzhe Liu (School of Physics Science and Engineering, Tongji University)

Presentation_ID27_Liu.pdf

151 Pre-compound Emission Modeling for Alpha Induced Reactions via Machine Learning and Bayesian Algorithm

Pre-equilibrium or Pre-compound emission plays an important role in the dynamics of nuclear reactions, particularly, in light-ion-induced nuclear reactions, where it significantly influences the cross-section of reaction products [1-4]. This study presents a novel approach to model the pre-compound emission using machine learning techniques combined with Bayesian algorithms. By leveraging the probabilistic framework of Bayesian analysis, in the present paper a predictive model capable of estimating pre-compound emission yields with high accuracy, considering various entrance channel parameters is presented. The model is trained on extensive data from alpha-induced nuclear reactions, incorporating factors such as atomic mass and number of interacting partners, excitation energy, reaction Q-value, and other nuclear structure effects.

In the present work, the experimentally measured pre-equilibrium fraction, which is the contribution of pre-equilibrium emission, for 14 projectile-target combinations from ref. [3] have been used. In the model, 10 entrance channel parameters with 190 data points have been utilized to train the neural network. A feed-forward Levenberg-Marquardt network of one hidden layer with 20 neurons along with 10 input neurons and one output neuron is used. For the estimation of contribution of pre-compound emission 80% of data points were used for training and several attempts have been made to minimize the R2 values. The model could satisfactorily predict the preequilibrium cross-section, which satisfactorily matched with the experimental one. The details of the model and calculations will be presented during the conference.

References:

M. Blann, Phys. Rev. Lett. 27, 337 (1971).

P. E. Hodgson, Nature (London) 292, 671 (1981).

L. Westerberg, et al., Phys. Rev. C 18, 796 (1978).

M. K. Sharma, et al., Phys. Rev. C 110, 024613 (2024).

Speaker: Dr Unnati Gupta (Amity University)

Presentation_ID629_Gupta.pdf

152 Ternary fission analysis using Skyrme Energy density formalism

The spontaneous disintegration of unstable nuclei encompasses various decay modes such as $\alpha$-decay, spontaneous fission and ternary fission etc. Ternary fission, involving the simultaneous emission of three fragments, is a relatively rare phenomenon. An appropriate understanding of this process is essential for the incorporation of the dynamics of complex nuclear fragments emitted via heavy nuclei. These fragments play a pivotal role in the overall understanding of the decay dynamics and related properties of radioactive nuclei and may also contribute to the production of new isotopes near and beyond the drip line region. Experimental and theoretical studies show that ternary fission can occur as equatorial cluster tripartition (ECT) or collinear cluster tripartition (CCT) depending on the direction of the emitted third fragment with respect to the fission axis \cite{shell} . The spontaneous ternary emission was observed experimentally for $^{252}$Cf nucleus \cite{exp}, where the isotopes of H, He, Li, Be, B, C, N, O, F, Ne, Na, Al, Mg are detected. Studies \cite{balu,exp} emphasize the observation of alpha particles as the predominant third fragment in ternary fission. The main reason for this radioactive splitting is the shell closure effect associated with the daughter nucleus. Hence, it will be of interest to explore the fragmentation behavior of the ternary decay mode of heavy nuclei by employing variety of nuclear potentials.\
In order to understand the nuclear dynamics, selecting an appropriate nuclear interaction potential is crucial. Numerous theoretical models are introduced to explore fission dynamics based on different nuclear properties. The two most commonly used approaches for calculating nucleus-nucleus potentials are the phenomenological and microscopic methods. The phenomenological model approximates the nuclear interaction potential based on the closeness of the surfaces of interacting nuclei. Whereas, the microscopic approach treats the nuclei using a mean-field approximation where the total energy of a nuclear system is expressed as a function of the nucleon densities.
In the present study, an effort is focused on understanding the relevance of such approaches in the ternary decay mechanisms of the $^{252}$Cf.

Speaker: Mr Manoj K Sharma (Thapar Institute of Engineering and Technology,Patiala)

Presentation_ID020_Sharma.pdf

Parallel Session: 3_Nuclear Reactions (2)

Convener: Yung Hee KIM (CENS)

153 Heavy-ion induced single and double charge exchange reactions in a multi-channel approach: new results from the NUMEN project

In order to get quantitative information on neutrino absolute mass scale from the possible measurement of the 0νββ decay rates, the Nuclear Matrix Elements (NME) involved in such transitions are required. Recently, heavy-ion induced double charge exchange (DCE) reactions have been proposed in Italy [1-2] and Japan [3,4] as tools to get information about 0νββ NMEs. The basic point is that there are important similarities between the two processes, mainly that the initial and final states are the same and the transition operators have a similar structure, including in both cases a superposition of Fermi, Gamow-Teller and rank-two tensor components [5].
The NUMEN project at INFN-LNS laboratory in Italy proposes to explore the whole network of direct nuclear reactions connecting the initial and final nuclear states of the ββ-decay. This includes DCE, Single Charge Exchange (SCE), multinucleon transfer reactions, elastic and inelastic scattering. A key aspect is the consistent investigation of all the above reaction channels. This multi-channel approach demands that: i) the cross sections for all the relevant reaction channels are measured under the same experimental conditions; ii) the data analysis is performed in the framework of the microscopic quantum reaction theory in a model space large enough to include all the reaction channels and adopting consistent nuclear structure inputs.
Experimental campaigns have been performed at INFN-LNS in order to explore heavy ion induced reactions on target of interest for 0νββ decay. These studies are complemented by a strong activity on the theoretical side, especially tailored to give a detailed description of the challenging DCE reaction mechanisms [6-7]. An overview of recent activity performed in Catania in this field will be presented at the INPC2025 Conference.

References
[1] Cappuzzello, F. et al., Eur. Phys. J. A 54:72 (2018)
[2] Cappuzzello, F. et al., Int. Jour. of Mod. Phys. A 36, 2130018 (2021)
[3] Takaki, M. et al., RIKEN Accelerator Progress Report 47 (2014)
[4] Sakaue. A. et al., Prog. Theor. Exp. Phys. 123D03 (2024)
[5] Cappuzzello, F. et al., Eur. Phys. J. A 51: 145 (2015)
[6] Lenske, H. et al., Prog. in Part. and Nucl. Phys. 109 103716 (2019)
[7] Cappuzzello, F. et al., Prog. in Part. And Nucl. Phys., 128 103999 (2023)

Speaker: Diana Carbone (INFN-LNS)

Presentation_ID104_Carbone.pdf

154 Visualizing Interference Effects in Elastic α + 40Ca Scattering Using Fourier Transform

We study interference effects in elastic α + 40Ca scattering at Elab = 29 MeV using an optical potential model. The scattering amplitude is decomposed into near-side and far-side components, further divided into barrier-wave and internal-wave parts. Each component uniquely shapes the angular distribution. Applying Fourier transform techniques, we visualize interference patterns and identify peaks at specific scattering angles. This analysis reveals structural features beyond what is evident in differential cross sections.

Speaker: Kyoungsu Heo (Soongsil Univ.)

Presentation_ID673_Heo.ppsx

155 Measurements of pd elastic and inclusive breakup reactions at 230MeV for the study of elementary process of deuteron knock-out reactions

The effects of three-nucleon force (3NF) have been actively studied by using the nucleon-deuteron (Nd) scattering states. The differential cross sections of the elastic Nd scattering at the energy below 150 MeV can be well reproduced by the Faddeev calculation based on modern nucleon-nucleon (NN) interactions and 3NF. On the other hand, the data at 250 MeV was underestimated by the calculations with 3NF by 50%. And this large discrepancy between the data and the theory was also shown in the 2H(p, p)pn inclusive breakup reaction at forward angular region [1].
Now, we are working on the ONOKORO project, which aims to understand the formation of various clusters (d, t, 3He, alpha) within nuclei. In this project, a detailed understanding of knockout reactions is important, and the measurement of the pd breakup reaction as an elementary process plays an important part because deuteron cluster is rather fragile [2]. We had carried out new inclusive pd breakup reaction measurements at RCNP, Osaka university as part of this project.
We injected 230MeV proton beam onto the deuterated poly-ethylene (CD2) target which is used as a deuteron target, and detected scattered protons by using Grand-Raiden spectrometer (for theta_LAB = 27 – 61 degree) or LAS spectrometer (for theta_LAB = 27 – 98 degree). We got the numbers of yield of breakup reaction which is summed up to 10MeV excitation energy, and then deduced the angular distributions of the differential cross sections of inclusive breakup reactions. From the comparison, the theoretical calculation [2] was shown to reproduce experimental data well.

[1] S. Kuroita, et al., Few-Body Systems 50, 287 (2011).
[2] Y. Chazono, et al., PRC 106, 064613(2022).

Speaker: Yukie Maeda (University of Miyazaki)

Presentation_ID610_Maeda_v2.pptx

156 Further test of applying the envelope method to the optical potential ambiguity problem

Optical potential is an important input quantity for the calculations of nuclear reactions. Usually, the optical potentials are obtained by fitting the experimental elastic scattering angular distributions. Through this approach, for a specific colliding system, several potential sets can be obtained with nearly equally good agreements. This is the long-standing optical potential ambiguity problem. However, it is found that the ambiguous potentials may exhibit different nearside/farside behaviors. On the other hand, the envelope method proposed by da Silveira and Leclercq-Willain can be used to decompose the experimental angular distribution data into positive-/negative-deflection-angle components. Inspired by the two aspects, we have developed an approach to deal with potential ambiguity problem based on the envelope method in our previous paper. In this approach, the theoretical nearside/farside angular distributions are compared with the “experimental” ones given by the envelope method to select the more physical potential set. The validity and capability of this approach for the “refractive/surface-transparent” potential ambiguity problem have been discussed by applying it to the colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV. In the present work, this approach is tested further by applying it to the colliding systems of 16O+12C at 608 MeV and 1503 MeV. It is found that this approach is useful to deal with the shallow- or deep-W ambiguity.

References
[1] M.S. Hussein, K.W. McVoy. Nearside and farside: the optics of heavy ion elastic scattering. Prog. Part. Nucl. Phys., 12, 103–170 (1984).
[2] R. da Silveira, Ch. Leclercq-Willain. On the separation of the nuclear and Coulomb rainbow components from the elastic scattering data. Z. Phys. A At. Nucl., 314, 63–67 (1983).
[3] L.Y. Hu, Y.S. Song. Trial application of the envelope method to the potential ambiguity problem. Nucl. Sci. Tech., 35, 8 (2024).

Speaker: Dr Liyuan Hu (College of Nuclear Science and Technology, Harbin Engineering University)

Presentation_ID350_Hu.pdf

Presentation_ID350_Hu.pptx

Parallel Session: 3_Nuclear Structure (1)

Convener: Tim Enrico Lellinger (Max Planck Institute for Nuclear Physics)

157 Shell-model calculations for describing shape coexistence of Zr and the neighboring isotopes

Zr isotopes exhibit a sudden change of nuclear shape from spherical to deformed at $N=60$ as can be seen by the jump of the $B(E2)$ transition strength from the lowest $2^+$ state to the ground state. This shape transition results from the shape coexistence of spherical and deformed bands at low energy. $^{100}\text{Zr}$ $(N=60)$ is deformed more easily than $^{98} \text{Zr}$, which is a subshell closure of $N=58$, so a deformed $0^+$ state comes down below the spherical $0^+$ state at $N=60$.
The detailed nuclear structure has been described particularly by Monte Carlo shell model (MCSM) calculations. Comparing the results with recent gamma-ray spectroscopy, we can however find some discrepancies between the MCSM calculations and experiment for the energy spectra and $B(E2)$ transition strengths.
In this talk, we present a recent study by using the Quasi-particle vacua shell model (QVSM) calculations. In the QVSM, a nuclear wave function is expressed with a superposition of quasi-particle vacua. The U and V matrices, which characterize each basis vector, are optimized to describe some low-lying states. We developed a phenomenological effective interaction which can be applied to describe not only Zr $(Z=40)$ isotopes, but also Kr $(Z=36)$, Sr $(Z=38)$, Mo $(Z=42)$, and Ru $(Z=44)$ for $N=50-70$. We are successful in systematically reproducing energy spectra and $B(E2)$ strengths. We discuss the magnitude of deformation, triaxiality, and the mixing of different shapes based on the analysis of wave functions obtained by the QVSM calculations. In contrast to Zr isotopes, the Kr, Sr, Mo, and Ru isotopes exhibit more gradual shape transitions. Our calculations reproduce this trend and describe the detail of shape coexistence in those isotopes.

Speaker: Kota Yanase (RIKEN)

384_Yanase.pptx

158 Shape coexistence in 94-96Zr from low energy Coulomb-excitation experiments with the AGATA-SPIDER array.

The study of shapes and collective properties of atomic nuclei is a vast area of research, and low-energy Coulomb-excitation is one of the most powerful experimental techniques for such studies. It provides information not only about the reduced transition probabilities, describing the collectivity of the transitions, but also about the spectroscopic quadrupole moments of excited states, as well as the relative signs of the extracted transitional and diagonal matrix elements.
Typically, following low-energy Coulomb-excitation experiments, a set of matrix elements is determined allowing for the use of the Kumar–Cline’s sum rules that permit the determination of the deformation parameters together with their widths.
Coulomb excitation measurements have been performed to study structural changes and the presence of coexisting shapes in the zirconium isotopes, which are particularly interesting as, in recent years, evidence has come to light that they are excellent cases for exhibiting type II shape evolution.
In most cases, however, the nuclear matrix elements required to perform precision tests of state-of-the-art nuclear theory in this region are lacking.
For this reason we decided to perform Coulomb excitation measurement allowing for an in-depth comparison with theoretical predictions, shedding light on the structure of low-lying excitations in these nuclei.
In this talk, our experimental results will be presented focusing on the Coulomb-excitation measurement performed on the 94-96Zr isotope using the γ-ray tracking spectrometer AGATA coupled with the heavy-ion detector array SPIDER at INFN-LNL.

Speaker: Adriana Nannini (INFN Sezione di Firenze)

Presentation_ID5_Nannini.pdf

159 Two-Phonon Octupole excitation in 96Zr

We present the preliminary analysis of an experiment performed at INFN LNL in November 2023 aimed at studying the two-octupole phonon collectivity in Zr. The goal of the experiment was to perform a -decay branching ratio measurement from the 6$^{+}$ to the 3$^{-}$ state, so as to extract the B(E3; 6$^{+}\rightarrow 3^-$) value. If large, this parameter would indicate for the level to be a member of the 3$^{-}$$\otimes$ 3$^{-}$multiplet. The state was populated via the $^{96}$Zr(p,p’)$^{96}$Zr proton inelastic scattering and the scattered protons were measured in the SAURON Double-Sided Silicon Strip detector. These were used to select the reaction channel of interest, in coincidence with the rays in the AGATA array.

Speaker: Damiano Stramaccioni (University of Padova and INFN Laboratori Nazionali di Legnaro)

Presentation_ID53_Stramaccioni.pdf

160 Triaxial deformation in neutron-rich Zr and Mo isotopes explored by high-resolution in-beam gamma-ray spectroscopy

Since the nuclear collective model was first proposed by Rainwater, and later refined by Bohr and Mottelson, the axially symmetric deformation with rotational motion has successfully described many nuclei. However, certain exotic nuclei require additional degrees of freedom to explain their rotational motion, particularly in relation to the $\gamma$-band structure. To address such cases, triaxial deformation was introduced, characterized by the gamma degree of freedom spanning from 0$^{\circ}$ (prolate) to 60$^{\circ}$ (oblate).

To describe this triaxial motion, Davydov and Filippov developed a rigid triaxial rotor model, which predicts that the second 2$^{+}$ state lies below the first 4$^{+}$ state at maximum triaxiality. In contrast, Wilets and Jean proposed the gamma-unstable rotor model, which assumes no strict $\gamma$ confinement in the potential energy surface. More recently, a novel perspective on nuclear deformation was proposed using $^{166}$Er, suggesting that this nucleus does not exhibit axial symmetry but instead possesses triaxial deformation in its ground state. Furthermore, the $\gamma$-vibrational band was interpreted as rotational motion along an asymmetric axis. However, there is no definitive conclusion regarding axial versus triaxial deformation in deformed nuclei based on either experimental or theoretical results.

Neutron-rich Zr and Mo nuclides are promising candidates for investigating triaxiality due to their moderately deformed ground states. Recent measurements revealed that $^{110}$Zr, which lies at the $Z=40$ and $N=70$ shell closures of the harmonic oscillator potential, exhibits a well-deformed nature. Nonetheless, unresolved questions remain, such as the possibility of shape coexistence or triaxial deformation in this isotope, as predicted by different theoretical models. Additionally, theoretical studies suggest that Mo isotopes from $A=102$ to 110 may exhibit triaxiality. Notably, the second 2$^{+}$ states in these isotopes significantly drop in energy, falling below the first 4$^{+}$ states starting with $^{108}$Mo, a feature strongly tied to triaxial motion. However, debates on triaxiality persist due to differing interpretations of $\gamma$ vibration, the rigid triaxial rotor, and the $\gamma$-unstable rotor models. Consequently, more advanced experimental evidence, such as lifetime measurements for transition rates, is essential to determine the triaxial nature of these nuclides.

To address these questions, a high-resolution in-beam $\gamma$-ray spectroscopy study of nuclei near $^{110}$Zr was conducted as part of the HiCARI (High-resolution Cluster Array at RIBF) campaign at RIBF, aiming to measure level lifetimes. The HiCARI array consisted of several types of high-purity germanium detectors, including six Miniball triple clusters, four segmented Clover detectors, and two GRETINA-type tracking detectors. Through this experiment, $^{108}$Zr, $^{110}$Zr, $^{110}$Mo, and $^{112}$Mo were produced via nucleon-removal reactions of radioactive beams.

In this presentation, we will discuss the experimental results for $^{108}$Zr, $^{110}$Zr, $^{110}$Mo, and $^{112}$Mo. Lifetimes of excited states in these nuclei were analyzed using the line-shape method, and new level schemes were established. Advanced theoretical models were applied to interpret our experimental findings and to explore triaxiality in neutron-rich Zr and Mo isotopes.

Speaker: Dr Byul Moon (CENS, IBS)

Presentation_ID116_Moon.pdf

161 Multiple shape coexistence in 100Zr

A sudden onset of deformation is observed in the ground states of Zr and Sr appearing sharply at $N=60$ [1]. This unique feature will be discussed in the context of state-of-the-art Monte Carlo Shell Model (MCSM) calculations which were the first to successfully reproduce the rapid increase of collectivity and dramatic changes in the low-energy spectra of the Zr isotopes [2]. According to the MCSM calculations, an inversion of nearly-spherical and well-deformed configurations in $^{98}$Zr and $^{100}$Zr appears with small to no mixing, causing an abrupt ground-state shape transition. Furthermore, the presumably prolate ground state of $^{100}$Zr is predicted to coexist with multiple excited configurations possessing different intrinsic shapes.

The MCSM theoretical predictions were put to the test in a recent $\beta$-decay study of $^{100}$Zr performed at the TRIUMF ISAC I facility. A mixture of $^{100}$Rb and $^{100}$Sr ions was delivered onto a mylar tape in the center of the powerful GRIFFIN spectrometer [3], comprising $15$ large-volume HPGe clover detectors coupled to seven LaBr$_3$ detectors for fast-timing lifetime measurements. The collected $\gamma-\gamma$ coincidence data was used to substantially extend the level scheme of $^{100}$Zr and firmly assign the spins of key states via $\gamma-\gamma$ angular correlations. Those include several newly found $0^+$ states, some of which were recently reported in Ref. [4], and a potential candidate spin-2 member of a band built on the $0_4^+$ state [5].

Selected results will be presented, including the lifetime of the $2_2^+$ state, extracted for the first time in this work. The shape-coexistence scenario in $^{100}$Zr will be put on firm ground and striking structural similarities between $^{100}$Zr and $^{98}$Sr [6] will be revealed.

[1] P.E. Garrett et al., Prog. Part. Nucl. Phys. 124 (2022) 103931.
[2] T. Togashi et al., Phys. Rev. Lett. 117 (2016) 172502.
[3] A.B. Garnsworthy et al., NIM Phys. Res. A, 918 (2019).
[4] J. Wu et al., Phys. Rev. C 109, (2024) 024314.
[5] D. Kalaydjieva et al., Acta Phys. Pol. Proc. Supp. 16 (2023) 4-A15.
[6] E. Clément et al., Phys. Rev. Lett. 116 (2016) 022701.

Speaker: Dr Desislava Kalaydjieva (University of Guelph)

Presentation_ID201_Kalaydjieva_updated.pdf

162 Spectroscopy of shell-model nuclei around A = 90

Abstract

The investigation of nuclei in the mass-90 region provides insight into various aspects of both single-particle and collective excitations. Large-scale shell-model calculations have demonstrated good agreement with experimental data across both low- and high-spin states. High-spin states in the mass-90 region have been observed with multiquasiparticle configurations. The $g_{9/2}$ orbital plays a crucial role in generating both low- and high-spin states. The lower energy part of the level scheme is primarily dominated either by the excitation of $fp$ protons to the $g_{9/2}$ orbital or by proton occupancy in this orbital. In contrast, the high-spin states are mainly driven by the coupled excitation of ${\nu}g_{9/2}$, particularly to
${\nu}d_{5/2}$, along with proton excitation across the Z = 40 shell gap. In the N = 50 isotones— $^{86}$Kr, $^{87}$Rb, $^{88}$Sr, $^{89}$Y, $^{90}$Zr [1], $^{91}$Nb [2], $^{92}$Mo [3], $^{93}$Tc, $^{94}$Ru, and $^{95}$Rh—shell-model calculations have successfully explained neutron excitations from the $g_{9/2}$ orbital to $d_{5/2}$.

The odd-odd nuclei in the mass 90 region are equally interesting because both the odd nucleons span the same Z$\sim$40, N$\sim$50 subshell space, providing a good testing ground to study the role of proton-neutron residual interaction and its influence on both the single-particle as well as collective motion. The odd-odd nucleus $^{90}$Nb, with one proton particle and one neutron hole outside the Z = 40 and N = 50 shells, respectively, can provide us
valuable information about the particle-hole interaction at low as well as high-spin states. In-beam gamma-ray spectroscopy of $^{90}$Nb was carried out using fusion-evaporation reaction $^{65}$Cu($^{30}$Si, 3n2p) at a beam energy of 120 MeV [4]. The gamma rays were detected using the Indian National Gamma Array (INGA [5]) having sixteen Compton-suppressed HPGe clover detectors at the TIFR, Mumbai. In the present study, 15 new transitions were found. The positive parity sequence was modified based on triple gamma-ray coincidence conditions. We found an E3 transition decaying from 11$^-$ to the ground state, 8$^+$. However, the experimental B(E3) = 0.020(4) W.u. indicates that the 11$^-$ is not collective.

The odd-odd, odd-even, and even-even nuclei, $^{90}$Nb, $^{91}$Nb, and $^{92}$Mo, were studied in the framework of shell-model with GWBXG interaction. The deviations of shell-model calculation with the experimental data suggest the scope for improvement in the interaction.
The experimental results for $^{90}$Nb and the shell model comparison for $^{90}$Nb, $^{91}$Nb, and $^{92}$Mo will be presented.

Acknowledgment
This work is supported by the Department of Atomic Energy, Government of India (Project Identification No. RTI 4002); the Department of
Science and Technology, Government of India (Grant No. IR/S2/PF-03/2003-II); and the U. S. National Science Foundation (Grant No. PHY-2310059).

References
[1] P. Dey et al., PRC 105, 044307 (2022).
[2] P. Dey et al., PRC 109, 034313 (2024).
[3] Vishal Malik et al., JPhysG accepted.
[4] Vishal Malik et al., under review.
[5] R. Palit et al., NIM A 680, 90 (2012).

Speaker: vishal malik (Tata Institute of fundamental research, Mumbai)

Presentation_190_Malik.pptx

Parallel Session: 3_Nuclear Structure (2)

Convener: Sebastian Raeder (GSI Helmholtzzentrum für Schwerionenforschung GmbH)

163 Origin of the Low-energy Enhancement in the γ-Strength Function

The γ-strength function, as a function of the γ-ray energy, is a statistical measure of the probability of hot nuclei in the quasi-continuum to deexcite through emitting γ-rays. The γ-strength function is crucial in the (n,γ) cross sections, and is therefore related to the neutron capture processes in nucleosynthesis. The low-energy enhancement, which is a sharp spike of the γ-strength function at zero γ-ray energy, is being discovered in more and more nuclei in recent years. It has been demonstrated to has a large effect on the rapid neutron capture process (the r-process), and was believed to relate to the nuclear scissors motion. However, the origin of such an enhancement is not yet understood. In this talk the origin of the low-energy enhancement is discussed from a collective point of view, with the collective degree of freedom in the scissors motion considered. It is found that the low-energy enhancement arises from the scissors motion in the weakly deformed limit. In this case the scissors motion becomes approximately free, which is called "scissors rotation" in order to distinguish from the well-known scissors vibration.

Speaker: Fang-Qi Chen (Lanzhou University)

Presentation_ID391_Chen.pptx

164 ΔI = 2 Bifurcation as a Characteristic Feature of Scissors Rotational Bands

The M1 scissors mode in deformed atomic nuclei depicts the collective vibration of the proton and neutron systems with respect to each other. There have been suggestions that the M1 scissors mode may explain discrepancies between theoretical calculations using the Hauser-Feshbach theory and evaluated data of radiative neutron captures for many applications ranging from nuclear technology to nuclear astrophysics. In a recent Letter [Phys. Rev. Lett. 129, 042502 (2022)], we reported microscopic many-body calculations indicating that rotational bands based on scissors vibrations exhibit systematic splitting between neighboring spin states (ΔI = 2 bifurcation) in which the magnitude of the moment of inertia oscillates between states having even and odd spins. We showed that this unexpected result is caused by self-organization of the deformed proton and neutron bodies in the scissors motion, which is further amplified by the Kπ=1+ two-quasiparticle configurations near the scissors states. We proposed that the puzzling excited state found above the 1+ scissors state in 156Gd [Phys. Rev. Lett. 118, 212502 (2017)] is the first evidence of this effect, and predicted that bifurcation may generally appear in all other scissors rotational bands of deformed nuclei, and possibly in other systems exhibiting collective scissors vibrations. In order to confirm the bifurcation feature, it is crucial to identify experimentally the excited states with Iπ ≥ 3+ in the scissors rotational bands.

Speaker: Dr Cuijuan Lv (Shanghai Jiao Tong University)

Presentation_ID394_Lv.pdf

165 Probing the evolution of transitional structure in 158Er via β-decay of Tm isotope

Nuclei around the rare earth transitional region (N ~ 90) present a variety of interesting nuclear features ranging from triaxiality, octupoles and shape coexistence. The proton rich nucleus 158Er (N = 90) lies at the boundary of the phase-transitional region, hence, it is likely to display of both transitional and deformed characteristics [1]. Properties of the low-lying states play a vital role in probing the structure of nuclei. However, the interpretation of the structure of the low-lying states in the rare earth, N ~ 90 region from previous studies was predominantly based on level spacing [1-5]. Although, it has been shown that energy spacings alone can be misleading [6]. Therefore, it has become evident that a larger set of precise experimental data for a variety of model-independent observables is necessary to constrain the interpretation of these excitations [7].
We shall report on the internal conversion coefficients, branching, and mixing ratios deduced from γ-e-, γ-γ coincident and, γ-γ angular correlation measurements following the β-decay of 158Tm using the GRIFFIN set up with its arsenal of ancillary detectors.

Speaker: Dr Abraham Avaa (TRIUMF)

Presentation_268_Avaa.pdf

166 New region of maximum octupole collectivity in the rare-earth nuclei: the case of Gd isotopes

We present the first evidence of maximum octupole collectivity in the Gd isotopic chain through a direct measurement of an enhanced B(E3) value in 150Gd. This result was achieved via two highly sensitive experiments designed to determine the lifetime of the first 3− state and the weak E3 decay branch to the ground state. With a measured B(E3) strength of 45(5) W.u., this value ranks among the highest and the most precise recorded in this region, comparable in strength to those observed in neutron-rich Ba nuclei, a region traditionally known for its enhanced octupole collectivity. We compare the available experimental results for the E3 strengths in the Gd isotopic chain with five state-of-the-art theoretical models: the quasi-particle random phase approximation (QRPA), the time-dependent Hartree-Fock (TDHF), the quadrupole-octupole collective Hamiltonian (QOCH), the mean-field mapped interacting boson model (m-IBM), and the triaxial projected shell model (TPSM). We conclude that the QRPA provides a strong explanation for the increasing trend of B(E3) values in Gd nuclei with N=82–86.

Speaker: Sorin Pascu (IFIN-HH)

Presentation_ID426_Pascu.pptx

167 High resolution laser spectroscopy for the study of exotic nuclei

Study of the properties and structure of exotic nuclei far from stability is a key area of research in modern nuclear physics [1]. High resolution laser spectroscopy is one of the powerful experimental tools for investigating the nuclear properties of exotic nuclei [2], such as the nuclear spins, electromagnetic moments and charge radii. These properties of unstable nuclei continue to deepen our understanding of exotic nuclear structure and to provide a prominent test for nuclear many-body methods and nuclear interactions [3-4].

In this contribution, recent results on the nuclear properties of several isotopic chains (e.g. Sc and Zn) in the calcium and nickel mass regions will be presented, along with their interpretation in the context of nuclear structure.

[1] Y.L. Ye et al., Nature Reviews Physics (2024) ,10.1038/s42254-024-00782-5
[2] X.F. Yang et al., Prog. Part. Nucl. Phys. 129, 104005 (2023).
[3] A. Koszorus et al., Nature Physics, 17, 439 (2021).
[4] S.W. Bai et al., Physics Letters B 829, 137064 (2022).

Speaker: Prof. Xiaofei Yang (Peking University)

Presentation_ID279_Yang-pdf.pdf

Parallel Session: 3_Nuclear Structure (3)

Convener: Andreas Görgen (University of Oslo)

168 Structural evolution of neutron-rich calcium isotopes

The calcium isotopes are the ideal system to investigate the evolution of shell structure and magic numbers due to the closed proton shell with Z=20. The first experimental evidence of the N=34 sub-shell closure was found in 54Ca at RIKEN [1]. To study the magicity of N=34 and nuclear structure towards N=60, several in-beam gamma-ray spectroscopy measurements with proton-induced nucleon knockout reactions at around 200 MeV/u were performed at RIBF RIKEN, with the use of MINOS liquid hydrogen target device coupled with DALI2 gamma spectrometer. Exclusive cross sections and parallel momentum distributions were obtained. In 54Ca(p,pn)53Ca, a significantly larger cross section to the p3/2 state compared to the f5/2 state was observed in the excitation of 53Ca, providing direct evidence for the nature of the N=34 shell closure [2]. Gamma decays were observed in 56Ca and 58Ca following the quasi-free one-proton knockout reactions from 57,59Sc beams. The first 2+ excitation energies of 56Ca and 58Ca, combined with shell model calculations, preclude the possibility for a doubly magic 60Ca and potentially drive the dripline of Ca isotopes to 70Ca or even beyond [3]. Moreover, the structures of deeply bound nucleons in 53Ca and 55Ca populated from 54,56Ca(𝑝,𝑝𝑛) reactions were also probed for the first time. The observed excitation energies and cross-sections in the resonance states of 53Ca and 55Ca point towards extremely localized and well separated strength distributions in 53Ca and 55Ca. The extracted shell gap of approximately 3 MeV between the f7∕2 and p3∕2 orbitals indicates the robustness of the N=28 shell closure, even with the deeply bound f7∕2 orbital [4]. In this talk, the experiment results and the state-of-the-art theoretical calculations will be presented.

References:
[1] D. Steppenbeck et al., Nature, 502, 207 (2013).
[2] S. Chen, J. Lee, P. Doornenbal et al., Phys. Rev. Lett 123, 142501 (2019).
[3] S. Chen, F. Browne, P. Doornenbal, J. Lee et al., Phys. Lett B 843, 138025 (2023).
[4] P.J. Li, J. Lee, P. Doornenbal, S. Chen et al., Phys. Lett. B 855, 138828 (2024).

Speaker: Jenny Lee (The University of Hong Kong)

Presentation_ID107-Lee.pdf

169 Excited States Lifetime measurements in neutron-rich Ca, Ar isotopes: impact on the shell evolution along N=28 and Z=20

**

Excited States Lifetime measurements in neutron-rich Ca, Ar isotopes: impact on the shell evolution along N=28 and Z=20

**

A. Gottardo$^1$, G. Andreetta$^1$, C. Fransen$^2$, D. Mengoni$^3$, J.J. Valiente-Dobon$^1$
$^1$ INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy
$^2$ University of Cologne, Cologne, Germany
$^3$ INFN and University of Padova, Padova, Italy

and the AGATA collaboration

The region around doubly magic $^{48}$Ca is a cornerstone of our understanding of nuclear structure, characterized by the appearance of subshell closures at N=32 and 34 [1], and by the gradual disappearance of N=28 shell closure below Z=20 [2]. However, several experimental findings have challenged this understanding. Large charge and matter radii were found in $^{51-52}$Ca [3,4], showing insensitivity to the N=32,34 subshell closures. The long-standing conundrum of the small B(E2) value in $^{46}$Ar [5,6] has recently been attributed to a new proton sub-shell closure at Z=18 in $^{46}$Ar [7].
We measured lifetimes of excited levels in $^{50-(52)}$Ca and $^{46-(48)}$Ar isotopes (and other nearby nuclei) produced in a multi-nucleon transfer reaction at the Legnaro Laboratories. A beam of 48Ca at 300 MeV impinged on a $^{238}$U target and the target-like recoils were identified event-by-event in mass and atomic number by the mass spectrometer PRISMA [8]. Gamma rays were measured in coincidence with reaction recoil with the AGATA $\gamma$-ray tracking array [9]. Lifetimes were measured using the recoil differential Doppler shift method by mounting the uranium target on a plunger device. Shorter lifetimes were probed using the differential Doppler shift attenuation technique, using a $^{238}$U target with a thick niobium backing. Thanks to the cutting-edge AGATA resolving power, the lifetimes of several yrast and yrare states with spin ≤ 4 were measured.
We will present preliminary results concerning the lifetimes of excited states in $^{46}$Ar and ${50}$Ca, comparing them with shell-model calculations with the interactions available in this region, also including three-body effects. We will discuss the measurement impact on the neutron $f_{5/2}$ shell evolution towards N=34 as well as on the proposed proton subshell closure in $^{46}$Ar [7]. We will also discuss possible fingerprints of the large neutron $p_{3/2}$ shell radius [10] in $\gamma$-ray spectroscopy.

[1] D. Steppenbeck et al., Nat. 502, 207–210 (2013)
[2] T. Glasmacher et al. Phys. Lett. B, 395, 163 (1997)
[3] R. F. Garcia Ruiz et al., Nat. Phys. 12, 594 (2016)
[4] M. Tanaka et al., Phys. Rev. Lett. 124, 102501 (2020)
[5] A. Gade et al., Phys. Rev C 68, 014302 (2003)
[6] S. Calinescu et al., Phys. Rev. C 93, 044333 (2016)
[7] D. Brugnara et al., submitted
[8] A. Stefanini, et al. Nuc. Phys. A, 701, 217 (2002)
[9] S. Akkoyun et al, NIM A 668, 26 (2012)
[10] M. Enciu, Phys. Rev. Lett. 129, 262501 (2022)

Speaker: Andrea Gottardo (INFN, Laboratori Nazionali di Legnaro)

Presentation_ID221_Gottardo.pdf

Presentation_ID221_Gottardo.pptx

170 Isospin Symmetry: nuclear charge radii and low-ℓ orbits

The role of low-ℓ orbits is particularly important in determining nuclear properties such as the nuclear radius. This is reflected into mirror energy differences that have been studied systematically in the sd- and fp-shells using existing data as well as new measurements for T=1/2 and T=3/2 mirror nuclei. Low-ℓ orbits contribute differently to mirror energy differences depending on their occupation numbers. Such effect has been explained considering that the addition of a nucleon induces opposite changes in the potential wells of protons and neutrons and that tends to equalize proton and neutron radii [1]. This agrees with recent experimental results [2] and results in a unified description of nuclear charge radii deduced from mirror energy differences and nuclear charge radii measured directly in experiment.

References
[1] J. Bonnard, S.M. Lenzi, and A. P. Zuker, Physical Review Letters 116 (2016) 212501
[2] M. Enciu, et al. Physical Review Letters, 129 (2022) 262501

Speaker: Francesco Recchia (University and INFN Padova)

Presentation_ID430_Recchia.pptx

171 Quadrupole collectivity and shape coexistence around $^{60}$Ca

Recent spectroscopic measurements in neutron-rich $N=40$ nuclei towards $^{60}$Ca give an insight into shell structure in this region [1]. Large-scale shell model calculations [2] predicted a sizable collectivity in $^{60}$Ca and the island of inversion extended to $^{60}$Ca.
In this contribution, we will present the results of low-lying states in $N=40$ nuclei by employing the five-dimensional collective Hamiltonian (5DCH) method based on the Skyrme energy density functional. The 5DCH method explicitly treats quadrupole degrees of freedom for rotation and vibration. We use the local quasiparticle random phase approximation to include important dynamical correlations to the inertial functions in the kinetic energies that have been ignored in most of the previous related works [3]. The present calculation reproduces the experimental $2_1^+$ energy and $B(E2;2_1^+ \to 0_1^+)$ values. In particular, we discuss the property of the low-lying excited $0^+$ state and low $R_{0/2}=E(0_2^+)/E(2_1^+)$ ratio obtained in $^{60}$Ca, which indicates shape coexistence.
[1] M. L. Cortes et al., Phys. Lett. B 800, 135071 (2020).
[2] S. M. Lenzi, F. Nowacki, A. Poves, and K. Sieja, Phys. Rev. C 82, 054301 (2010).
[3] K. Washiyama, N. Hinohara, and T. Nakatsukasa, Phys. Rev. C 109, L051301 (2024).

Speaker: Kouhei Washiyama (University of Tsukuba)

Presentation_ID611_Washiyama.pptx

172 Imaging shapes of atomic nuclei in high-energy nuclear collisions from STAR experiment

High-energy nuclear collisions have been recently proposed as a powerful tool to image the global structure of heavy atomic nuclei. We present the first quantitative demonstration of this method by extracting the quadruple deformation $\beta_2$ and triaxiality $\gamma$ for $^{238}$U nuclei, known for its large prolate shape. We achieve this by comparing several collective flow observables in collisions of $^{238}$U with collisions of near-spherical $^{197}$Au. Though the extracted $\beta_{2}$ of $^{238}$U is consistent with low-energy experiments, the measurements indicate a small deviation from axial symmetry with non-zero $\gamma$ value in their nuclear ground state [1]. A similar comparative measurement is carried out in collisions of $^{96}$Ru and $^{96}$Zr. Large differences are observed in almost all flow observables in the two collision systems, reflecting strong impacts from the structure differences between the pair of isobars. In particular, our measurements suggest an intriguing octupole deformation $\beta_3$ in $^{96}$Zr which is not predicted by mean field model calculations, as well as a larger neutron skin in $^{96}$Zr. The prospect of such an imaging method for studying light ion $^{16}$O structure compared to the state-of-the-art $ab$ $initio$ calculations is also explored. Our work introduces a novel approach for imaging nuclear shapes, enhances our understanding of quark gluon plasma initial conditions, and sheds light on nuclear structure across different energy scales.

[1] STAR Collaboration, Nature 635, 67-72 (2024)

Speakers: Chunjian Zhang (Fudan University (CN)), Prof. Chunjian Zhang (Fudan University)

Presentation_ID90_Zhang.pdf

Parallel Session: 3_Nuclear Structure (4)

Convener: Kathrin Wimmer (GSI)

173 Improving nuclear Density Functional Theory: different paths

In this contribution, I will present a short, personal overview of nuclear Density Functional Theory (DFT). Compared to so-called ab initio approaches, DFT is more phenomenological; however, it can be applied throughout the whole isotope chart and used not only to predict ground-state properties, like masses, radii, or intrinsic deformations but also for nuclear spectroscopy. The use of DFT for excited states, like Giant Resonances, will be emphasised. Monopole resonances and dipole resonances will be discussed. The possibility of exciting some resonances exclusively using vortex photons will be mentioned.
Still, several ways to parameterise an Energy Density Functional (EDF) exist, and the path towards a “universal” EDF looks unclear. I will discuss some Bayesian inferences of EDF parameters that may lead to more “agnostic” EDFs. Then, I will advocate the need to ground DFT on ab initio as has been done for Coulomb systems and discuss the status and perspectives for this challenging task. Finally, I will touch upon the relationship between DFT and many-body approaches.

Speaker: Gianluca Colò (University of Milano and INFN)

Presentation_ID655_Colo.pptx

174 Constraints on neutron skin thickness and symmetry energy

The structure of exotic neutron-rich nuclei is one of the main science drivers in contemporary nuclear physics research [1]. The new measurements of pygmy dipole (PDR) and giant dipole (GDR) resonances in neutron-rich nuclei have sparked advancements in nuclear models. The quasiparticle random phase approximation, utilizing the self-consistent mean-field derived from Skyrme effective interactions, is a widely used tool for describing the PDR and GDR. This approach made it possible to a successful description of the properties of low-lying states and the characteristics of giant multipole resonances in spherical nuclei [2,3].

Due to the anharmonicity of vibrations there is a coupling between simple particle-hole configurations and more complex states [4,5]. As an illustration, we study the properties of the low-lying dipole states in the neutron-rich Ca and Ni isotopes [6,7]. This reveals a number of characteristic features of the low-energy E1 modes. The effect of the low-energy E1 strength on the electric dipole polarizability is discussed [5]. The correlations between the electric dipole polarizability, the symmetry energy, and neutron skin thickness are studied [8].

The research was supported within the framework of the scientific program of the National Center for Physics and Mathematics, topic no. 6 “Nuclear and Radiation Physics” (stage 2023-2025).

[1] A. Zilges, D.L. Balabanski, J. Isaak, and N. Pietralla, Prog. Part. Nucl. Phys. 122, 103903 (2022).
[2] N. Paar, D. Vretenar, E. Khan, and G. Colò, Rep. Progr. Phys. 70, 691 (2007).
[3] E.G. Lanza, L. Pellegri, A. Vitturi, and M.V. Andrés, Prog. Part. Nucl. Phys. 129, 104006 (2023).
[4] V.G. Soloviev, Theory of Atomic Nuclei: Quasiparticles and Phonons. Bristol/Philadelphia 1992.
[5] A.P. Severyukhin, N.N. Arsenyev, and N. Pietralla, Phys. Rev. C. 104, 024310 (2021).
[6] N.N. Arsenyev, A.P. Severyukhin, V.V. Voronov, and N.V. Giai, Phys. Rev. C. 95, 054312 (2017).
[7] N.N. Arsenyev, A.P. Severyukhin, V.V. Voronov, and N.V. Giai, Phys. Part. Nucl. 50, 528 (2019).
[8] N.N. Arsenyev, and A.P. Severyukhin, Moscow Univ. Phys. Bull. 79, 200 (2024).

Speaker: Dr Nikolay Arsenyev (Joint Institute for Nuclear Research, Dubna¸ Russian Federation)

Presentation_id127_Arsenyev.pdf

175 Systematic Study on Interaction Cross Sections and Neutron Skin Thickness for Ni Isotopes

Since nuclear matter is composed of two Fermi particles, protons and neutrons, the equation of state(EOS) of nuclear matter has a term that depends on the density difference between the two, which is called the symmetry energy. From previous studies, it is known that the first-order density dependence of the symmetry energy $L$ is closely related to the thickness of the neutron skin $r_{\rm np}$ [1].

In this study, interaction cross sections ${\sigma}_{\rm{I}}$ for $^{58-77}$Ni on a carbon target at 250 MeV/nucleon have been measured to derive matter radii. Recently, the charge radii of Ni isotopes up to mass number 70 were measured by isotope shift method [2]. So, we can derive the neutron skin thickness $r_{\rm np}$ in the region of $A$ = 58 to 70. The experiment was performed at the Radioactive Isotope Beam Factory(RIBF) at RIKEN by using the BigRIPS fragment separator.

In this presentation, we’ll report the matter radii derived from the experimental cross sections using Glauber calculations, and neutron skin thickness obtained by combining the matter radii derived in the present study with the charge radii already known from previous research. Using several methods, the $L$ parameter of the equation of state (EOS) was derived from the slope of the neutron skin thickness with respect to $\delta = (N-Z)/A$. As a result, when using mean-field calculations[3,4], $L$ = 81(63) MeV, and when using the droplet model[5,6], $L$ = 151(27) MeV. These values are somewhat larger than the previous averaged value, while these are consistent within the error range with $L$ = 106(37) MeV obtained from PREX[7].

Speaker: Miki Fukutome (Osaka University)

Presentation_ID639_Fukutome.pptx

176 Neutron-rich nuclei and neutron skins from chiral low-resolution interactions

Neutron-rich nuclei provide important insights to nuclear forces and to the nuclear equation of state. Advances in ab initio methods combined with new opportunities with rare isotope beams enable unique explorations of their properties based on nuclear forces applicable over the entire nuclear chart. In this talk, I will present recently-introduced chiral low-resolution interactions that accurately describe bulk properties from $^{16}$O to $^{208}$Pb. With these, we investigated density distributions and neutron skins of neutron-rich nuclei. Our results show that neutron skins are narrowly predicted over all nuclei with interesting sensitivities for the most extreme, experimentally unexplored cases.

Speaker: Pierre Arthuis (IJCLab Orsay, CNRS, France)

Presentation_ID22_Arthuis.pdf

177 ab initio effective operator with continuum

Nuclei in the vicinity of driplines have been receiving a lot of attention in nuclear structure studies. Continuum coupling plays a pivotal role in accurately describing weakly bound and unbound phenomena in these nuclei. To calculate observables of the nuclei as open quantum systems, we have developed valence-space effective operators in the complex-energy Berggren basis using many-body perturbation theory. We focus on the Gamow-Teller $\beta$ decay in the $sd$ shell. The two- plus three-nucleon force from the chiral effective field theory, named EM1.8/2.0, has been used. The Gamow shell model which takes the continuum coupling into account can properly reproduce experimental observations of weakly bound and unbound states. The $\beta$-decay isospin asymmetry between the dripline nucleus $^{22}$Si and its mirror partner $^{22}$O is reproduced, in which the $s_{1/2}$ continuum plays a key role. Significant Thomas-Ehrman shift is seen through mirror energy differences between the mirror daughters $^{22}$Al and $^{22}$F, in which the continuum effect plays an important role.

Speaker: Zhi-Cheng Xu (Fudan University)

Presentation_ID_108_Xu.pdf

Presentation_ID_108_Xu.pptx

178 Does Effective Field Theory Yield Model Independent Predictions in Nuclear Systems?

Following the suggestion of Weinberg, it is widely believed that chiral effective field theory eliminates the model dependence of theoretical predictions in nuclear systems. We explain why this is not necessarily so.

Speaker: ANTHONY THOMAS (University of Adelaide)

Presentation_ID482_Thomas.pdf

179 Nuclear Lattice EFT Simulation with Woods-Saxon Potentials

The experimental exploration of the neutron dripline is challenging. Currently, neon is the heaviest nucleus for which the neutron dripline has been measured experimentally. Predictions for the neutron dripline of nuclei heavier than neon largely rely on theoretical models. However, these predictions are often highly model-dependent. Nuclear Lattice Effective Field Theory is an ab initio approach used to explore quantum many-body systems. In this talk, we will discuss the nuclear properties of oxygen isotopes near the neutron dripline, using the Woods-Saxon potential in Nuclear Lattice Effective Field Theory.

Speaker: Myungkuk Kim (CENS/IBS)

Presentation_ID501_KIM.pdf

10:30 Break

Parallel Session: 4_Applications Based on Nuclear Physics

Convener: Thomas Elias Cocolios (KU Leuven, IKS)

180 The solid state Physics programme at ISOLDE-CERN: materials for the society

An important scientific challenge to obtain renewable energy-harvesting solutions for a sustainable future requires the investigation of materials functionalities down to the atomic scale. ISOLDE-CERN is the worldwide reference facility for the production and delivery of radioactive ion beams of high purity. The produced beam is dedicated to many different purposes for, e.g., atomic and nuclear physics, astrophysics, material science, biophysics, and medical research. Since the late 70s the laboratory is pioneer in the use of nuclear techniques for studying local properties of materials using high-technology equipment [1]. For instance, the brand-new ultra-high-vacuum implantation chamber called ASPIC’s Ion Implantation chamber (ASCII) [2] decelerates the radioactive ion beam delivered at ISOLDE-CERN allowing to perform ultra-low energy ion implantations, and local measurements on the surface and interface of materials. The new MULTIPAC setup for Perturbed Angular Correlation Experiments in Multiferroic (and Magnetic) Materials [3] consists of a unique cryogenic magnetic system that simultaneously allows to measure local magnetic and ferroelectric properties of materials in magnetic fields up to 8.5 T. Last, but not least, the eMIL-Setup [4] is an advanced emission Mössbauer spectrometer for measurements in versatile conditions of several classes of materials, thanks to the emission Magnetic Mössbauer Analyzer (eMMA) extension [5]. This presentation introduces the new setups as powerful tools and discuss the possibilities of investigations on the frontiers of solid-state physics research [5] with green materials.
[1] https://doi.org/10.1088/1361-6471/aa81ac
[2] https://doi.org/10.3390/cryst12050626
[3] https://cds.cern.ch/record/2845935/files/INTC-I-249.pdf
[4] https://doi.org/10.1016/j.nima.2020.163973
[5] http://cds.cern.ch/record/2705975/files/INTC-I-211.pdf

Speaker: Juliana Schell (ISOLDE-CERN, Universität Duisburg-Essen)

SSP_INPC2025_ID693_Schell.pptx

181 Excitation of Thorium-229 doped in crystals using a pulsed laser toward nuclear clocks

$^{229}$Th has the uniquely low nuclear first excited state ($^{229m}$Th) with the excitation energy of 8.356 eV.
This allows excitation using vacuum ultraviolet lasers, which opens up the possibility of realizing a clock based on nuclear energy levels, called nuclear clocks.
It has long been known that $^{229}$Th has a first excited state with low excitation energy, but laser excitation has been difficult to achieve.
However, in 2024, the world's first laser excitation of $^{229}$Th was finally achieved using $^{229}$Th-doped CaF$_2$ [1].
Following this, two other groups also reported laser excitations, leading to rapid advances in research on $^{229}$Th [2][3].

Our group has conducted experiments using the high-intensity synchrotron radiation facility, SPring-8, in Japan, to excite $^{229}$Th to $^{229m}$Th via its second excited state and observe the de-excitation light from $^{229m}$Th using $^{229}$Th-doped CaF$_2$[4].
For this experiment, we have developed a detector system that can efficiently reduce background events and that can also be used for laser excitation experiments [5].
Recently, we have developed a vacuum ultraviolet pulsed laser in our laboratory and have initiated laser excitation experiments.
In this presentation, we will introduce an overview of our laser and detection systems and the status of our laser excitation experiments.

[1] J. Tiedau et al., Phys. Rev. Lett. 132, 182501 (2024)
[2] R. Elwell et al., Phys. Rev. Lett. 133, 013201 (2024)
[3] C. Zhang et al., Nature 633, 63 (2024)
[4] T. Hiraki et al., Nat. Commun. 15, 5536 (2024)
[5] T. Hiraki et al., hyperfine interactions, 245, 14 (2024)

Speaker: Dr Takahiro Hiraki (Okayama University)

Presentation_ID18_Hiraki.pdf

182 The controlling of the Thorium-229 isomer states in CaF$_2$ crystal.

Thorium-229 possesses an exceptionally low-energy isomeric state (~8.356 eV, $^{229m}$Th), which can be excited using the state-of-the-art tabletop lasers operating in the vacuum ultraviolet (VUV) region [1–3]. The transition from the ground state to $^{229m}$Th is considered a clock transition, offering the potential for a nuclear clock that could surpass current optical atomic clocks in robustness and performance. Such a nuclear clock could be the next-generation platform for probing new physics beyond the Standard Model. To study this charming transition, we utilized the high-brilliance synchrotron radiation at SPring-8 (Hyogo, Japan) and developed an experimental setup capable of manipulating the three lowest nuclear states of thorium-229 when they are doped into a CaF$_2$ crystalline lattice [4]. Our experiment reveals that the lifetime of $^{229m}$Th in the CaF$_2$ crystal could be shortened by X-ray irradiation, and we called this phenomenon the ``isomer quenching'' [5]. In this presentation, we will introduce our new findings, demonstrating that crystal temperature significantly affects the efficiency of isomer quenching. Additionally, observations of the isomer yield and crystal luminescence suggest a possible interaction process between the thorium nucleus and the crystal environment.

Speaker: Ming Guan (Okayama University)

INPC2025 GM_#391_Guan.pdf

Parallel Session: 4_Fundamental Symmetries and Interactions in Nuclei

Convener: Sunji KIM (Institute for Basic Science)

183 Nuclear Charge Radius Measurement for Neutron-deficient Na Isotopes

We report on precision measurement of the isotope shifts of neutron-deficient sodium isotopes to determine their nuclear charge radii, with a specific emphasis on $^{21}$Na. Precise determination of the nuclear charge radius allows for accurate calculation of the charge radius difference, ΔR$_{c}$, between $^{21}$Na and its mirror nucleus $^{21}$Ne. This difference provides critical constraints on the nuclear symmetry energy slope, L, and is also correlated with a correction term of the Ft value essential to the unitarity test of the Cabibbo-Kobayashi-Maskawa (CKM) matrix.
We conducted collinear laser spectroscopy (CLS) measurements at the RAON facility using the CLaSsy setup. $^{21}$Na was produced at the ISOL facility using a 70 MeV proton beam from a cyclotron impinging on the SiC target. The $^{21}$Na beam was accelerated to 20 keV and delivered to the CLaSsy beamline as a 10 Hz bunched beam through the Radio Frequency Quadrupole-Cooler Buncher (RFQ-CB). The bunched $^{21}$Na ion beam was neutralized in a charge exchange cell and subsequently interacted with a 589-nm laser beam. Fluorescence light from the D$_{1}$ transition line of $^{21}$Na was detected using a photomultiplier tube (PMT), and its hyperfine spectra were obtained by scanning the voltage applied to the ion beam. Data acquisition was synchronized with the bunched beam to enhance the signal-to-background ratio. Both collinear and anti-collinear methods were employed to enhance ion kinetic energy precision. From these measurements, we achieved improved precision of isotope shifts of $^{21}$Na in determining its nuclear charge radius. This study can be extended to perform precise measurements of nuclear symmetry energy and conduct unitarity tests of the CKM matrix for other isotopes with similar masses.

Speaker: Junho Won (CENS, IBS)

2025 INPC_20250522_Won.pptx

184 SALER@FRIB: Status of a New Search for BSM Physics Using Rare Isotopes

The Superconducting Array for Low Energy Radiation (SALER) at the Facility for Rare Isotope Beams (FRIB) is a new experiment using superconducting tunnel junction (STJ) radiation detectors implanted on-line with rare isotopes to search for physics beyond the Standard Model, initially targeting scalar and tensor current contributions to the weak force. We accomplish this by directly measuring the nuclear recoil spectra of implanted nuclei to ~1 eV precision, starting with the mirror nuclei $^{11}$C and $^{19}$Ne. In these cases, the recoil encodes information about the ratio between Fermi and Gamow-Teller decay modes allowing for an indirect measurement of $V_{ud}$.

Last year, we took delivery of SALER's adiabatic demagnetization refrigerator, STJ control and readout electronics, and 32 of the eventual 128 STJ sensors. We present on the status of initial offline testing of SALER at FRIB using a $^{137}$Cs source, development of a laser feedthrough and x-ray tube for calibration, and progress towards integration with existing systems at FRIB.

Acknowledgements:
This work is supported by the DOE-SC Office of Nuclear Physics, the Gordon and Betty Moore Foundation, and the Facility for Rare Isotope Beams.

Speaker: Andrew Marino (Colorado School of Mines)

Presentation_ID107_Marino.pptx

185 Precision Measurements of Mixed Mirror Transitions for St. Benedict

Precision beta-decay measurements offer unique insight into the electroweak part of the Standard Model through a variety of tests including the unitarity of the Cabbibo-Kobayashi-Maskawa (CKM) quark mixing matrix. A reliable unitarity test of the CKM matrix requires a precise and accurate value of $V_{ud}$. Several experimental quantities enter into the determination of $V_{ud}$ from superallowed mixed mirror decays including the half-life and the Fermi to Gamow-Teller mixing ratio, $\rho$. As such a precision half-life campaign has been running at the Nuclear Science Laboratory (NSL) at the University of Notre Dame which has measured the most precise half-life for several isotopes including, most recently, $^{28}$Al and $^{33}$Cl. In addition, the Superallowed Transition BEta- NEutrino Decay Ion Coincidence Trap (St. Benedict) is currently being commissioned at the NSL which aims to measure the beta-neutrino angular correlation parameter in order to extract $\rho$ from more of these transitions. Results from the most recent half-life measurements, as well as the first delivery of radioactive ion beams to St. Benedict, will be presented. This work is supported by the US National Science Foundation under grant numbers PHY-1725711, 2310059, and the University of Notre Dame.

Speaker: Regan Zite (University of Notre Dame)

Presentation_ID622_Zite.pdf

186 10C Superallowed Beta Decay Measurement with AGATA: CKM Matrix Unitarity Test

The CKM matrix, associated with quark mixing, is expected to be unitary within the framework of the Standard Model. Violation of the unitarity for the CKM matrix would provide a hint such as the existence of fourth-generation quarks [1] or leptoquarks [2,3]. In other words, precise test for the CKM matrix unitarity is one of the precision frontiers in the search for physics beyond the Standard Model. The square sum of the first column elements of the CKM matrix, $|V_{ud} |^2+|V_{us} |^2+ |V_{ub} |^2$, is a good probe for the unitarity test. Vud dominates the square sum, and it can be precisely measured by superallowed beta decay. Recently, theoretical uncertainty in the Vud has been reduced [4], providing motivation to further improve from the experimental side. Half-life, Q value, and decay branching ratio directly determine the $V_{ud}$, and for $^{10}$C superallowed beta decay, the branching ratio dominates the experimental uncertainty [5]. $^{10}$C is also important for the Fierz interference term search since $^{10}$C is the lightest nuclei exploited for superallowed beta decay measurements. We performed a new experiment aimed at reducing the uncertainty in the $^{10}$C branching ratio. Moreover, the half-life of the $^{10}$C superallowed beta decay can be obtained simultaneously from the experiment.

In the experiment, we used (p,n) and (p,p’) reactions between 10-MeV proton beam accelerated from the INFN-LNL Tandem and a 1-mg/cm$^{2}$ thick $^{10}$B target. The AGATA HPGe tracking array was employed to measure the gamma rays from the reactions, and it was the first AGATA experiment for fundamental symmetries. As a preliminary result, we got the half-life for the $^{10}$C superallowed beta decay, which shows consistency with the reference value. Thus far, no significant systematic uncertainties have been identified for the half-life; however, a detailed analysis of a potential systematic effect is ongoing. Additionally, the analysis of the branching ratio is also in progress. We will introduce the experimental setup and current status of the analysis in this presentation.

References:
[1] B. Belfatto, R. Beradze and Z. Berezhiani, Eur. Phys. J. C 80, 149 (2020).
[2] J. C. Pati and A. Salam, Phys. Rev. D 10, 275 (1974).
[3] P. Herczeg, Prog. Part. Nucl. Phys. 46, 413 (2001).
[4] C.-Y. Seng, M. Gorchtein and M. J. Ramsey-Musolf. Phys. Rev. D 100, 013001 (2019)
[5] J. C. Hardy and I. S. Towner, Phys. Rev. C 102, 045501 (2020).

Speaker: Yonghyun SON (Seoul National University)

INPC2025_Son_10C.pptx

187 Precise determination of the muon magnetic anomaly by the "Muon g-2" experiment at Fermilab

The Muon g-2 Experiment at the Fermi National Accelerator Laboratory has
published in 2023 its measurement of the muon magnetic anomaly, a_mu,
from data collected in 2018-2020, and it is about to release the final
result with the full statistics collected in 2018-2023. The published
result achieved a precision of 220 parts per billion (ppb) and it is
about to be improved by almost a factor of 2 in the final release,
providing a stringent test of the Standard Model. The tension with the
current theoretical full calculation, published in Summer 2020, is now
larger that 5 sigma, however a new approach based on lattice QCD points
to a hadronic contribution to a_mu larger than what previously expected
using e+e- data, and which will move the theoretical prediction closer
to the experimental value.
I will present an overview of the experiment, the technique used to
perform the measurement and how it succeded to reduce the total
uncertainty to a value close to 100ppb. The near term perspectives in
this field of research will also be described.

Speaker: On Kim (University of Mississippi)

Presentation_ID682_Kim.pptx

Parallel Session: 4_Hadron Structure and Reactions

Convener: Sangyong Jeon (McGill University)

188 Pion photoproduction of nucleon excited states with Hamiltonian effective field theory

We refine our previous calculation of multipole amplitude $E_{0+}$ for pion photoproduction process, γN→πN. The treatment of final-state interactions is based upon an earlier analysis of pion-nucleon scattering within Hamiltonian effective field theory, supplemented by incorporating contributions from the N(1650) and the KΛ coupled channel. The contribution from the bare state corresponding to the N(1650) significantly enhances our results. Additionally, we also compute the multipole amplitude $M_{1-}$, which is of direct relevance to the Roper resonance. The results are comparable with other dynamical coupled-channel models, even though the contribution from the bare state (interpreted as a 2s excitation) in this channel is small because of its large mass.

Speaker: Zhan-Wei Liu (Lanzhou University, China)

LIUZhanWei2025Korea.pdf

189 High-Precision Proton Charge Radius Experiments at Jefferson Lab

The proton charge radius $r_{p}$ is a fundamental quantity that characterizes the spatial distribution of the proton’s charge and serves as a crucial input for bound-state Quantum Electrodynamics calculations of hydrogen atomic energy levels. In 2010, a groundbreaking measurement using muonic hydrogen spectroscopy yielded an unprecedentedly precise result. However, this result sparked the “proton charge radius puzzle,” as it was 7$\sigma$ smaller than values obtained from previous electron-proton elastic scattering and ordinary hydrogen spectroscopy experiments. Despite significant experimental and theoretical advancements since then, key questions remain, particularly in lepton scattering. Notably, the proton electric form factor measured by the Jefferson Lab PRad experiment exhibits a large discrepancy from the 2010 Mainz results. In this talk, I will review recent progress in lepton scattering experiments, with an emphasis on the PRad measurement. I will also introduce the next-generation PRad-II experiment, which aims to reduce the total uncertainty of $r_{p}$ by at least a factor of 3 compared to PRad. This new experiment will push the precision frontier of electromagnetic interactions and address discrepancies in proton form factor and radius measurements across different scattering experiments.

Speaker: Weizhi Xiong (Shandong University)

PRad_INPC_2025_v1.pdf

190 H-dibaryon Search near the $\Lambda\Lambda$ and $\Xi^-p$ Thresholds in the ${}^{12}\mathrm{C}(K^-,K^+)$ Reaction

We present preliminary results from our search for the H-dibaryon near the $\Lambda\Lambda$ and $\Xi^-p$ mass thresholds using the E42 detector. The E42 experiment was designed to maximize sensitivity to both a loosely bound H-dibaryon and possible resonances near the $\Lambda\Lambda$ and $\Xi^-p$ thresholds by employing a dedicated Hyperon Spectrometer, whose main detector is a time-projection chamber (HypTPC) reconstructing all charged-particle trajectories originating from ${}^{12}\mathrm{C}(K^-,K^+)X$ reactions, enabling us to collect data with statistics two orders of magnitude higher than ever before.

In this talk, we will introduce the E42 apparatus and discuss our ongoing analysis, which aims to provide a definitive answer regarding the existence of the H-dibaryon based on the unprecedented statistical precision of the E42 dataset.

Speaker: Wooseung Jung (Korea University)

Presentation_ID506_JUNG.pdf

191 Nucleon-charmonium interactions from lattice QCD

We present a realistic lattice QCD study on low-energy $N$-$J/\psi$ and $N$-$\eta_c$ interactions based on (2+1) flavor configurations with nearly physical pion mass $m_\pi=146$ MeV.The interactions, extracted from the spacetime correlations of nucleon and charmonium system by using the HAL QCD method,are found to be attractive in all distances and possess a characteristic long-range tail consistent with the two-pion exchange potential. The resulting $S$-wave scattering lengths are $0.30(2)\left(^{+0}_{-2}\right)$ fm, $0.38(4)\left(^{+0}_{-3}\right)$ fm, and $0.21(2)\left(^{+0}_{-1}\right)$ fm for spin-$3/2$ $N$-$J/\psi$, spin-$1/2$ $N$-$J/\psi$, and spin-$1/2$ $N$-$\eta_c$, respectively. Our results are orders of magnitude larger than those from the photoproduction experiments assuming the vector meson dominance. Our findings may provide deeper understanding of the nonperturbative QCD phenomena ranging from the origin of nucleon mass to the in-medium $J/\psi$ mass modification as well as the properties of hidden-charm pentaquark states.

Speaker: Yan LYU (RIKEN)

Presentation_ID278_Lyu.pdf

192 Dbar-N interaction from Lattice QCD at physical point

The Dbar-N two-body system is one of the simplest and most important systems involving the charmed meson and nucleons. Because of the absence of quark-antiquark annihilation, the Dbar-N channel is entirely exotic so that a bound state would be a pentaquark state. In addition, an understanding of the Dbar-N interaction is sorely needed for studies of charmed nuclei and in-medium D-meson properties. However, the Dbar-N interaction has yet to be known in detail. While some EFT models predict a strong attraction forming a bound state, other models predict a weak attraction or repulsion [1]. Given this circumstance, realistic lattice QCD simulations could play an important role in guiding future theoretical studies involving the Dbar-N interaction.
In this talk, I will present preliminary results of the Dbar-N interaction and its scattering properties obtained from (2+1)-flavor lattice QCD simulations at physical point, which utilize gauge configurations generated by the HAL Collaboration on a $96^3\times96$ lattice with pion mass $m_\pi\simeq137$ MeV and lattice spacing $a\simeq0.0844$ fm [2].

References:
[1] J.Haidenbauer, G.Krein, U.-G.Meissner, A.Sibirtsev Eur. Phys. J. A33 (2007) 107–117; C.E. Fontoura, G. Krein, V.E. Vizcarra, Phys. Rev. C 87 (2) (2013) 025206; Y. Yamaguchi, S. Yasui, A. Hosaka, Phys. Rev. D 106, 094001 (2022)
[2] T. Aoyama et. al., (HAL QCD collaboration) arXiv:2406.16665

Keywords: Hadron-Hadron Interactions, Exotic Hadrons, Pentaquark, Charmed Nuclei, Lattice QCD

Speaker: Wren Yamada (RIKEN)

Presentation_ID219_Yamada.pdf

Parallel Session: 4_New Facilities and Instrumentation

Convener: Taeksu Shin (IRIS, IBS)

193 Streaming-readout data acquisition and processing system developed by SPADI Alliance

Needs for the high-throughput, trigger-less, and event-lossless data acquisition and processing system is becoming increasingly and commonly not only in high-energy but also in the low-energy nuclear-physics experiments in various accelerator facilities since the beam intensity (or luminosity) becomes higher and the granularity of the detectors becomes larger. This is a serious and common issue among many experimental groups in Japan. SPADI Alliance is initiated based on such demands to develop a common new-generation data acquisition and processing system. A new streaming-readout data acquisition and processing system with scalability has been developed by the SPADI Alliance. The new system has been employed in physics experiments performed using Grand Raiden magnetic spectrometer at RCNP (Osaka) and in detector development at J-PARC (Ibaraki). The new system can handled the total event rate of 200 kcps at RCNP, which is 20 - 40 times larger than the traditional system. The data throughput of 10 Gbps has been achieved at J-PARC. The whole system including the frontend electronics (TDC), the readout and processing software, and the analysis software is now being packaged for publication. In this paper, the overview of the new system is introduced and its performance is discussed.

Speaker: Shinsuke OTA (Research Center for Nuclear Physics)

Presentation_ID557_Ota.pdf

Presentation_ID557_Ota.pptx

194 Performance evaluation of the prototype beam drift chamber for LAMPS at RAON

The Beam Drift Chamber (BDC) is an essential detector for reconstruction of the beam trajectories entering the experimental target of LAMPS (Large Acceptance Multi-Purpose Spectrometer) at RAON (Rare isotope Accelerator complex for ON-line experiments), the rare isotope beam accelerator complex located in Daejeon, Korea. To assess the performance of the BDC, including track reconstruction efficiency and position resolution, a prototype BDC (pBDC) was manufactured and tested using ion beams at HIMAC (Heavy Ion Medical Accelerator in Chiba) facility in Japan. The evaluation employed two kinds of ion beams: 100 MeV proton, and 200 MeV/u $^{12}$C ions. This presentation will outline the construction details of the pBDC, followed by a detailed discussion of its performance.

Speaker: Dr Hyunchul Kim (Chonnam National University)

Presentation_ID451_Kim.pdf

195 Development of a HPGe Detector for Ultra High Rate Spectroscopy and Imaging

A prototype High Purity Germanium (HPGe) detector has been designed to maintain energy resolution and throughput performance at count rates in excess of 2 Mcps while providing fine 3D position sensitivity. Conventional HPGe detectors show significant degradation in performance at such count rates, limiting their use in applications including imaging for nuclear medicine, nuclear decommissioning and remediation, and the assay of spent nuclear fuel. The detector design, a double-sided strip detector with a strip pitch of 0.5 mm, was selected by performing analytical and numerical calculations of the expected efficiency, throughput, timing, energy resolution, and position resolution for various geometries and electrode configurations. Details of the design and predicted performance will be shown. Results from the fabrication and characterization of the prototype will be presented.

Speaker: Joanna Szornel (Lawrence Berkeley National Laboratory)

Presentation_ID184_Szornel.pptx

196 PARIS array – idea, status, first results and outlook

PARIS (Photon Array for studies with Radioactive Ion and Stable beams) is an international project aiming on developing and building a novel 4π γ-ray calorimeter, benefiting from recent advances in scintillator technology. It is intended to play the role of an energy-spin spectrometer, a calorimeter for high-energy photons and a medium-resolution gamma-detector. The PARIS is composed of two shells: the scintillators of the most advanced technology (LaBr3 or CeBr3) for the inner volume offering simultaneously high efficiency, excellent time resolution and relatively good energy resolution in a large energy range, and a more conventional scintillator (NaI) for the outer shell. The calorimeter is of high granularity and the basic element is made following the “phoswich” (PHOSphor sandWICH) concept – LaBr3 or CeBr3 scintillator in the front, optically connected to the NaI scintillator at the back, while the signals from both scintillators are read by fast photomultiplier connected to the NaI. The array can be used in a stand-alone mode, in conjunction with other detection systems, like germanium arrays (e.g., AGATA, EXOGAM), particle detectors (e.g., MUGAST, NEDA, FAZIA, ACTAR) or heavy-ion spectrometers (e.g., VAMOS, PRISMA). It will be used in experiments with both intense stable and radioactive ion beams to study the structure of atomic nuclei and new nuclear excitation modes as a function of angular momentum, isospin, and temperature, as well as reaction dynamics. The construction of the array is phased: from a single phoswich detector, via one cluster, or a limited number of clusters via mini-cube, and finally the ultimate 4π phase.

In the presentation the concept of the PARIS array will be described, status of its construction presented, results from the first experiments in different laboratories (GANIL Caen, IJC Lab Orsay, IFJ PAN Krakow) will briefly shown, as well as the near future perspectives for the use of PARIS will be listed.

Speaker: Prof. Adam Maj (IFJ PAN Krakow)

PARIS_ID481_Maj.pptx

197 Towards next-generation in-beam gamma-ray spectroscopy at the RIBF with HYPATIA

Since advent of the RIBF, the NaI(Tl) based scintillation array DALI2+ has been the workhorse for in-beam gamma-ray spectroscopy experiments. Due to its modest energy resolution, caused by large opening angles and intrinsic energy resolution of NaI(Tl) scintillators, long absorption lengths of the scintillation material, as well as modest time resolution, the long-term potential is limited. Furthermore, limited available budget makes low cost alternatives to 4pi Ge tracking arrays with superior features, except energy resolution, desirable. Consequently, a new-generation scintillator array for in-beam gamma-ray experiments, HYPATIA (HYbrid Photon detector Array To Investigate Atomic nuclei), is being devised for the near future. For the HYPATIA project, which launched in 2023, the scintillation materials GAGG and CeBr3 have been identified as the most promising scintillation detector choices. Key advantages for the former include its high density, low radiation length, and that it's neither hygroscopic nor self-emissive, while the latter offers a better intrinsic resolution and extremely fast decay time.

HYPATIA will be employed at different experimental stations of the next-generation RIBF and its magnetic spectrometers (ZeroDegree, SAMURAI, SHARAQ), each having different performance requirements and constraints. Key experiments to be carried out in the future at the RIBF at intermediate energies involve inelastic scattering on high-Z targets to induce Coulomb excitation, as well as inelastic scattering and quasi-free scattering on liquid hydrogen.

In my presentation, I will provide an overview of the planned array, the status of its development, and give examples of possible future experiments beyond spectroscopy of the first excited 2+ state.

Speaker: Pieter Doornenbal

198 TOGAXSI telescope: dawn of generalized nuclear clustering

The development of subsystems in matter is a phenomenon that appears in a wide field of physics.
Subsystems in nuclei are called "clusters", and they have been established for light nuclei and in $\alpha$-decay nuclei. However, very little is known about the situation in medium and heavy nuclei [1]. The ONOKORO project aims to conduct a systematic study of the cluster formation over a wide mass range by using the cluster knockout reaction at intermediate energy, utilizing the facilities in Japan: RCNP, HIMAC, and RIBF.

The construction of the TOGAXSI telescope is one of the important missions of this project to realize the measurements in inverse kinematics and is ongoing at RIBF.
Efforts to strengthen international collaborations have resulted in offers from IBS (Korea) and Peking University (China) to produce an additional 10 GAGG(Ce) crystals each.
This will significantly improve the efficiency, especially for deuterons and tritons, and thus maximize the outcome.

Meanwhile, the first comprehensive cluster knockout measurements for the stable nuclei $^{40,42,44,48}$Ca have been performed at the RCNP. Separation energy spectra for the deuteron, triton, $^3$He and $\alpha$ clusters have been obtained successfully. Complementary measurements using the TOGAXSI telescope for unstable nuclei $^{50\mbox{-}52}$Ca are planned for 2025 at RIBF.

Preliminary results will be presented and discussed together with the construction status of the TOGAXSI telescope and the preparation status for the upcoming measurements.

[1] T. Uesaka and N. Itagaki, Phil. Trans. R. Soc. A 382, 20230123 (2024).

Speaker: Tomohiro Uesaka (RIKEN)

Presentation_ID123_Kubota.pptx

Parallel Session: 4_Nuclear Astrophysics

Convener: Hye Young Lee (Los Alamos National Laboratory)

199 Galactic archaeology through chemo-dynamics of stars

The structure, formation and evolution of the Milky Way and the nearby universe are cutting-edge fields in contemporary astrophysics. The new era of large-scale surveys has provided us unexpected opportunities to deeply explore our home galaxy. This talk will focus on introducing the new picture of the Milky Way presented based on the modern astronomical observations specially through the Chinese LAMOST survey. From the origin of elements in the universe to the formation history of our Milky Way and its interaction with nearby neighbor galaxies, I shall present some of our latest understandings as well as breakthrough achievements obtained in the field of stellar and Galactic science.

Speaker: Haining Li (National Astronomical Observatories, Chinese Academy of Sciences)

Presentation_ID707_Li.pptx

200 The Galactic Aluminum Conundrum in the Light of New Data at Astrophysical Energies

The abundance of $^{26}$Al carries a special role in astrophysics, since it probes active nucleosynthesis in the Milky Way and constrains the Galactic core-collapse supernovae rate. It is estimated through the detection of the 1809 keV $\gamma$-line and from the superabundance of $^{26}$Mg in comparison with $^{24,25}$Mg in solar-system meteorites. For this reason, high precision is necessary also in the investigation of the stable Al and Mg isotopes.
These nuclei also enter the so-called MgAl cycle playing an important role in the production of $^{27}$Al and $^{24}$Mg. Recently, high-resolution stellar surveys have shown that the Mg-Al anti-correlation in red-giant stars in globular clusters may hide the existence of multiple stellar populations, triggering the acquisition of new high-precision astronomical data and the development of new stellar models.
The common thread running through these astrophysical scenarios is the $^{27}$Al(p,$\alpha$)$^{24}$Mg and $^{27}$Al(p,$\gamma$)$^{28}$Si reactions, which are the main $^{27}$Al destruction channels.
Since available spectroscopic data and reaction rates show large uncertainties owing to the vanishingly small cross section at astrophysical energies, we have applied the Trojan Horse Method to the reaction investigation.
This has allowed us to extract important information on the $^{27}$Al(p,$\alpha$)$^{24}$Mg and $^{27}$Al(p,$\gamma$)$^{28}$Si cross sections in the energy region of interest for astrophysics, below about 100 keV, not accessible to direct measurements.
In particular, the indirect measurement made it possible to assess the contribution of the 84~keV resonance and to lower upper limits on the strength of nearby resonances. Therefore, for both destruction channels a factor of 3 lower reaction rates have been determined with respect to those routinely used in present-day astrophysical models. Given the competition between the two destruction channels, important impact for astrophysics, especially for massive-star nucleosynthesis, is foreseen.

Speaker: Marco La Cognata (Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud)

Presentation_ID096_LaCognata.pdf

Presentation Slides (PDF/PPT ONLY) Presentation_ID096_LaCognata.pdf Presentation_ID096_LaCognata.pdf

201 Constraining a key s-process branching point through the $^{85g}$Kr(d,p$\gamma$) reaction

About 50% of the elements heavier than iron are produced in the so-called s-process, where the lifetime for neutron capture of the nuclei involved is typically longer than their $\beta$-decay lifetimes. In the modeling of the s-process, great uncertainty derives from the competition between neutron capture and $\beta$-decay, in particular in some isotopes called “branching points”. $^{85}$Kr is an important branching point of the s-process, that influences both the $^{86}$Kr/$^{82}$Kr ratio in presolar grains and the abundances of heavy Sr isotopes that are produced also by r-process. A better understanding of this branching point can be achieved only if the neutron capture cross section on $^{85}$Kr is sufficiently well constrained, but a direct measurement of this cross section is extremely challenging due to the radioactivity of the sample (T$_{1/2}$ = 10.7 yr). However, $^{85}$Kr can be accelerated as a pure beam, and the (d,p$\gamma$) reaction has been demonstrated to be a reliable indirect probe of the (n,$\gamma$)-reaction cross section.

The $^{85}$Kr(d,p$\gamma$)$^{86}$Kr reaction has been carried out at 10 MeV/u in inverse kinematics at Argonne's ATLAS facility using the HELIOS spectrometer and the Apollo array. Neutron excitations from around 2-14 MeV in $^{86}$Kr were populated, where S$_n$=9.86 MeV, with a Q-value resolution of about 150 keV. The coupling between Apollo and HELIOS allows to observe the $\gamma$-rays in coincidence with the protons, to determine the $\gamma$-ray emission probabilities as a function of excitation energy [P$_{p\gamma}$(E$_{ex}$)]. The $2^+ \to 0^+$ and $4^+ \to 2^+$ $\gamma$-rays are clearly observed, showing the characteristic constant value of P$_{p\gamma}$ below S$_n$ and a decrease above S$_n$. These data are used to extract the cross sections for $^{85}$Kr(n,$\gamma$) reaction, complementing recent direct, high-precision measurements on the stable Kr isotopes. This technique demonstrates significant potential for future indirect studies of the (n,$\gamma$) reaction.

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC02- 06CH11357 and by the National Science Foundation, USA under Grant No. PHY-2012522 (Florida State University’s John D. Fox Laboratory). This research used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility.

Speaker: Sara Carollo (University of Padova and INFN Padova)

Presentation_ID172_Carollo.pdf

Presentation_ID172_Carollo.pdf

202 The ILIMA@ESR Program at GSI/FAIR - Present and Future

The ILIMA (Isomers, LIfetimes, and MAsses) collaboration aims at precision measurements of atomic masses and lifetimes of exotic nuclei and isomers, as well as the exploration of rare decay phenomena of highly-charged (radioactive) ions. Originally it was planned to carry out this unique research program at dedicated new storage rings to be built with the FAIR project. However, since these constructions have been postponed to a later stage, the collaboration is now continuing to employ and extend their program with new and upgraded detector setups at the existing Experimental Storage Ring (ESR).

I will give an overview about recent experiments measuring rare decay modes that can only appear in highly-charged ions. The measurement of the bound-state beta-decay of 205Tl(81+) has been proposed 30 years ago. However, only recently it could be measured at the ESR and its astrophysical impact on the production of the short-lived radioactive s-only isotope 205Pb [G. Leckenby et al., Nature 635, 321 (2024)] and the potential measurement of the long-term solar neutrino flux in the LOREX project [R.S. Sidhu, PRL 133, 232701 (2024)] be determined.
Another highlight has been the measurement of the isolated two-photon decay in 72Ge [D. Freire-Fernandez et al., PRL 133, 022502 (2024)] where the first excited state is a 0+ state at 691 keV. This second-order electromagnetic process normally competes with internal conversion in neutral atoms and electron-positron pair creation if the excited state is above the 1022 keV production threshold. In fully ionized 72Ge(32+) the partial half-life of the 0+ state was measured to be ~24 ms and thus deviates strongly from expectations.
These recent successes have motivated many new measurements and proposals, highlighting the bright future of the ILIMA@ESR collaboration in the next years.

Speaker: Iris Dillmann (TRIUMF)

Presentation_ID270-Dillmann-updated.pdf

203 The $^3$He(n,p)$^3$H reaction cross section measured at Big Bang energies

Neutron induced nuclear reactions play an important role in the Big Bang Nucleosynthesis. Their excitation functions are, from an experimental point of view, usually difficult to measure. Nevertheless, in the last decades big efforts have led to a better understanding of their role in the primordial nucleosynthesis network. In this work, we apply the Trojan Horse Method to extract the cross section at astrophysical energies for the $^3$He(n,p)$^3$H reaction after a detailed study of the $^2$H($^3$He,pt)H three-body process. Data extracted from the present measurement are compared with other published sets. The reaction rate is also calculated and the impact on the Big Bang Nucleosynthesis is examined in detail.

Speaker: Rosario Gianluca Pizzone (University of Catania and Istituto Nazionale di Fisica Nucleare)

ID_226_pizzone.pptx

Parallel Session: 4_Nuclear Reactions (1)

Convener: Toshimi Suda (Tohoku University)

204 Level density parameters and fission probabilities along fission paths

We employ a statistical approach to investigate the influence of axial asymmetry on the nuclear level density and entropy along the fission pathways of a superheavy nucleus, specifically focusing on the $^{296}$Lv isotope. These pathways are determined within multidimensional deformation spaces. Our analysis reveals a significant impact of triaxiality on entropy. Additionally, suppressing shell effects can alter the fission scenario depending on the available excitation energy. We derive the deformation-dependent level density parameter, which plays a crucial role in estimating the survival probability of a superheavy nucleus. Furthermore, we utilize a master equation to solve for the time-dependent fission probabilities and calculate the ratio of decay probabilities for both axial and triaxial paths.

Speaker: Nikolai Antonenko (BLTP, JINR)

PresentationID74_Antonenko.pdf

205 New perspectives for cold and hot fusion reactions

Optimal reactions to produce superheavy nuclei are discussed. The models of fusion are reviewed. The dependence of calculated evaporation residue cross sections on the predicted nuclear properties is presented. The reactions are suggested to produce nuclei with Z=119 and 120, and unknown isotopes of superheavy nuclei. The evaporation residue cross sections are predicted for future experiments. The relationship between the self-consistent methods and microscopic–macroscopic approaches is considered.

Speaker: Gurgen Adamian (BLTP, JINR)

AdamianG-25.pdf

206 Producing Dubnium with a 50Ti beam: A first step towards discovering new elements with the Berkeley Gas-filled Separator and refining the Db and Rf decay properties

For many years, element discoveries have become synonymous with a 48Ca beam on an actinide target. However, as we move towards discoveries of elements heavier than 118 we have to find new beam-target combinations and use beams of heavier proton numbers. At Berkeley Lab we investigate the use of 50Ti as such an alternative.
As a first step in this development, we produced 50Ti11+ with the VENUS source and used it to make 257Db using the 50Ti+209Bi fusion evaporation reaction in the Berkeley Gas-filled Separator (BGS). During the experiment, we were able to identify 257Db events through EVR-a-a coincidences and EVR-fission coincidences using our newly commissioned detector: the SuperHeavy RECoil detector (SHREC). As a second part in this experiment, we ramped our beam energy by 24 MeV and looked into the 3n, 4n and pxn channels of the 50Ti+209Bi reaction. The results of this experiments and their impact on what we know about the relevant Dubnium and Rutherfordium isotopes will be presented.

Speaker: Dr Marilena Lykiardopoulou (Lawrence Berkeley National Lab)

Presentation_ID182_Lykiardopoulou.pptx

207 Study of the influence of the projectile nucleus structure on the interacting mechanism in cold fusion reactions

Cold fusion reactions are one of the successful ways for superheavy element synthesis. The largest evaporation residue (ER) formation cross-section was found in the reaction 48Ca+208Pb. For the reactions with other Ca isotopes, as well as 40Ar and 50Ti ER cross sections are one or even two orders of magnitude lower compared to 48Ca projectile.
The 48Ca nucleus has a unique structure. It is doubly magic nucleus (Z=20, N=28), consisting of 40Ca core and a neutron skin. In order to investigate the impact of structural peculiarities of the projectiles near 48Ca in the cold fusion reactions on the capture process and the further evolution of the formed dinuclear system, the capture cross sections and mass-energy distributions of binary fragments formed in the reactions 40Ar, 40Ca, 44Ca, 48Ca, 50Ti + 208Pb at interaction energies above and well below the Coulomb barrier have been measured. The separation of fusion-fission component from the quasifission one is based on the analysis of the properties of measured mass-energy distributions for fission-like fragments. The influence of two additional or deficient protons or neutrons in the projectile on the reaction dynamics will be discussed.
All experiments were carried out at the U-400 accelerator FLNR JINR, Dubna. The CORSET double-arm time-of-flight spectrometer was used to measure mass and energy distributions of the reaction products.

Speaker: Dr Kirill Novikov (Joint Institute for Nuclear Research)

Presentation_ID164_Novikov.pptx

208 Probing fusion inhibition in $^{\mathbf{19}}$F+$^{\mathbf{197}}$Au via measurement of spin distribution

Probing fusion inhibition in $^{19}$F+$^{197}$Au via measurement of spin distribution

Gonika$^1$, J. Gehlot$^1$, V. I. Chepigin$^2$, M. L. Chelnokov$^2$, T. Varughese$^1$, Tathagata Banerjee$^{1,a}$, A. Jhingan$^1$, S. Nath$^{1,b}$, I. Mazumdar$^3$, N. Madhavan$^1$ and A. V. Yeremin$^{2,c}$

$^1$Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India
$^2$Flerov Laboratory of Nuclear Reactions, JINR, Dubna 141980, Russia
$^3$Tata Institute of Fundamental Research, Mumbai 400005, India

$^a$Present address: Universita degli Studi di Napoli "Federico II", 80126 Napoli, Italy
$^b$Email: subir@iuac.res.in
$^c$Deceased

Search for optimum conditions for synthesis of superheavy elements [1] has been a major impetus for the study of fusion between two heavy nuclei over the last several decades. Formation of a compound nucleus (CN), equilibrated in all degrees of freedom, following capture of the colliding system in a potential well is severely hindered because of the presence of fission-like processes. Further, survival of the CN, in the form of a heavy evaporation residue (ER), has an extremely low probability because fission becomes the dominant decay mode for very heavy CN. To understand the complex dynamics of fusion between two heavy nuclei, a host of experimental probes are employed. It becomes quite difficult to experimentally segregate the events leading to formation of the CN from the overwhelmingly dominant events arising out of non-compound fission-like processes, as the experimental observables in the two cases often have overlapping characteristics. Observation of ERs serves as the most definitive signature of formation of the CN.

Berriman $\textit{et al.}$ [2] conducted measurements of ER cross sections and fission fragment (FF) mass distributions for three reactions, $\textit{viz.}$, $^{12}$C+$^{204}$Pb, $^{19}$F+$^{197}$Au and $^{30}$Si+$^{186}$W, all leading to the same CN $^{216}$Ra$^*$. Signature of quasifission was found in the reactions involving heavier projectiles [2,3]. However, several other studies of the reactions $^{19}$F+$^{197}$Au didn't find evidence of quasifission in this reaction and the experimental observables, $\textit{viz.}$, FF angular [4] and mass [5] distributions and $\alpha$-particle multiplicities [6] in coincidence with FFs, could be explained by the statistical model. The discrepancy between these studies call for further investigations.

Here we report an attempt to resolve the inconsistency in the decay dynamics of less-fissile systems like $^{19}$F+$^{197}$Au by measuring ER-gated spin ($\ell$) distributions. Results from such studies, especially the angular momenta that survive fission and fission-like processes to yield cold ERs in the ground state, might be useful in developing more reliable theoretical models to describe fusion between two massive nuclei.

The experiment was conducted using the HYbrid Recoil mass Analyzer (HYRA) [7] in gas-filled mode, coupled with the TIFR 4$\pi$ spin spectrometer [8], at IUAC, New Delhi. A pulsed $^{19}$F beam from the 15UD Pelletron, with a pulse separation of 2 $\mathrm{\mu}$s, was bombarded onto a 250 $\mathrm{\mu}$g/cm$^2$ thick $^{197}$Au target. Beam energy ($E_{\mathrm{lab}}$) ranged from 86 to 112 MeV. ERs were separated from the more dominant background events by the HYRA and subsequently detected at its focal plane using a multi-wire proportional counter. To determine $\ell$-distribution, the TIFR 4$\pi$ spin spectrometer [8], comprising 32 NaI(Tl) scintillation detectors, arranged in a soccer-ball geometry around the HYRA target chamber, was employed. The spectrometer recorded the fold distributions of low-energy non-statistical $\gamma$-rays, emitted during decay of the ERs.

Raw $\gamma$-fold distribution was gated with the ERs detected at the focal plane, at each $E_{\mathrm{lab}}$, to obtain the true ER $\gamma$-fold distributions. The conversion of measured fold distribution to $\ell$-distribution was carried out in two steps. First, the fold distribution was converted into the $\gamma$-multiplicity distribution and then the multiplicity distribution was transformed to the angular momentum distribution. The $\gamma$-multiplicity distribution was constructed using a detector response matrix, which was computed through a recursive algorithm [9]. The multiplicity distribution was assumed to have the form of a Fermi function with two adjustable parameters, $\textit{viz.}$, the mean $\gamma$-multiplicity ($M_0$) and the diffuseness ($\Delta M$) in the multiplicity distribution. These two free parameters were varied to achieve the best fit of the experimental $\gamma$-fold distribution.

The $\ell$-distribution was obtained from the $\gamma$-multiplicity distribution, by the application of a generalized relation [10] between mean $\gamma$-multiplicity $\langle M_\gamma \rangle$ and mean angular momentum $\langle \ell_{\mathrm{CN}} \rangle$, according to the decay pattern of the CN. Based on the level scheme of dominant ERs, average spin carried away by each non-statistical $\gamma$-ray was estimated to be $\sim 1.7 \hbar$. Further, moments of the multiplicity distribution were extracted. It was observed that the third moment, $\textit{i.e.}$, skewness decreased gradually with increase in $E_{\textrm{lab}}$. This might be interpreted as reduced survival probability of higher $\ell$ at higher excitation energies. It is a challenge to determine experimentally whether non-survival of higher angular momenta is due to the entrance channel dynamics or has its origin in the statistical decay of the excited CN.

Dynamical model calculations, to describe evolution of the di-nuclear system, starting from the touching configuration, will complement these experimental results. Efforts to obtain a comprehensive theoretical understanding of the intricate reaction dynamics is ongoing.

[1] Odile R. Smits $\textit{et al.}$, Nat. Rev. Phys. $\textbf{6}$, 86 (2024).
[2] A. C. Berriman $\textit{et al.}$, Nature (London) $\textbf{413}$, 144 (2001).
[3] D. J. Hinde $\textit{et al.}$, J. Nucl. Radiochem. Sci. $\textbf{3}$, 31 (2002).
[4] R. Tripathi $\textit{et al.}$, Phys. Rev. C $\textbf{71}$, 044616 (2005).
[5] R. Tripathi and A. Goswami, Eur. Phys. J. A $\textbf{26}$, 271 (2005).
[6] H. Ikezoe $\textit{et al.}$, Phys. Rev. C $\textbf{42}$, 342 (1990).
[7] N. Madhavan $\textit{et al.}$, Pramana - J. Phys. $\textbf{75}$, 317 (2010).
[8] G. Anil kumar $\textit{et al.}$, Nucl. Instrum. Methods A $\textbf{76}$, 611 (2009).
[9] A. Maj $\textit{et al.}$, Nucl. Phys. A $\textbf{571}$, 185 (1994).
[10] A. M. Stefanini $\textit{et al.}$, Nucl. Phys. A $\textbf{548}$, 453 (1992).

Speaker: Subir Nath (Inter-University Accelerator Centre)

Presentation_ID407_Nath.pdf

Parallel Session: 4_Nuclear Reactions (2)

Convener: Masaaki Kimura (RIKEN Nishina Center)

209 Investigation of non-fusion reaction products in the $^{51}$V + $^{248}$Cm → $^{299}$119* fusion-evaporation reaction

The extremely low production cross-sections involved in the search for new elements and isotopes at the edges of the nuclear chart require highly optimized experimental setups and conditions. A thorough understanding of the data collected is essential to exclude potential contamination from other reaction products in the detection system.
The ongoing search for element Z = 119 is conducted at the RIKEN Nishina Center using the $^{51}$V + $^{248}$Cm → $^{299}$119* fusion-evaporation reaction at the SRILAC/GARIS-III facility [1,2]. During this search, many parasitic reaction products are also transported into the decay station of the GARIS-III setup. These products generate decay signals characterized by a wide range of decay times and energies, some of which overlap with the expected region of interest for the Z = 119 decay chain.
These reaction products predominantly arise from quasi-fission and fusion-fission processes during the fusion-evaporation reaction. They exhibit an isotropic distribution northeast of $^{208}$Pb, with an average mass A = 219−220, and their decay times span from nanoseconds to days. Those events were identified using both electronic systems currently implemented in the GARIS-III setup: the Mesytec-based Analog DAQ and the Pixie-16 digital electronics [3]. This study presents the methodologies and efficiencies of these data acquisition systems in identifying fast-decay events.
The measured isotropic distribution has similar characteristics to previous studies of hot fusion reaction with actinide targets [4]. However, thanks to the addition of the fast and efficient digital electronics and the higher total dose, this distribution is also slightly wider. Direct identification of isotopes at N = 128 as well as some protactinium isotopes were made possible. Additionally, the implantation profiles measured in this study show significantly different characteristics than the previous studies [4], both in terms of the energy spectrum and profile/transportation.
Consequently, the accurate identification of all these reaction products within the detection setup was crucial to ensure uncontaminated and precise search. In addition, the digital electronics analysis allows to reduce significantly the signal in the region of interest for the search of new element Z = 119. This reduction arises from the waveform analysis and the pile up detection that the Pixie-16 board offers [3].

References
[1] D. Kaji, et al. “Gas-filled recoil ion separator garis-II”. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 317:311-314, 2013.
[2] Sakai, H., Haba, H., Morimoto, K. Sakamoto, N., “Facility upgrade for superheavy-element research at RIKEN”. The European Physical Journal A. 58, 238 (2022).
[3] Brionnet, Pierre, et al. “Development of digital electronics for the search of SHE nuclei using GARIS-II/III at RIKEN.” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1049 (2023): 168068.
[4] A. Di Nitto et al., “Study of non-fusion products in the Ti50+Cf249 reaction”, Physics Letters B 784, 199 (2018).

Speaker: pierre brionnet (Super heavy team, NISHINA Center, RIKEN)

INPC_Brionnet_25.pptx

210 Production of neutron-rich nuclei in the vicinity of 78Ni: Fragmentation reactions of unstable 81Ga and 82Ge beams

Neutron-rich nuclei in the vicinity of doubly-magic nucleus $^{78}$Ni ($Z=28, N=50$) is important for both nuclear physics and astrophysics. To explore these very neutron-rich isotopes, the question of how to produce them effectively in a laboratory arises. So far, two methods are widely used for production of neutron-rich nuclei: fragmentation of relevant stable nuclei and induced fission of $^{238}$U. However, for the production of most neutron-rich nuclei in the $^{78}$Ni region, both projectile fragmentation and the fission of $^{238}$U encounter difficulties. For projectile fragmentation, no suitable relevant stable nuclei are available as projectiles. In the case of in-flight fission, the production cross sections dramatically decrease towards the very neutron-rich side.

Recently, a new method of the two-step scheme by combing ISOL and in-flight fragmentation has been proposed to produce very neutron-rich nuclei in “next-generation” facilities, such as EURISOL, BISOL and RAON. In order to evaluate the potential of the two-step scheme in producing exotic isotopes in the vicinity of $^{78}$Ni, the fragmentation reactions of unstable nuclei $^{81}$Ga ($Z=31, N=50$) and $^{82}$Ge ($Z=32, N=50$) at 250 MeV/nucleon have been measured at RIKEN RIBF. The $^{81}$Ga and $^{82}$Ge beams were produced by in-flight fission of $^{238}$U primary beam in BigRIPS separator. A 1.89-g/cm$^2$ $^{9}$Be target was used to induce the fragmentation reactions. The reaction products were analyzed by the ZeroDegree spectrometer. For the first time, the fragmentation cross sections for very neutron-rich nuclei around $^{78}$Ni were obtained. The newly measured cross sections were compared with various calculations. These data enable to make a comparison between the two-step and one-step methods for the production of extremely neutron-rich nuclei in the $N = 50$ region. In the presentation, the cross section results as well as the potential of two-step scheme in the production of very neutron-rich nuclei near $^{78}$Ni will be discussed.

Speaker: Xiaohui Sun (Huzhou University)

Presentation-ID125-SUN.pdf

211 Investigation of $^{51}$V+$^{159}$Tb reaction for estimating optimal reaction energy for new element synthesis

Recently, elements up to oganesson have been discovered, completing the seventh period of the periodic table. Search for new elements of the eighth period is being conducted at several facilities. At RIKEN, element 119 is being searched using a $^{51}$V+$^{248}$Cm hot fusion reaction. Since the production rate of the superheavy elements is extremely low and even a few percent change in the reaction energy can reduce it by more than one order of magnitude, the reaction energy is a crucial experimental parameter in the search of new elements. However, its theoretical predictions range widely, and it is difficult to estimate it theoretically at this moment. Under these circumstances, we have been developing a method to estimate the optimal reaction energy based on the experimentally obtained quasielastic barrier distribution [1,2].
Although this estimation method has been investigated while fixing the target particle as $^{248}$Cm and changing the beam from $^{22}$Ne to $^{48}$Ca, there has been no systematic study while fixing the beam as $^{51}$V and changing the target. It is important to investigate the relation between the optimal reaction energy and the barrier distribution by changing the target particles in a wide range to extend our knowledge to $^{248}$Cm, which is the heaviest target that we use.
In this study [3], we measured the fusion reaction and quasielastic scattering of the $^{51}$V+$^{159}$Tb system at SRILAC using GARIS-III [4]. The former and the latter data are used to determine the optimal reaction energy and the quasielastic barrier height respectively, which are compared to investigate the mechanism of the heavy-ion fusion reaction involving a deformed target nucleus. The results support the hypothesis that nuclear deformation is crucial in determining the optimal reaction energy in fusion reactions. In this presentation, we will report on the measurement methods, analysis, and results.

[1] T. Tanaka et al., Phys. Rev. Lett. 124, 052502 (2020).
[2] M. Tanaka, S. Sakaguchi et al., J. Phys. Soc. Jpn. 91, 084201 (2022).
[3] P. Brionnet et al., accepted for publication in Phys, Rev. C
[4] H. Sakai et al., Eur. Phys. J. A 58, 238 (2022).

Speaker: Yuki Yamanouchi (Kyushu University)

Presentation_ID157_Yamanouchi.pdf

212 Study of Total Cross Sections for the Reactions $^{10,11,12}$Be+$^{28}$Si

The study of the total cross sections for the reactions involving neutron-rich weakly bound nuclei at low and intermediate energies makes it possible to obtain information on their structure (halo, skin, effective matter radii) and its manifestation in nuclear reactions [1, 2].

In this work, we studied the total reaction cross sections for the $^{10,11,12}$Be nuclei on the $^{28}$Si target by the 4π method based on the registration of the prompt γ quanta and neutrons accompanying the interaction using the multidetector spectrometer. The procedure of processing of the obtained experimental data included taking into account the probability distribution of the number of triggered spectrometer detectors [3].

Using the measured values of the total reaction cross sections and the phenomenological optical model, the effective matter radii of the $^{10,11,12}$Be nuclei were determined. A new approach based on the combination of the optical model with the modified optical potential and classical trajectories was applied to the calculations of the effective matter radii of the colliding nuclei (details are given in [3]).

The total reaction cross sections for the $^{11}$Be nuclei are significantly larger than those for $^{10}$Be. Along with the low value of the neutron separation energy (0.5 MeV) for $^{11}$Be, it is an indication of its halo structure. The total reaction cross sections for the $^{12}$Be nuclei are larger than those for $^{10}$Be. Along with the pairing of two outer neutrons and the larger value of the neutron separation energy (3.2 MeV) for $^{12}$Be, it is an indication of its more compact outer shell (compared to a halo) which can be called a skin.

References

1. Yu. E. Penionzhkevich, Phys. At. Nucl. 74, 1615 (2011).
2. Yu. E. Penionzhkevich and R. G. Kalpakchieva, Light Exotic Nuclei Near the Boundary of Neutron Stability (World Scientific, Singapore, 2021).
3. Yu. G. Sobolev, V. V. Samarin, Yu. E. Penionzhkevich, S. S. Stukalov, and M. A. Naumenko, Phys. Rev. C 110, 014609 (2024).

Speaker: Mikhail Naumenko

Presentation_292_Naumenko.ppt

213 Nuclear Fragmentation at the Future Electron-Ion Collider

I will discuss low-energy nuclear physics at the future Electron-Ion Collider (EIC) at Brookhaven. By comparing the standard theory of electron-nucleus scattering with the equivalent photon method applied to Ultraperipheral Collisions (UPC) at the Large Hadron Collider (LHC) at CERN. In the limit of extremely high beam energies and small energy transfers, very transparent equations emerge. We apply these equations to analyze nuclear fragmentation in UPCs at the LHC and scattering at the EIC, demonstrating that the EIC could facilitate unique photonuclear physics studies. However, we have also shown that the fragmentation cross-sections at the EIC are about 1,000 times smaller than those at the LHC. At the LHC, the fragmentation of uranium nuclei displays characteristic double-hump mass distributions from fission events, while at the EIC, fragmentation is dominated by neutron emission and fewer few fission products, about 10,000 smaller number of events.

Speaker: Carlos Bertulani (East Texas A&M University)

Bertulani-INPC2025.pdf

214 Fragmentation reaction study on long-lived fission product 137Cs

Treatment on high-level radioactive waste from nuclear power plants is one of the major issues in worldwide for the use of a nuclear power plant. As a promising solution, research and development has been devoted to the partitioning and transmutation technology where long-lived nuclides are converted to stable or short-lived ones for reduction and recycling. In particular, the transmutation on the long-lived fission products (LLFPs) has received much attention because the LLFP nuclei have large radiotoxicities and they can be produced continuously in the accelerator driven systems and next-generation nuclear reactors. However, experimental reaction data for LLFP nuclei are very limited.
Nuclear physics plays an essential role in addressing the treatment on LLFP, because the reliable reaction data and models are necessary towards a possible solution for LLFP transmutation. Aiming at bringing an invention to the nuclear transmutation on LLFP, we have studied the fragmentation reaction of long-lived fission product $^{137}\rm{Cs}$ at 200 MeV/u at the RIKEN RI beam factory. In addition to transmutation, fragmentation reaction plays an important role in the production of radioactive beams. Experimental data of cross sections on the fragmentation of $^{137}\rm{Cs}$ reaction will lead to a better understanding on the reaction mechanism.
To study the fragmentation of $^{137}\rm{Cs}$ the inverse kinematics technique was adopted. Namely, the $^{137}\rm{Cs}$ beam was produced by a fission of U beam and selected using the in-flight separator BigRIPS. A carbon target was used to induce the fragmentation reaction, and the reaction products were identified and analyzed using the Zero Degree spectrometer. The reaction energy was around 200 MeV/u. The isotopic distribution of the reaction cross sections has been obtained and the results are compared with various theoretical calculations with dynamical and evaporation processes as well as semi-parameterization EPAX 3.1.a.
In the presentation, the newly obtained carbon-induced fragmentation cross sections of $^{137}\rm{Cs}$ will be discussed and a comparison with theoretical calculations will be presented.

Speaker: Enqiang Liu (Institute of Modern Physics, Chinese Academy of Sciences)

Presentation_ID64_LIU.pdf

Parallel Session: 4_Nuclear Structure (1)

Convener: Katarzyna Wrzosek-Lipska (Heavy Ion Laboratory, University of Warsaw)

215 Surrogate Reactions at Heavy-Ion Storage Rings

To understand the processes leading to the formation of heavy elements in stars, it is essential to have detailed knowledge of neutron-induced cross-sections [1]. In the context of rapid neutron capture (r-process), direct measurement of these cross-sections is often impractical due to the short lifetimes and high radioactivity of the relevant nuclei. A common method to address these challenges is the use of surrogate reactions. In this approach, the compound nucleus of interest is produced through an alternative, experimentally accessible reaction [2]. However, using this method in direct kinematics presents challenges, such as significant background noise, low efficiency and difficulties in detecting low-energy neutrons.

To address these issues, we proposed the NECTAR (NuclEar reaCTions At storage Rings) project [3], which aims to measure different decay probabilities using inverse kinematics in a heavy-ion storage ring. This approach offers the significant advantage of directly detecting heavy fragments produced after the de-excitation of the compound nucleus, fragments that would otherwise be stopped in a target, instead of neutrons or gamma rays. The NECTAR project enables simultaneous measurement of gamma emission, neutron emission, and fission probability with unprecedented precision and efficiency.

In 2022, we conducted an experiment at the ESR storage ring at GSI/FAIR, during which we measured, for the first time, the neutron emission probability in the $^{208}$Pb($p,p’$) reaction [3], as well as the gamma emission probability [4], achieving a detection efficiency close to 100%. Following this successful experiment, the experimental setup was upgraded with the fission detectors, preparing it for the next experiment in 2024. This time, we used a beam of $^{238}$U and a deuteron target, enabling the simultaneous investigation of two excited nuclei, $^{238}$U and $^{238}$U produced in the $^{238}$U($d,d’$) $^{238}$U($d,p$) reactions respectively. We measured not only the gamma and neutron emission probabilities but also the probabilities for the emission of two and three neutrons, as well as the fission probability. This comprehensive approach allowed for the measurement of all possible decay channels within this excitation energy range in a single experiment with unprecedented detection efficiency. This contribution will discuss the methodological and technical advancements achieved under the NECTAR project and present the results obtained from the most recent experiment utilizing a uranium beam.

[1] M. Arnould and S. Goriely, Prog. Part. Nucl. Phys. \textbf{112}, (2020) 103766.
[2] R. Perez Sanchez et al., Phys. Rev. Lett. \textbf{125}, (2020) 122502
[3] https://www.lp2ib.in2p3.fr/nucleaire/nex/erc-nectar/
[4] M. Sguazzin et al., accepted in Phys. Rev. Lett. https://arxiv.org/abs/2312.13742
[5] M. Sguazzin et al., accepted in Phys. Rev. C https://arxiv.org/abs/2407.14350

To understand the processes leading to the formation of heavy elements in stars, it is essential to have detailed knowledge of neutron-induced cross-sections [1]. In the context of rapid neutron capture (r-process), direct measurement of these cross-sections is often impractical due to the short lifetimes and high radioactivity of the relevant nuclei. A common method to address these challenges is the use of surrogate reactions. In this approach, the compound nucleus of interest is produced through an alternative, experimentally accessible reaction [2]. However, using this method in direct kinematics presents challenges, such as significant background noise, low efficiency and difficulties in detecting low-energy neutrons.

To address these issues, we proposed the NECTAR (NuclEar reaCTions At storage Rings) project [3], which aims to measure different decay probabilities using inverse kinematics in a heavy-ion storage ring. This approach offers the significant advantage of directly detecting heavy fragments produced after the de-excitation of the compound nucleus, fragments that would otherwise be stopped in a target, instead of neutrons or gamma rays. The NECTAR project enables simultaneous measurement of gamma emission, neutron emission, and fission probability with unprecedented precision and efficiency.

In 2022, we conducted an experiment at the ESR storage ring at GSI/FAIR, during which we measured, for the first time, the neutron emission probability in the
Pb() reaction [3], as well as the gamma emission probability [4], achieving a detection efficiency close to 100%. Following this successful experiment, the experimental setup was upgraded with the fission detectors, preparing it for the next experiment in 2024. This time, we used a beam of U and a deuteron target, enabling the simultaneous investigation of two excited nuclei, U and U produced in the U() U(

) reactions respectively. We measured not only the gamma and neutron emission probabilities but also the probabilities for the emission of two and three neutrons, as well as the fission probability. This comprehensive approach allowed for the measurement of all possible decay channels within this excitation energy range in a single experiment with unprecedented detection efficiency. This contribution will discuss the methodological and technical advancements achieved under the NECTAR project and present the results obtained from the most recent experiment utilizing a uranium beam.

[1] M. Arnould and S. Goriely, Prog. Part. Nucl. Phys. \textbf{112}, (2020) 103766.
[2] R. Perez Sanchez et al., Phys. Rev. Lett. \textbf{125}, (2020) 122502
[3] https://www.lp2ib.in2p3.fr/nucleaire/nex/erc-nectar/
[4] M. Sguazzin et al., accepted in Phys. Rev. Lett. https://arxiv.org/abs/2312.13742
[5] M. Sguazzin et al., accepted in Phys. Rev. C https://arxiv.org/abs/2407.14350

Speaker: Boguslaw Wloch (Université de Bordeaux, CNRS, LP2I Bordeaux, 33170 Gradignan, France)

632_WLOCH_v3.pdf

632_WLOCH_v4.pdf

216 Study of cosmic muon induced gamma background for rare decays

Abstract
Understanding and mitigation of background plays a crucial role in rare decay studies [1] and measurements of low cross sections relevant to nuclear astrophysics processes [2]. While anti-Compton shield (ACS) helps in enhancing the photopeak efficiency, muon induced interactions in the ACS can introduce additional background. With this motivation, measurements are carried out using low background counting setup CRADLE at TIFR (Mumbai) [3], comprising a 35$\%$ carbon fiber body HPGe detector surrounded by a 2.5 cm thick annular BGO shield and low activity lead shield (~ 10 cm). Two plastic scintillators (50 cm $\times$ 50 cm $\times$ 1 cm) are positioned on the top of the HPGe setup for detection of muons. Data was recorded using a CAEN N6724 digitizer (14-bit, 100 MS/s) with the BGO for 30 days and without the BGO for 15 days. Analysis is carried out for both these configurations, with and without plastic coincidence, in ROOT with appropriate time normalisation and chance corrections.
$\hspace{1cm}$ In singles spectra, several additional gamma rays are observed and intensity of a few other background lines like 1460 keV is enhanced. However, in the muon gated spectra, no additional n-induced gamma ray are observed at the measured level of the sensitivity. For $^{96}$Zr beta decay, that is $^{96}$Zr ${\rightarrow}$ $^{96}$Nb $\rightarrow$ $^{96}$Mo$^*$, the regions of interest (ROI) are near the expected photopeaks of 569, 778 and 1091 keV [4]. Hence, 569 keV arising from $^{207}$Pb(n,n$^\prime\gamma)$ can be a source of background. Measurements with CsI annular shield are also in progress. A comparison of background improvements with CsI and BGO annular shields will be presented together with Geant4 simulations.

References
[1] Dolinski et al., Annual Review of Nuclear and Particle Science, 69, 219, (2019)
[2] Denise Piatti, EPJ Web Conf. 297, 01009 (2024)
[3] G. Gupta et al., Proceedings of the DAE Symp. on Nucl. Phys. 63, 232, (2018)}
[4] S. Thakur, et al., Il Nuovo Cimento C 45, 24 (2022)

Speaker: Santhosh Telagasetti (Tata Institute of Fundamental Research)

Presentation_ID605_Telagasetti.pdf

217 Spectrum-shape method for studying the forbidden beta decay of $^{210}$Bi using PbMoO$_4$ cryogenic detectors

The spectrum-shape method has been proposed to determine the effective value of the axial-vector coupling constant (g$_A$) with the vector coupling constant (g$_v$=1) in forbidden nonunique beta decays. $^{210}$Bi is an isotope undergoing a first-forbidden nonunique beta decay, and its shape function exhibits strong sensitivity to g$_A$.
Given the short half-life of $^{210}$Bi, the decay chain $^{210}$Pb ($\beta$, T$_{1/2}$=22.3 y) $\rightarrow$ $^{210}$Bi ($\beta$, T$_{1/2}$=5.0 d) $\rightarrow$ $^{210}$Po ($\alpha$, T$_{1/2}$=138 d) was utilized. PbMoO$_4$ cryogenic detectors were employed for their high detection efficiency (source = detector configuration) and excellent energy resolution. Two detectors of identical geometric design and crystal size (1 cm$^3$) were prepared. One PbMoO$_4$ crystal was grown using modern lead, yielding a $^{210}$Pb radioactivity of about 30 Bq/kg. The second PbMoO$_4$ crystal was made with archaeological lead, characterized by significantly reduced $^{210}$Pb radioactivity (about 0.2 Bq/kg), enabling background rejection with minimal systematic error. Both detectors were installed adjacently in a cryogen-free dilution refrigerator.
This presentation will outline the detection system's design and performance and present preliminary beta decay spectrum analysis results.

Speaker: Hyelim Kim (Institute for basic science)

Presentation_ID553_Kim.pdf

218 Global Rare Anomalous Nuclear Decay Experiment (GRANDE): Pioneering the Detection of Rare Nuclear Decays and Exotic Dark Matter

The Global Rare Anomalous Nuclear Decay Experiment (GRANDE) aims to push the frontiers of nuclear and modern physics through the experimental measurement of rare nuclear decays. A key focus of GRANDE is the search for exotic dark-matter particles, including axion-like particles, anapole dark matter, and dark photons in nuclear transitions. Based on observations of rare electron-capture decay branching of 57Co and 139Ce isotopes, the potential detection of mimic dark-matter particles in underground experiments is theoretically promising [1].
This work presents the innovative research and development of a Cerium Bromide (CeBr3) detector, specifically designed for this mission, conducted at the Yemi Underground Lab, Korea. The detector employs a source-as-detector technique utilizing 57Co and 139Ce isotopes. The CeBr3 scintillation crystal, known for its rapid decay time, high light yield, excellent energy resolution, and high density, is ideally suited for detecting low-energy events and utilizing time-tag techniques.
In GRANDE, we have successfully fabricated and developed CeBr3 source-detector scintillation crystals using the Bridgman technique, incorporating radiation source doping to embed radiation sources within the crystal lattice. The integration of a 4π veto system is considered to enhance performance and detection limits. A 5x5x7.5 cm3 Bismuth Germanate (BGO) crystal is tested for this task. The electronic for data acquisition have been considered for this mission with the capability of time decay coincidence technique to eliminate backgrounds, particularly in isomeric state measurements, thus enabling precise photon identification.
To achieve accurate measurements of rare decay processes, a zero-background environment is essential. Therefore, GRANDE is divided into two stages: the first stage involves understanding and enhancing the radiation background. At the Yemi Underground Lab, we investigated the background levels of the detector and shielding setup using a ϕ1x1 inch pure CeBr3 detector to study internal and external backgrounds. Enhancements were made to achieve a suitable radiation background for dark matter search. The second stage focuses on source-as-detector measurements. We will present the fabrication and measurement R&D of our detector setup, highlighting results and detailed experiments from this pioneering effort in rare nuclear decay and dark matter detection.
[1] A. Anihotri, J. Suhonen, H.J. Kim, “Constraints for rare electron-capture decays mimicking detection of dark-matter particles in nuclear transitions”, Physical Review Letters 1333 (2024) 232501.

Speaker: Prof. Hong Joo Kim (Department of Physics, Kyungpook National University, Korea)

Presentation_ID293_Kim.pptx

219 Searching for the Anomalous Internal Pair Creation in $^8$Be

In 2016, the announcement of an anomaly in the Internal Pair Creation (IPC) in the isoscalar magnetic dipole transition in $^8$Be [1] triggered an effort worldwide to investigate this phenomenon. According to the model of Rose for the IPC process [2,3], the $e^+e^-$ angular correlation distribution drops quickly with the $e^+e^-$ relative angle. In contrast, a peak-like behavior was observed at around 140$^{\circ}$. This result was interpreted as the creation and subsequent decay of a previously unknown neutral boson, named X(17), with a mass of $m_o c^2 = 16.7 \pm 0.35(stat)$~MeV.

At the Laboratori Nazionale di Legnaro (LNL-INFN), a new $e^+e^-$ pair spectrometer was built and commissioned. The EJ2000 (polyvinyl toluene) scintillator material was used in its construction. The project aims to measure the angular correlation distribution of the $e^+e^-$ pairs from the IPC process in light nuclei. In 2023 and 2024, the first experimental campaign occurred at the AN2000 accelerator facility at LNL-INFN. LiF targets were irradiated to study the proton-induced nuclear reactions $^7$Li($p$,$e^+e^-$)$^8$Be and $^{19}$F($p$,$\alpha e^+e^-$)$^{16}$O. The $1^+_1 \rightarrow 0^+_1$ and $1^+_2 \rightarrow 0^+_1$ electromagnetic transitions in $^8$Be were been studied. The interest in those transitions lies in that anomalies have been reported [1,4]. In addition, the $0_2^+ \rightarrow 0^+_1$ electromagnetic transition has been taken as a reference due to the high $e^+e^-$ emission. This work reports the first results of this experimental campaign, providing a panorama of the new opportunities for studying the IPC process using this new $e^+e^-$ pair spectrometer.

[1] F.W.N. de Boer et al, Phys. Let. B
[2] E. Rose, Phys. Rev. 76 (1949) 678.
[3] E. Rose, Phys. Rev. 78 (1950) 184.
[4] J. Krasznahorkay et al., Phys. Rev. Let. 116 (2016) 7.

Speaker: Benito Gongora Servin (University of Padova)

Presentation_ID413_Gongora.pptx

220 Study of the $^{50}$V forbidden beta decay using a multi-channel HPGe detector at the underground laboratory

$^{50}$V is one of the high-order forbidden beta decay isotopes of interest in nuclear physics due to its extremely rare decay process. The decays of 50V to the ground states of $^{50}$Ti and $^{50}$Cr are classified as fourfold forbidden decays involving a significant spin change (ΔJ=6).
Notably, the beta decay mode transitioning to 50Ti has never been observed, and its half-life is known only as an upper limit. Based on theoretical calculations using the shell model, the half-life of the beta decay of 50V is estimated to be about 2 $\times$ 10$^{19}$ years, while the latest limit value is reported to be 1.9 $\times$ 10$^{19}$ years (90% C.I.) at the Gran Sasso Underground Laboratory (LNGS).
The Center for Underground Physics (CUP) in Korea has the CAGe (CUP Array of HPGe Detectors), an array of 14-channel HPGe detectors designed for high-sensitivity measurements in rare event physics research. Research on the decay of 50V has been conducted using CAGe, with a purified vanadium metal sample weighing 788 grams which used in 2019 at the LNGS.
Preliminary results from the first run, which involved approximately 100 days of data collection, were recently obtained. The initial results will be reported in this talk.

Speaker: Gowoon Kim (Center for Underground Physic, IBS)

Presentation_ID519_Kim.pdf

Parallel Session: 4_Nuclear Structure (2)

Convener: Vittorio Somà (CEA Saclay)

221 QCD-based approach on isospin symmetry breaking energy density functional

The isospin symmetry of atomic nuclei is broken due to the Coulomb interaction and the isospin symmetry breaking part of the nuclear interaction. The former gives the dominant contribution to the isospin symmetry breaking of atomic nuclei, and the latter is a small part of the whole; however, it sometimes gives important contributions to nuclear properties, such as the mass difference of mirror nuclei and the isobaric analog states [1, 2]. Especially, it has been a long-standing problem that the Coulomb interaction is not enough to describe the mass difference of mirror nuclei, which is known as the Okamoto-Nolen-Schiffer anomaly [3, 4], and some other properties [2].

The isospin symmetry breaking can be classified into two parts: the charge symmetry breaking (CSB) and the charge independence breaking (CIB). The CSB originates from the mass difference between protons and neutrons and rho-omega and pi-eta mixing in the meson exchange picture and the CIB originates from mass difference between charged pions and neutral ones. These origins are related to the mass difference of up- and down-quarks. Therefore, it is related to the fundamental study on the quarks and strong interaction; for instance, it is indispensable to estimate the isospin symmetry breaking of nuclear interaction properly to test the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.

The CSB term of the effective interaction, i.e., the energy density functional (EDF), can be determined phenomenologically based on experimental data [1, 5] or theoretically based on ab initio calculation. However, we found that the CSB strength determined phenomenologically is about ten times larger than that by ab initio calculation [6]. Therefore, we have pin down the isospin symmetry breaking terms of the EDF based on more fundamental theory.

We pinned down the CSB EDF using the effective mass in medium of nucleons calculated based on the quantum chromodynamics sum rule [7]. We found that the QCD-based CSB EDF can reproduce experimental data of the mass difference of mirror nuclei of $ N = Z \pm 1 $ nuclei quite nicely. We also estimated the CIB term of the EDF based on the quantum electrodynamics effects in the one-pion exchange potential (OPEP) [8], where we can, in principle, consider the effective mass of pions in medium. We found that even without the in-medium effect of pions, the OPEP-based CIB EDF can reproduce the CIB contribution to the equation of state obtained phenomenologically.

In this talk, I will report our recent progress on the derivation of the isospin symmetry breaking energy density functional based on quantum chromodynamics.

References
[1] X. Roca-Maza, G. Colò, and H. Sagawa. "Nuclear Symmetry Energy and the Breaking of the Isospin Symmetry: How Do They Reconcile with Each Other?" Phys. Rev. Lett. 120, 202501 (2018).
[2] T. Naito, G. Colò, H. Liang, X. Roca-Maza, and H. Sagawa. "Effects of Coulomb and isospin symmetry breaking interactions on neutron-skin thickness" Phys. Rev. C 107, 064302 (2023).
[3] K. Okamoto. "Coulomb energy of $ \mathrm{He}^3 $ and possible charge asymmetry of nuclear forces" Phys. Lett. 11, 150 (1964).
[4] J. A. Nolen, Jr. and J. P. Schiffer. "Coulomb energies" Annu. Rev. Nucl. Sci. 19, 471 (1969).
[5] P. Bączyk, J. Dobaczewski, M. Konieczka, W. Satuła, T. Nakatsukasa, and K. Sato. "Isospin-symmetry breaking in masses of $ N \simeq Z $ nuclei" Phys. Lett. B 778, 178 (2018).
[6] T. Naito, G. Colò, T. Hatsuda, H. Liang, X. Roca-Maza, and H. Sagawa. "Possible inconsistency between phenomenological and theoretical determinations of charge symmetry breaking in nuclear energy density functionals" Nuovo Cim. C 47, 52 (2024).
[7] H. Sagawa, T. Naito, X. Roca-Maza, and T. Hatsuda. "QCD-based charge symmetry breaking interaction and the Okamoto-Nolen-Schiffer anomaly" Phys. Rev. C 109, L011302 (2024).
[8] T. Naito, G. Colò, T. Hatsuda, X. Roca-Maza, and H. Sagawa. To be submitted.

Speaker: Dr Tomoya Naito (RIKEN iTHEMS)

Presentation_ID160_Naito.pdf

222 Proton-neutron pairing in the fp-shell via the 48Cr(p,3He)46V transfer reaction

Unlike standard like-particle pairing (neutron-neutron, proton-proton) that exists only in the T=1 channel, proton-neutron pairing can exist in both the T=1 and T=0 channels. This coexistence could explain phenomena such as the overbinding of self-conjugate nuclei.

Proton-neutron pairing can be studied by spectroscopy as in ref. [1], or by transfer reactions, as in ref. [2], since the two-nucleon transfer reaction cross section is expected to be enhanced by pairing. The relative proton-neutron T=1 and T=0 pairing strengths can be accessed by measuring transfer cross sections to the low-lying (J=0$^+$, T=1) and (J=1$^+$, T=0) states in odd-odd N=Z nuclei. The (p,$^3$He) reaction can be used, as its selection rules allow to populate both states at once.

As pairing is a collective effect, it is expected to be stronger in the middle of high j orbitals. The f$_{7/2}$ shell is the highest j shell currently accessible with sufficient beam intensity for two-nucleon transfer reactions in N=Z nuclei. The nucleus $^{48}$Cr, lying at the middle of this shell, has been selected for study and will be compared with previous experiments in the same region [2]. Moreover, $^{48}$Cr is a good candidate for exploring the interplay between pairing correlations and deformation, as it is known to be a good rotor up to spin 10$^+$ [3].

The experiment to measure the two-nucleon transfer reaction $^{48}$Cr(p,$^3$He)$^{46}$V was performed in 2023 at GANIL. A radioactive $^{48}$Cr beam at 30 MeV/u was produced by fragmentation of a primary $^{50}$Cr beam and selected by the LISE spectrometer, before impinging on a CH$_2$ target. A forward array of DSSD-CsI telescopes (MUGAST) was used to identify light charged particles and reconstruct the excitation energy, and was coupled to 12 EXOGAM Germanium clovers around the target, a Zero Degree Detection (ZDD) and MWPC detectors to reconstruct event by event the beam position on the target.

I will present preliminary absolute cross sections and cross section ratios, and angular distributions for the low-lying states of $^{46}$V. They will be compared with second-order distorted wave Born Approximation (DWBA) calculations for two-nucleon transfer performed with both realistic and single particle two-nucleon amplitudes (TNA). The results will be put in perspective with theoretical models and the systematics in the f-shell : $^{56}$Ni(p,$^3$He), $^{52}$Fe(p,$^3$He) and $^{40}$Ca(p,$^3$He).

[1] Cederwall, B., Moradi, F., Bäck, T. et al. Evidence for a spin-aligned neutron-proton paired phase from the level structure of $^{92}$Pd. Nature 469, 68-71 (2011). https://doi.org/10.103/nature09644

[2] Le Crom, B., Assié, M., et al. Neutron-proton pairing in the N=Z radioactive fp-shell nuclei $^{56}$Ni and $^{52}$Fe probed by pair transfer, Physics Letters B 829 (2022), 137057. https://doi.org/10.1016/j.physletb.2022.137057

[3] Robinson, S. J. Q. and Hoang, T. and Zamick, L. and Escuderos, A. and Sharon, Y. Y. Shell model calculations of $B(E2)$ values, static quadrupole moments, and $g$ factors for a number of $N=Z$ nuclei. Phys. Rev. C 89 (2014), 014316. https://link.aps.org/doi/10.1103/PhysRevC.89.014316

Speaker: Hugo Jacob (Université Paris-Saclay, IJCLAB, CNRS)

Presentation_ID383_Jacob.pdf

223 The beta-decay properties of N=Z nuclei: Role of neutron-proton pairing and the shell model interpretation

The structure and decay properties of neutron-deficient nuclei along the $N=Z$ line have been one of the most important focal points of nuclear physics studies. An essential feature of nuclear structure that can affect the $\beta$ decay of $N=Z$ nuclei is the pairing correlation [1,2]. From the recent experimental measurement [3], an enhancement in GT transition strength for the $\beta$-decay of $^{70}$Br in comparison to the decay of $^{62}$Ge was observed, which was suggested as an indication of increased np pairing. Along the $N=Z$ line, we have performed detailed shell model calculations for four different transitions: $^{58}$Zn (0$^+_{\rm g.s.}$) $\rightarrow$ $^{58}$Cu, $^{62}$Ge (0$^+_{\rm g.s.}$) $\rightarrow$ $^{62}$Ga, $^{66}$Se (0$^+_{\rm g.s.}$) $\rightarrow$ $^{66}$As, and $^{70}$Kr (0$^+_{\rm g.s.}$) $\rightarrow$ $^{70}$Br. The purpose of this work is to study the GT decays to odd-odd $N = Z$ nuclei and identify the role played by the isovector as well as isoscalar np interactions.

First, we have determined the impact of pairing on GT transitions using the surface delta effective interaction with only $J=1, T=0$ and $J=0, T=1$ pairing matrix elements in the model space $p_{3/2}p_{1/2}f_{5/2}$. Even though the interaction is relatively simple, it gives a precise control on the phases of different components of the wave function and separates contributions from different single-particle orbitals to the total $B_{\rm GT}$. Based on the results, we can conclude that the $B_{\rm GT}$ between yrast $0^+$ and $1^+$ states doesn't necessarily increase with increasing np pairing strength. That is partly due to the fact that the GT transitions are highly selective and only connect states with the same $l$ value. Further, we have extended our model space by including $g_{9/2}$ orbital and performed the schematic calculations in $f_{5/2}pg_{9/2}$ model space. With the inclusion of the $g_{9/2}$ orbital, the GT strength can be increased with increasing np pairing in connection with the enhanced contribution from the $g_{9/2}$ orbital.

We have compared the schematic results with realistic calculations in the $fp$ and $f_{5/2}pg_{9/2}$ model space, to gauge the contribution from $f_{7/2}$ and $g_{9/2}$ orbitals in the GT strengths. With JUN45 interaction [4], there is an increment for yrast $1^+$ state for the decay of $^{70}$Kr as compared to the decay of $^{62}$Ge due to increased $g_{9/2}$ contribution. The total accumulated $B_{\rm GT}$ strength increases for GXPF1J interaction [5]. Additionally, we investigate the effect of np pairing on $B_{\rm GT}$ by modifying the single-particle energies and the $T = 0$ matrix elements of the interaction responsible for the decay transition strength. We found an increment in cumulative GT transition strength with increased np pairing matrix elements using GXPF1J interaction. The accumulated $B_{\rm GT}$ strengths are rather well reproduced but the decay to the low-lying states can be sensitive to the contributions from the deep-lying $f_{7/2}$ and higher-lying $g_{9/2}$ orbitals.

[1] B. Cederwall et al., Nature 469, 68 (2011).
[2] S. Frauendorf et al., Progress in Particle and Nuclear Physics 78, 24 (2014).
[3] A. Vitéz-Sveiczer et al., Physics Letters B 830, 137123 (2022).
[4] M. Honma et al., Phys. Rev. C 80, 064323 (2009).
[5] M. Honma et al., Journal of Physics: Conference Series 20, 7 (2005).

Speaker: Priyanka Choudhary (KTH Royal Institute of Technology)

Presentation_ID325_Choudhary.pdf

224 The decay of Tz=-1 fp shell nuclei

The decay of Tz=-1 fp shell nuclei
B. Rubio for the GSI_GANIL_RIKEN collaboration
IFIC (CSIC-Uni. Valencia), Spain

In this talk, I plan to present an overview of recent studies on the + decay of Tz=−1 nuclei in the fp-shell. The overview includes campaigns conducted at GSI, GANIL, and RIKEN. These experiments were carried out at fragmentation facilities using high-intensity primary beams, high-performance recoil separators, and advanced detector techniques. The experimental setup features charged particle detectors and gamma-ray Germanium (Ge) arrays. All the decays are very fast due to the involvement of super-allowed Fermi (F) transitions and allowed Gamow-Teller (GT) transitions. The experiments yielded rich spectroscopic data, enabling comparisons along the near-N=Z line. Several interesting phenomena can be studied, such as:
1. Mirror symmetry effects: These are explored by comparing + decays with the mirror charge-exchange reactions on stable Tz=+1 nuclei targets. (Y. Fujita, B. Rubio, W. Gelletly, Progr. Part. Nucl. Phys. 2011, 66, 549–606)
2. SU(4) symmetry interpretation: Possible insights into the decays based on SU(4) symmetry. (Van Isacker et al. Symmetry 2023, 15(11), 2001)
3. Theoretical calculations: Including these Fermi transitions in theoretical calculations for super-allowed ft-values and their implications for Vud matrix element and CKM matrix unitarity. (I. S. Towner and J. C. Hardy, Phys. Rev C 92, 055505 (2015))

Overview of the Tz=-1 beta decaying cases discussed in this work, references below

1. 42Ti-54Ni (GSI)
   Molina et al. Phys. Rev. C 91, 014301 (2015)
2. 56Zn (GANIl and RIKEN)
   Kuckuc et al Eur. Phys. J. A 2017, 53, 134-1–10
   DOI 10.1140/epja/i2017-12327-1
   Nishimura et al. in preparation
3. 60Ge (RIKEN)
   Orrigo et al. Phys. Rev. C 2021, 103, 014324-1–12.
4. 64Se (RIKEN)
   Aguilera et al. in preparation
5. 70Kr (RIKEN)
   Vitéz-Sveiczer et al. Phys. Lett. B 2022, 830, 137123-1–8.

Speaker: Berta Rubio (IFIC (CSIC- Uni Valencia))

Presentation_ID214_Rubio_v6.pptx

225 Superallowed Alpha Decay of 104Te

The double-magic nature of $^{100}$Sn generates the island of $\alpha$-emitters northeast of this N=Z=50 nucleus. The increase of energy-corrected $\alpha$-decay probabilities was considered to be a signature of enhanced $\alpha$ particle preformation and led to the term "superallowed" $\alpha$ decay for nuclei in the region [1]. The N=Z=52 $^{104}$Te is predicted to be the fastest $\alpha$ emitter. Auranen et al. measured $^{104}$Te and found that it is likely a very short-lived nucleus characterized by much-increased preformation, even compared to other nuclei in the region [2]. Due to the limited statistics, the authors could only place an upper limit on the half-life based on the measurement of the decay chain of $^{108}$Xe. Here, we will report the results of the direct measurement of the $^{104}$Te half-life. We used a fast-response, scintillator-based charged-particle detector to measure the decay of $^{108}$Xe, which populates $^{104}$Te. We utilized the projectile fragmentation of a high-intensity $^{124}$Xe beam at RIKEN Radioactive Ion Beam Factory (RIBF) to produce the most $^{108}$Xe nuclei to date. This work will present the experiment's results in the context of the numerous theoretical predictions for the decay of $^{104}$Te.

[1] R. Macfarlane and A. Siivola, Phys. Rev. Lett. 14, 144 (1965)
[2] K. Auranen, et al. Phys. Rev. Lett. 121, 182501 (2018)

This work was supported by US DOE No. DE-FG02-96ER40983 and NNSA No. DE-NA0003899

Speakers: Robert Grzywacz (University of Tennessee), Robert. K Grzywacz (University of Tennessee, Knoxville, ORNL)

Presentation_ID106_Grzywacz.pdf

Parallel Session: 4_Nuclear Structure (3)

Convener: Youngman Kim (CENS, IBS)

226 Structure within the N=40 Island of Inversion

The focus of this work is neutron-rich Fe and Mn isotopes with N~40, which lie within an Island of Inversion approximately centered at ⁶⁴Cr. Here, a quenching of the N=40 sub-shell gap allows multi-particle, multi-hole excitations and deformation to develop in the ground-state configurations of nuclei in the region. Limited spectroscopic information has been collected so far in the region of N~40 below ⁶⁸Ni. For the even-even nuclei, the 2⁺₁ and 4⁺₁ state energy systematics has been explored and, for the Fe and Cr isotopes, of B(E2; 2⁺₁->0⁺₁) values have been measured up to ⁶⁸Fe and ⁶⁴Cr. Large-scale shell model (LSSM) calculations well reproduce the energy systematics of the observed low-lying states of the even-even Fe and Cr isotopes around N=40. However, spectroscopic factor and more complete level scheme predictions in the region have not yet been benchmarked by experimental results.

Proton knockout reactions on the neutron-rich N=38 and N=40 isotopes ^64,66Fe and ^63,65Mn have been performed to investigate the proton spectroscopic factors of the parent nuclei. We will discuss the results of this measurement as well as a complementary secondary fragmentation measurement, and interpret in comparison with both LSSM and Nilsson model calculations.

Speaker: Heather Crawford (Lawrence Berkeley National Laboratory)

Presentation_ID627_Crawford.pdf

227 Probing the island of inversion at N=40 through beta-decay of Mn isotopes

One of the best-known divergences from the independent-particle shell model description of the atomic nucleus is the existence of islands of inversion [1]. The IoI of the region N=40 draws particular attention since the neutron number 40 was postulated as a non-traditional “magic” number and N = 40 represents the boundary between the pf and g shells.
Measurements of B(E2) values and E(2+) in the neutron-rich region show increased collectivity through the N = 40 shell gap, with the clear exception of 68Ni [2,3]. Deformation and shape coexistence have been identified in the area and RIKEN experiments suggest the N=40 IoI extends toward N=50, paralleling the merging of N=20 and N=28 IoIs. LNPS calculations predict triple shape coexistence for 67Co (N=40), with three rotational bands [4]. And recent experiments on 67Fe (N=41) propose a spin-parity of 5/2+ or 1/2− for its ground state [5] which indicates a significant deformation. In addition, shape coexistence is also expected for 67Fe.
Detailed spectroscopic information of the iron, cobalt, and nickel isotopes is crucial to accurately mapping the transition to the N = 40 island of inversion and serves as a test for accuracy of theories. However, very limited information is available, so to this end, an experiment was performed at the TRIUMF-ISAC facility utilizing the GRIFFIN spectrometer [6], where the β and βn decay of 69Mn, 68Mn, and 67Mn, populates the corresponding Fe, Co and Ni isotopes. This data set contains orders of magnitude more statistics than previous studies allowing us to build for the first time a complete level scheme of 68Fe and 67Fe and to improve upon the known β- decay level schemes of 67Co, by expanding the number of transitions and levels, as well as by improving the precision of branching ratios and ground-state half-life measurement. In addition, measurements of level lifetimes down to the picosecond range will allow us to investigate the band structure in these nuclei. For the 67Fe isotope, the good level of statistics will make it possible to measure the energy of the identified isomeric state and improve the lifetime measurement. These results can provide further insight into the detailed structure of the states by comparison to simple models and large-scale shell model calculations in order to confirm or refute the shape coexistence picture predicted by LNPS calculations and the shrinking of the N=40 gap just one proton below 68Ni.
[1] B. A. Brown. Physics, 3:104 (2010).
[2] S. Naimi et al.,Phys. Rev. C 86 (2012), p. 014325
[3] M. Hannawald et al., Phys. Rev. Lett. 82 (1999), pp. 1391–1394.
[4] F. Recchia et al.,Phys. Rev. C, 85:064305 (2012)
[5] M. Sawicka et al., The European Physical Journal A - Hadrons and Nuclei, 16(1):51–54, 2003
[6] Garnsworthy et al., Nucl. Inst. Meths. A 918, 9 (2019)

Speaker: Dr Victoria Vedia (TRIUMF/CERN)

Presentation_ID695_Vedia.pdf

Presentation_ID695_Vedia.pptx

228 High-precision TDRIV g-factor measurement in 22Ne and its implications for the N=20 Island of Inversion

The Island of Inversion in the neutron-rich $N=20$ region arises in part due to a significant reduction in the energy gap between the sd and fp shells. Recent theoretical calculations [1] and experimental results in $^{30}$Mg [2] favor a much smoother transition towards the Island of Inversion than previously thought, with considerable fp admixtures in the ground state of $^{30}$Mg and small fp admixtures down to $^{28}$Mg. If such admixtures are present already in $^{28}$Mg, they are expected to influence the g factor of its $2^+_1$ state as the magnetic dipole moments are especially sensitive to the mixing of single-particle configurations.

To test this hypothesis, the first application of the Time Differential Recoil In Vacuum (TDRIV) method [3,4] on a radioactive ion beam aimed to measure the g factor of the $2^+_1$ state in $^{28}$Mg. The experiment was carried out at HIE-ISOLDE in 2017 using the MINIBALL HPGe detector array, a CD DSSSD for particle detection and the MINIBALL plunger device, and the state of interest was populated via Coulomb excitation of the post-accelerated $^{28}$Mg beam. The TDRIV method is based on observing the Larmor frequency, proportional to the g factor, at which the nuclear and atomic spins precess around the total spin of the projectile as it recoils between the target and a secondary foil within a plunger device. In the same experiment a calibration TDRIV measurement of the supposedly well-known g factor of the $2^+_1$ state in $^{22}$Ne was also performed as a test of the plunger system and in order to determine the plunger zero-offset distance, needed to constrain the $^{28}$Mg TDRIV analysis. A striking disagreement was observed between the newly-obtained results from the $^{22}$Ne measurement and the adopted g-factor value from the 1970s [5], which introduced significant systematic uncertainties for the $^{28}$Mg g-factor result.

In order to reduce the systematic uncertainties of the $^{28}$Mg measurement and to resolve the discovered discrepancy in $^{22}$Ne an experiment to re-measure the g factor of the $2^+_1$ state in $^{22}$Ne was performed in September 2024 at GANIL. The experimental setup consisted of the EXOGAM $\gamma$-ray spectrometer coupled to the Orsay Universal Plunger System and the newly-developed Orsay Particle Scintillator Array (OPSA). With the provided $10^9$ pps $^{22}$Ne beam intensity we were able to collect high-statistics particle-$\gamma$ coincidence data that will allow us to obtain a high-precision and high-accuracy value for the g factor of the $2^+_1$ state in $^{22}$Ne. The results from the preliminary analysis of this data set will be presented and compared to theoretical predictions. In addition, the implications of these results on the $^{28}$Mg g-factor measurement from ISOLDE, and on the extent of the $N=20$ Island of Inversion will be discussed.

Speaker: Konstantin Stoychev (University of Guelph, Canada)

Presentation_ID200_Stoychev.pdf

229 Mixing between single particle and intruder states towards the N=20 island of inversion: lifetimes in 37S

The disappearance of the N=20 shell closure in the so-called “island of inversion” around $^{32}$Mg is one of the most striking examples of the strength of nucleon-nucleon correlations. In this region, the quadrupole-deformed intruder configuration (based on a multi-particle multi-hole configuration) becomes the ground state, subverting the expected shell ordering predicted by a harmonic oscillator plus spin-orbit term. The odd N=21 isotonic chain provides the possibility to study the single-particle and intruder states as a function of decreasing Z. Available spectroscopic evidence points out the appearance of strong branching ratios among the single-particle and collective intruder configurations in $^{37}$S (Chapman et al, Phys. Rev. C, 93 044318 (2016)), suggesting that they mix significantly, contrary to the notion of $^{37}$S being well out the island of inversion. However, a precise quantification of this phenomenon in terms of transition strength is still lacking. The first excited state (3/2$^{-}$ state at 646 keV) is the only one with a measured lifetime (Wang et al., Phys. Rev. C, 94 044316 (2016).), but no transition probability has been firmly determined for the intruder states, in particular those decaying to the \textit{a priori} spherical single-particle states.
A combined DSAM+RDDS measurement has been performed to measure such transition probabilities, in particular for the 2p-1h 3/2$^{+}$ state at 1397 keV and the 3p-2h 7/2$^{-}$ at 2023 keV, exploiting the performance of the AGATA spectrometer in terms of energy and angular resolutions. The $^{37}$S nucleus has been produced via the $^{36}$S(d,p) reaction in inverse kinematics, detecting the recoiling protons in the silicon array SPIDER to obtain an accurate reconstruction of the excitation energy of $^{37}$S. The short lifetimes measured point to large M1 and/or E2 strengths connecting the intruder and spherical states. This would imply a significant mixing between the configurations, arising questions about the determination of the neutron p$_{3/2}$-p$_{1/2}$ single-particle strength distribution in $^{37}$S.

Speaker: Luca Zago (University of Milano "La Statale" and INFN-LNL)

Presentation_ID665_Zago.pdf

230 β-decay of $^{68}$Mn: Probing the N=40 island of inversion

Although the shell model is fundamental to our understanding of nuclear structure, the breakdown of traditional magic numbers far from stability provides insight into the nature of the underlying nuclear interactions and acts as a tool to test existing models. Islands of inversion (IoI) in the nuclear landscape are characterized by the presence of deformed multi-particle multi-hole (npnh) ground states instead of the (0$\textit{p}$0$\textit{h}$) configurations predicted by spherical mean-field calculations. This is typically driven by the strong nuclear quadrupole-quadrupole interaction that induces shape transitions, wherein these highly correlated "intruder" states become more bound than spherical ones.

In the N=40 region, the relatively large energy gap separating the pf shell from the $\nu$$\textit{g}_{9/2}$ orbital points towards a strong sub-shell closure at N=40 which has been supported by the observation of a high-lying 2$^{+}$ state and low $\textit{B}$($\textit{E}$2) value in $^{68}$Ni (Z=28) [1]. However, systematics of $\textit{E}$(2$^{+}$) and $\textit{B}$($\textit{E}$2) values have indicated a sudden increase in collectivity below Z=28 when approaching N=40, seen especially in the rapid drop of $\textit{E}$(2$^{+}$) in Fe (Z=26) and Cr (Z=24) isotopes [2,3]. This increase in collectivity is thought to be due to the neutron occupation of intruder states from a higher shell, similar to the IoI around N=20 [4,5].

Shape coexistence also manifests in nuclei at the boundaries of IoIs [6]. In the N=40 region, low-lying 0$^{+}$ excited states, which are traditional indicators of shape coexistence have been identified up to A=66 [7,8]. In $^{68}$Fe, a state at 2035 keV is tentatively assigned as 0$^{+}$ or 2$^{+}$ and the confirmation of this spin would indicate whether this trend extends past N=40. Recent studies also suggest the occurrence of a new IoI at N=50 and a proposed merging of the N=40 and N=50 IoIs, equivalent to the one observed between N=20 and N=28 [9,10,11].

To explore these phenomena, an experiment was performed at TRIUMF-ISAC using the GRIFFIN spectrometer that utilized the $\beta$- and $\beta$n decay of $^{68}$Mn to populate excited states in $^{67,68}$Fe, $^{67,68}$Co and $^{67,68}$Ni. This experiment produced the highest-statistics data set to date for these isotopes. Consequently, we have greatly expanded the level scheme of $^{68}$Fe and measured key observables such as $\gamma$-ray intensities and branching ratios. A comprehensive level scheme of $^{67}$Fe populated through the $\beta$n decay has been established for the first time along with a re-measurement of the P$_{n}$ value. Angular correlation analysis, which will provide firm assignments of spins and parities of low-lying excited states, is underway. We have new information on the spin assignment of the 2035 keV level in $^{68}$Fe which leads to a reinterpretation of shape coexistence in this nucleus. This, along with other preliminary results, will be presented and discussed.

[1] O. Sorlin et al. In: Phys. Rev. Lett. 88 (9 Feb. 2002), p. 092501.
[2] S. Naimi et al. In: Phys. Rev. C 86 (1 July 2012), p. 014325.
[3] M. Hannawald et al. In: Phys. Rev. Lett. 82 (7 Feb. 1999), pp. 1391–1394.
[4] S. M. Lenzi et al. In: Phys. Rev. C 82 (5 Nov. 2010), p. 054301.
[5] Y. Tsunoda et al. In: Phys. Rev. C 89 (3 Mar. 2014), p. 031301.
[6] M. Rocchini et al. In: Phys. Rev. Lett. 130 (12 Mar. 2023), p. 122502.
[7] Balraj Singh. In: Nuclear Data Sheets 108.2 (2007), pp. 197–364.
[8] S. N. Liddick et al. In: Phys. Rev. C 87 (1 Jan. 2013), p. 014325.
[9] C. Santamaria et al. In: Phys. Rev. Lett. 115 (19 Nov. 2015), p. 192501.
[10] E. Caurier, F. Nowacki, and A. Poves. In: Phys. Rev. C 90 (1 July 2014), p. 014302.
[11] F. Nowacki et al. In: Phys. Rev. Lett. 117 (27 Dec. 2016), p. 272501.

Speaker: Ms Rashmi Umashankar (TRIUMF)

Presentation_ID88_Umashankar.pptx

231 Spectroscopic study of the unnatural parity levels in 49V

The study of the 1f7/2-shell nuclei gives us a unique opportunity to investigate the interplay between single particle and collective excitations. Strong collectivity near ground state, rotational like band structure, shape transitions towards triaxial and non-collective deformations in the natural (positive for even nuclei and negative for odd nuclei) parity bands have been observed in 48Cr and in a few nuclei around 48Cr and interpret them successfully through shell model calculations [1]. However, the spectroscopic investigations for the unnatural (negative for even nuclei and positive for odd nuclei) parity bands are limited.
The level scheme of the unnatural (positive) parity levels in 49V was extended up to the band terminating state, Jπ = (31/2+). However, the spins and parities of levels above the 11/2+ level were not confirmed and the lifetime data are only available up to the 11/2+ level with large uncertainties (> 100% in some cases) [2]. It was, therefore, felt necessary to re-measure them in order to corroborate the available spectroscopic data and to expand them to include information on high spins.
49V, populated through 48Ti(4He, 2np)49V reaction with 48 MeV 4He beam at VECC Kolkata, was studied very recently by our group using INGA facility, focusing on its natural (negative) parity levels [3]. The present work is an extension to include the results for a few unnatural parity levels. From the analysis, two positive parity signature partner bands were confirmed in 49V and two new γ’s linking these bands were found. In addition, the lifetimes of four levels were measured for the first time, and the lifetimes of two other levels were remeasured to validate our measurements. Multipole mixing ratio (δ) of a few dipole transitions was also measured. Large basis shell model (LBSM) calculations were performed using the code NUSHELLX [4] and SDPFMWPN [5] interaction to interpret the experimental observation. In the calculation only one particle (either proton or neutron) is allowed to excite from the 1d3/2 to the particle restricted pf orbitals. Calculated energies and the transition strengths agreed well with the corresponding experimental values. Based on the measured lifetimes, calculated wave functions and the Qs values, evolution of nuclear shape with angular momentum has been established.

[1] S. M. Lenzi, Phys. Rev. C 56, 1313 (1997); N. H. Medina et. al., Heavy Ion Physics 16, 65 (2002); J. A. Cameron et. al., Phys. Rev. C 58, 808 (1998).
[2] D. Rodrigues et. al., Phys. Rev. C 92, 024323 (2015); B. Haas et. al., Phys. Rev. C 11, 1179 (1975).
[3] Y. Sapkota et al., Phys. Rev. C 105, 044304 (2022).
[4] NuShellX@MSU, B. A. Brown et. al., http://www.nscl.msu.edu/˜brown/resources/resources.html; NuShellX, W. D. M. Rae, http://www.garsington.eclipse.co.uk/.
[5] E. K. Warburton, J. A. Becker, and B. A. Brown, Phys. Rev. C 41, 1147 (1990).

Speaker: ABHIJIT BISOI (Indian Institute of Engineering Science and Technology Shibpur)

Presentation_ID77_BISOI.pdf

13:00 Lunch

Plenary Session: 2

Convener: Prof. Rituparna Kanungo (TRIUMF)

232 Expanding Opportunities for Discovery

The processes by which we foster curiosity, educate our youth, encourage people into science, recruit and retain people into physics and welcome them as members of our nuclear physics community are important in building a strong nuclear workforce for the future. Enabling the development of an identity as a scientist or nuclear scientist is a crucial part of mentoring young people to successful careers in nuclear science. Research experiences for students can play a critical role in that identity development.

Speaker: Sherry Yennello (Texas A&M University)

233 Status of Z=119 element search at RIKEN

Following the discovery of nihonium (Nh: Z=113), the RIKEN Nishina Center for Accelerator-Based Science (RNC) has started a new program aimed at producing additional new elements in the eighth period, the 119th and 120th, by hot fusion reactions. To achieve this goal, the RNC has upgraded a superconducting linac accelerator (SRILAC) and a superconducting ECR ion source to increase the beam intensity and the maximum acceleration energy. We have also constructed a new gas-filled recoil ion separator (GARIS-III) designed for the hot fusion reaction measurement [1]. Commissioning of these key devices was completed in 2019 and the $^{51}$V beam can now be accelerated up to 6.5 MeV/u.
Subsequently, a new collaboration, the 'nSHE collaboration,' was established, bringing together researchers from Japan, the USA, France, Poland, Australia, and China.
The experiment to synthesize element 119 is currently underway using a $^{51}$V+$^{248}$Cm $\rightarrow$ Z=119 reaction with a high-intensity beam. A highly enriched $^{248}$Cm$_2$O$_3$ material was provided to RNC under the Material Transfer Agreement between RNC and Oak Ridge National Laboratory.
In this presentation, we will report the current status of the experiment, highlighting the experimental setup, the methodology for determining the optimal reaction energy, and the progress toward detecting element 119.

[1] H. Sakai, H. Haba, K. Morimoto and N. Sakamoto, Eur. Phys. J. A. 58, 238 (2022).

Speaker: Kouji Morimoto (RIKEN, Nishina Center for Accelerator-Based Science)

163_Morimoto.pptx

163_Morimoto.pptx

163_Morimoto_final.pptx

163_Morimoto_final2.pptx

234 Probing the nature of neutrino

The nuclear beta decay revealed the existence of neutrino more than eight decades ago, but the neutrino still continues to be a puzzle waiting to be unravelled. The mass and nature of neutrinos play an important role in physics beyond the standard model. At present, neutrinoless double beta decay (NDBD) is perhaps the only experiment that can tell us whether or not the neutrino is its own antiparticle. Given the significance of the NDBD, there is a widespread interest worldwide employing a variety of novel techniques. This talk will present a brief overview of ongoing and proposed NDBD experiments and will highlight Indian efforts towards the feasibility study of search for NDBD in 124Sn.

Speaker: Prof. vandana nanal (Tata Institute of Fundamental Research)

Presentation_ID747_Nanal.pdf

Presentation_ID747_Nanal_web.pdf

16:00 Break

Plenary Session: 3

Convener: MinJung Kweon (Inha University)

235 Study the QCD Phase Structure in High-Energy Nuclear Collisions

The physics of strong interaction is described by the theory of Quantum Chromodynamics (QCD) which is part of the Standard Model. Since 2010, the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) has carried out beam energy scan (BES) program from the center of mass energy from 3 to 200 GeV corresponding to the baryon chemical potential 760 > μB > 25 MeV. The BES program has provided the most precise data of heavy-ion collisions over the widest range of beam energy for studying the QCD phase structure.

In this talk, I will report recent progresses in the RHIC BES program: the status of thermalization and the search for the QCD critical point including the measurements of collectivity, high moments of net-protons, hyper-nuclei production and baryon correlations in high-energy nuclear collisions. Finally, physics potentials with future facilities will be addressed.

Speaker: Prof. Nu Xu (CCNU)

Presentation_319_Xu.pdf

236 Hadrons in hot and dense matter

We summarize the relationship between chiral symmetry breaking and the masses of hadrons across various flavor representations. Next, we discuss the behavior of vector mesons in matter. Finally, we demonstrate why K1 and K* are appropriate chiral partners that can be realistically measured in experiments.

Speaker: Su Houng Lee (Yonsei University)

Presentation_ID452_Lee.pptx

237 Probing Dense Nuclear Matter by Heavy Ion Collision Experiments at NICA

Heavy-ion collisions offer a unique opportunity to study strongly interacting QCD matter under extreme conditions of temperatures and baryon densities. The main goal of this research has been to better understand the rich structure of the QCD phase diagram. The Nuclotron Ion Collider-fAcility (NICA) offers an opportunity to extend these studies to the range of ion collision energies from 2.4 to 11 GeV (center-of-mass) by providing high-luminosity scans both in collision energy and system size. The BM@N experiment at NICA has already taken data with argon and xenon beams, while commissioning of the MPD detector starts later this year.
In this talk, I will overview the status and the perspectives of the heavy ion research program at NICA. In particular, the recent results on hadron and light nuclei production as well as on collective flow from centrality selected Ar-nucleus and Xe-nucleus collisions at 3-4A GeV from the BM@N experiment will be discussed. The opportunities for future studies with the MPD experiment will be presented.

Speaker: Vadim Kolesnikov (JINR)

Presentation_ID540_Kolesnikov.pdf

238 New Insights into the Baryon Spectrum

We outline some of the new developments in our understanding of the baryon spectrum resulting from the simultaneous analysis of experimental data and lattice QCD, using Hamiltonian effective field theory.

Speaker: ANTHONY THOMAS (University of Adelaide)

Presentation_plenary 6pm Tuesday_Thomas.pdf

Poster Session

Wednesday, 28 May

Plenary Session: 4

Convener: Jenny Lee (The University of Hong Kong)

239 Nuclear structure around 132Sn from gamma-ray spectroscopy performed at RIBF

In recent years, significant progress has been made in the study of the
structure of atomic nuclei in the vicinity of doubly-magic 132Sn. In this
presentation, I will summarize the valuable contributions to this progress
made by in-beam and decay gamma-ray spectroscopy experiments performed
at RIBF (Tokyo, Japan). This includes studies of the shell evolution beyond
132Sn, both along the Z=50 and N=82 semi-magic chains, as well as new
insights into the isospin dependence of effective charges. Furthermore,
it will be discussed how complementary information obtained using inelastic
scattering on light and heavy targets and the DALI2+ and HiCARI gamma-ray
spectrometer allowed to investigate collective excitations in the vicinity
of 132Sn.

Speaker: Andrea Jungclaus (IEM-CSIC)

Presentation_ID443_Jungclaus.pdf

Presentation_ID443_Jungclaus.pptx

240 Novel microscopic approaches for Spin-Isospin excitations

The spin-isospin excitations including beta-decay may have strong impacts on the study of strong interactions in nuclear medium, and also the astrophysical phenomena such as the r-process nucleosynthesis together with the photonuclear cross sections, and the large-scale nucleosynthesis network calculations to create elements in the universe. In addition, the Gamow-Teller (GT) and spin-dipole (SD) resonances are
associated with double-beta decay processes, especially, for the zero-neutrino double-beta decay, which provides the information of neutrino-mass puzzle, and consequently the evidence beyond the standard model of elementary particles.

We explore extensively new and old, but still unsolved, nuclear structure problems induced by the spin and isospin degree of freedom
by using microscopic models which accommodate realistic isoscalar and isovector pairing interactions, and also tensor correlations [1].
For the attempt of universal theoretical framework for both nuclear and astrophysical phenomena, we adopt a self-consistent Hartree-Fock (HF)+random phase approximation (RPA) models embedded the tensor interactions [2], and a state-of-the-art beyond mean field model, Subtracted Second RPA (SSRPA) [3] including the couplings to two-particle two-hole (2p-2h) states.
Especially we study magnetic dipole (M1) [2,3], charge-exchange Gamow-Teller (GT) [1,3] and spin-dipole excitations. We mention also pigmy and giant resonances induced by the tensor interaction. Our results give a new insight on the quenching of GT sum rule strengths without introducing any free parameters in the self-consistent microscopic calculations. The SSRPA model is further applied to the
decay half-lives of four semi-magic and magic nuclei,
,
and
[3]. We show the inclusion of the 2p-2h configurations in SSRPA model shifts low-lying Gamow-Teller (GT) states downwards, and leads to an increase of the
decay phase space, and consequently reproduce the
decay half-lives dramatically close to the experimental observations. The effect of tensor interaction on the
decay half-life in SSRPA model is also pointed out to change largely the half-lives by about one to two orders of magnitude with respect to the ones obtained without tensor force.

We derived recently the charge symmetry breaking (CSB) EDF based on the QCD sum rule ap-proach [4]. We will discuss also the effect of QCD-based CSB on the double beta decay probabilities and eventually the neutrino mass puzzle.

References
[1] Eunja Ha, Myung-Ki Cheoun, and H. Sagawa, Prog. Theor. Exp. Phys. 2022, 043D01(2022); Prog. Theor. Exp. Phys. 2024, 063D02 (2024).
[2] Shuai Sun, Li-Gang Cao, Feng-Shou Zhang, Hiroyuki Sagawa, and Gianluca Colo, Phys. Phys. C109, 014321 (2024).

[3] M. J. Yang, H. Sagawa, C. L. Bai, and H. Q. Zhang, Phys. Rev. C 106, 014319 (2022) ; Phys. Rev. C 107, 014325 (2023).
[4] Hiroyuki Sagawa, Tomoya Naito, Xavi Roca-Maza, and Tetsuo Hatsuda, Phys. Rev. C109, L011302 (2024).

Speaker: HIROYUKI SAGAWA (RIKEN/University of Aizu)

Presentation_ID309_Sagawa-f.pptx

241 RI beam production studies at RAON facility

The Rare Isotope Accelerator complex for ON-line experiments (RAON) has the unique feature of utilizing both Isotope Separation On-Line (ISOL) and In-Flight (IF) fragmentation systems for the production of rare isotope beams, and the combined ISOL+IF method can produce rare isotope beams different from the one produced by either ISOL or IF technique.
How many RI beams we can produce in RAON facilities is crucial for designing experiments. Accurate estimates of the RI beam intensities are required, and production cross sections and momentum distributions are the important factors. There are many ways to estimate the production cross-section and many models are used to estimate the production cross-sections and momentum distribution, but their results are inconsistent. They usually can provide a good prediction of RI beam productions, however, in some regions of the nuclear chart such as the vicinity of driplines or when using the low-energy beam, their results are not consistent with reality. Therefore, measuring production cross-sections for RI beams is necessary to build more reliable models for RI beam productions. Their systematic trends can give us hints of production cross-sections of very neutron-rich nuclei.
In this talk, we will report the first experimental results at RAON with the measurement of the production rates and cross sections of RI beams around Oxygen isotopes using the 40Ar primary beam and graphite target. The systematics of production cross-sections and momentum distribution for produced RIs will be presented. In addition, the current studies and plans for the rare isotope beam productions in very neutron-rich nuclei at RAON using a two-step method will be discussed.

Speaker: Deuk Soon AHN (Center for Exotic Nuclear Studies, IBS)

INPC2025_DeukSoonAhn.pdf

242 Nuclear shape dynamics in low-energy heavy-ion reactions

It has been well known that nuclear collective excitations significantly affect heavy-ion reactions at energies around the Coulomb barrier in several different ways. One of the most well known examples is a large enhancement of fusion cross sections at subbarrier energies due to nuclear deformation. Nuclear deformation is relevant also to fusion for superheavy elements as well as reaction cross sections at intermediate energies. Recently, there have also been many discussions on relativistic heavy-ion collisions from a view point of a possible probe of nuclear deformation. In this contribution, I will discuss recent theoretical developments in low-energy heavy-ion reactions, putting emphasis on nuclear deformation. This includes, i) a new attempt to visualize nuclear scattering, ii) fusion of odd-mass systems, and iii) a shell model approach to nuclear shape dynamics in heavy-ion reactions. I will also discuss the role of nuclear shape dynamics with several adiabaticity, which would be important in discussing relativistic heavy-ion collisions.

Speaker: Kouichi Hagino (Kyoto University)

Presentation_ID333_hagino.pptx

10:30 Break

Plenary Session: 5

Convener: ANTHONY THOMAS (University of Adelaide)

243 Hidden charm pentaquarks with multiple strangeness

The discovery of the exotic heavy tetraquark state X(3872) by the Belle Collaboration and hidden charm pentaquarks ($P_{c\bar{c}}$) by the LHCb Collaboration marked a breakthrough in exotic hadron physics. Following these observations, numerous exotic hadrons have been found. Understanding their production mechanisms and internal multiquark structures will illuminate the fundamental origin of matter. Theoretically, these exotic states can be interpreted as either hadronic molecular states of genuine multiquark states, or even hybrid states containing gluons. In this talk, we will present a series of recent works on the production mechanisms of hidden charm pentaquarks with multiple strangeness $S=0,-1,-2,-3$, based on the fully off-mass-shell coupled channel formalism. The coupled-channel effects play an essential role in forming hadronic molecular states with charm mesons and single charmed baryons in $S$-wave. We also predict possible genuine pentaquark states with positive parity. We propose a plausible explanation of the reason for the null results of finding $P_{c\bar{c}}$'s from $J/\psi$ photoproduction by the GlueX experiment.

Speaker: Prof. Hyun-Chul Kim (Inha University)

HiddenCharmPentaquarks_HChKim_INPC2025.pptx

244 Probing physics beyond the TeV scale via nuclear beta decays

Precision measurements of observables that can be accurately predicted by the Standard Model (SM) can be used to search for physics beyond it. One of the most amazing features of the SM is the left-handedness of the charged part of the Weak Interaction. In the presence of new interactions beyond the SM, an interference effect takes place between these and the SM currents. Beta spectra measured with high precision (at the level of a part per thousand or better) allow sensitivities for new physics at the 1-TeV scale and beyond. I will describe the status of the He6-CRES experiment aiming at measuring spectra from 6He and 19Ne with high precision, using a new technique called cyclotron radiation emission spectroscopy (CRES). The technique is based on determining the beta energies from the cyclotron frequency, which can be measured from the microwave radiation that betas produce when the decays occur within a magnetic field.

Speaker: Prof. Alejandro Garcia (University of Washington)

garcia-korea.pdf

245 journal club: Fundamental Symmetries and Interactions in Nuclei

This journal-club-style coverage of published results of "Fundamental Symmetries and Interactions in Nuclei" since INPC2022 will leave out exciting experiments in progress. References will be in the slides. The speaker is showing his own work in a parallel session.
Parity:
The weak changed current in low- and medium-energy experiments has been mostly, but not entirely, explained by vector and axial vector Lorentz-transforming currents to precision part per thousand. E.g. LHC p+p -> e + missing Etransverse shows no events above background, which after EFT analysis excludes most Lorentz currents exchanging high-mass bosons.
A significant discrepany of the neutron beta-neutrino correlation experiment aSPECT can be explained by a Lorentz tensor interaction coupling to wrong-handed nu's, in tension with recent A=8 beta decay Paul trap results consistent with SM. Isospin-breaking 2nd-class currents can depend on nucleus, perhaps explaining such discrepancies, although lower-mass charged degrees of freedom are strongly constrained indirectly by observables like the running of alpha with energy.
New nuclear beta decay techniques seek to measure energy distortions of the beta spectrum from production of wrong-helicity beta's. Spectroscopy using cyclotron radiation (CRES) of the beta's has first results in PRL.
A PRL of no-core shell model with continuum calculations of nuclear virtual excitation better defines radiative corrections to Vud, where theory improvements suggest a significant SM discrepancy. Progress understanding the Nolen-Schiffer anomaly in isobaric mirror masses from strong interaction isospin breaking is producing possible additional tests of the isospin breaking in the critical wavefunction overlap calculation.
The weak neutral current is the main prediction of the SM. Deviations can be due to many things, including new particles coupling to nuclei. Observation by the COHERENT collaboration of stopped pion decay nu scattering from active detectors tests the weak neutral current strength. Interpreting atomic parity violation in cesium requires resolution of recent experimental discrepancies between two atomic physics methods. A relativity-produced M1 transition recently measured in francium atoms tests similar many-body calculations. The 2018 np -> d gamma 2 sigma unique evidence of weak neutral currents in nuclei lies outside the allowed timescale.
Time Reversal: (generally motivated by Sakharov's mechanism for matter-antimatter asymmetry, though the extra CP violation does not have to be observable now)
T odd, P odd TOPO:
J\=0 atomic EDM's (sensitive to electron EDM and semileptonic interactions involving nuclei) have reached similar null precision in HfF+ and ThO. Ambitious new neutron EDM searches have recent progress.
J=0 EDM 199Hg maintains the most precise null measurement, with Yb atomic trap methods becoming becoming competitive. Schiff moment and magnetic quadrupole moment experiments are publishing progress. Theory efforts to quantify the required nuclear matrix elements of difficult operators like sigma dot p are making progress. Recent creative phenomenology is clarifying sensitivity in abundant stable rare earth nuclei that do not have static octupole deformation-caused parity doublets but may have some degree of virtual octupole effects.
T odd, parity even TOPE: NOPTREX neutron scattering is progressing with sensitivity complementary to TOPO EDM's.
Pseudo-T violation in Decays: [Entangled K meson production allows true reversal of initial and final states PLB 2023, uniquely together with entangled B meson PRL 2012]. Final-state effects are likely under control for ambitious pseudo-time reversal beta decay test MORA. There is TOPE sensitivity in isospin-hindered beta decay.
The first new CP violation in 50 years in nu sector may have critical nucleus-dependent contributions, but along with double beta decay and sterile nu constraints from 7Be EC will hopefully be covered by others.

Speaker: John Behr (TRIUMF)

Presentation_ID498_Behr.pdf

246 QCD Link to the Light-Front Quark Model

I will present a mass gap solution of the 1+1D QCD in the large Nc limit known as the ‘tHooft model to discuss a link between QCD and the Light-Front Quark Model (LFQM). I will highlight the interpolation between the instant form dynamics and the light-front dynamics and discuss its utility in the computation of the parton distribution function (PDF). I will then illustrate the Bakamjian-Thomas construction of the LFQM exemplifying the recent resolution of the light-front zero-mode issue raised about a decade ago regarding the pion transverse momentum distributions (TMDs) beyond the leading twist.

Speaker: Chueng-Ryong Ji (North Carolina State University)

Presentation_ID716_Ji.pdf

13:00 Lunch

Excursion

Thursday, 29 May

Plenary Session: 6

Convener: Mathis Wiedeking (Lawrence Berkeley National Laboratory)

247 Probe element synthesis in star by deep underground nuclear astrophysics JUNA experiments

The Jinping Underground experiment for Nuclear Astrophysics (JUNA) is located in the ultra-low background environment of the China Jinping Underground Laboratory (CJPL). JUNA aims to study crucial stellar energy reactions in star evolution through direct experiments. In 2020, JUNA installed a high-current accelerator at the mA level based on an ECR source, along with high-efficiency BGO and 3He detectors. This setup allows JUNA to measure key nuclear reactions with 10-13 b sensitivity using beam exposures of a few hundred Coulombs. The Run 1 experiments include 25Mg(p,γ)26Al, 19F(p,αγ)16O, 19F(p,γ)20Ne, 13C(α,n)16O, 12C(α,γ)16O, and 18O(α,γ)20Ne, achieving improved precision and measurements closer to the Gamow window. These precise reaction rates offer valuable insights for high-precision astrophysics simulations. The highlights, upgrades, and Run 2 plans of JUNA experiments will be presented.

Speaker: Weiping Liu (Southern University of Science and Technology/China Institute of Atomic Energy)

248 Nuclear burning recorded in meteorites as a tracer of the birth of the Sun and its planets

In the past half century, thanks to ever-growing precision, laboratory analysis of meteorites has revealed clear fingerprints of the nuclear reactions that happen in stars. First major nuclear-burning signatures were found as pure stellar material, in the form of radioactive nuclei and micrometer-sized stardust. More recently, the variable imprint of nuclear processes in stars has also been found in whole meteorite rocks, albeit much diluted. While comparison of these data to nuclear-burning predictions is not trivial, it carries the unique power to investigate the birth of Sun, even if it happened 4.6 billion year ago. I will show how nuclear burning recorded in stardust provides insight of the ancient solar neighborhood, radioactive nuclei on the Sun's birth environment, and bulk meteorite isotopic variability on the evolution of the proto-planetary disk and planet formation.

Speaker: Maria Lugaro (Konkoly CSFK)

Presentation_ID528_Lugaro.pdf

Presentation_ID528_Lugaro.pptx

249 Better understanding of heavy element production via experimentally studying $^{56}$Ni(n,p) reaction rate and its impact on the $\nu$p process

Neutrino wind-driven supernova models provide strong evidence for the production of light, proton-rich heavy elements such as Sr, Y, and Zr, which remain inadequately explained by existing nucleosynthesis processes. This presentation will highlight on advancements in direct measurements of neutron-induced reactions on radionuclides, specifically the $^{56}$Ni(n,p) reaction, which plays a critical role in the $\nu$p-process nucleosynthesis pathway. Using the unique capabilities of Los Alamos Neutron Science Center’s neutron facility and its Isotope Production Facility (IPF), the reaction rate was experimentally measured for the first time. This study reveals the significant impact of neutron-induced reactions on proton-rich nuclei in better understanding of neutron poisoning reactions at waiting points, directly influencing elemental abundances. Advanced techniques in chemical separation, target fabrication, and collimation optimization were employed to produce and characterize high-purity samples, enabling precise cross-section measurements on radionuclides. These findings improve our understanding of the $\nu$p-process by including recent experimental rates to constrain astrophysical models and address uncertainties in astrophysical simulations. Future work includes developing an optimized solenoidal spectrometer and the upgraded neutron source at LANSCE to expand the scope of radionuclide reaction studies, improving nuclear astrophysics models and broadening the scientific impact of these experiments.

Speaker: Hye Young Lee (Los Alamos National Laboratory)

10:30 Break

Parallel Session: 5_Fundamental Symmetries and Interactions in Nuclei

Convener: Kyungwon Kim (Center for Underground Physics, IBS)

250 The Nab experiment: a probe of neutron decay

An intriguing anomaly has emerged in our understanding of the weak mixing of quarks, described by the Cabibbo Kobayashi Maskawa (CKM) matrix. Thanks to major strides in both theory and experiment, improved precision in determinations of the first row of matrix elements has revealed disagreement with the expectation of unitarity. The Nab experiment at the Spallation Neutron Source is designed to improve precision of the extraction of the first matrix element $V_{ud}$ and shed light on experimental tensions within the neutron beta decay dataset. Nab’s asymmetric spectrometer allows coincident reconstruction of the decay proton and electron energies, which are used to determine the electron-neutrino correlation coefficient, and thus (with the neutron lifetime) determine $V_{ud}$. This unique approach provides a more comprehensive view of neutron beta decay, including a first observation of the full phase space of the decay above 100 keV electron energy. This talk will present preliminary results from Nab’s first data collection runs and an outlook for its sensitivity in tests of CKM unitarity and to new physics beyond the Standard Model.

Speaker: Leah Broussard (Oak Ridge National Laboratory)

Presentation_ID466_Broussard.pptx

251 A new results of neutron lifetime measurement with cold neutron beam at J-PARC

The ``neutron lifetime puzzle'' arises from the discrepancy between neutron lifetime measurements obtained using the beam method, which measures decay products, and the bottle method, which measures the disappearance of neutrons.
To resolve this puzzle, we conducted an experiment using a pulsed cold neutron beam at J-PARC. In this experiment, the neutron lifetime is determined from the ratio of neutron decay counts to $^3$He(n,p)$^3$H reactions in a gas detector. This experiment belongs to the beam method but differs from previous experiments that measured protons, as it instead detects electrons, enabling measurements with distinct systematic uncertainties. By enlarging the beam transport system and reducing systematic uncertainties, we achieved a fivefold improvement in precision. Analysis of all acquired data yielded a neutron lifetime of $\tau_{\rm n}=877.2~\pm~1.7_{\rm(stat.)}~^{+4.0}_{-3.6}{}_{\rm (sys.)}$~s. This result is consistent with bottle method measurements but exhibits a $2.3\sigma$ tension with the average value obtained from the proton-detection-based beam method.

We will present about the new results.

Speaker: Prof. Kenji Mishima (Nagoya University)

Mishima_INCP2025_upload.pdf

252 Neutron Beta Decay Measurements with Polarized Neutrons and the Nab Spectrometer

The polarized neutron beam in conjunction with the Nab spectrometer (pNAB) at the Fundamental Neutron Beam Line (FnPB) at the Spallation Neutron Source (SNS) enables groundbreaking simultaneous measurements of the beta (A) and neutrino (B) asymmetries in free neutron decay. These measurements will complement ongoing Nab experiments utilizing an unpolarized neutron beam and the Nab spectrometer to determine the electron-antineutrino correlation coefficient (a) and the Fierz interference term (b) with high precision. The combined results from the Nab and pNAB measurements of the parameters a, A, and B will facilitate the determination of the ratio of axial-vector to vector coupling constants (λ=g_A⁄g_V ) in the weak interaction with unprecedented precision, achieving an accuracy on the order of 0.01%. This represents an order-of-magnitude improvement over current experimental limit. Additionally, by integrating these results with precise experimental measurements of the neutron lifetime, the most stringent test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix using free neutron decay will be realized. Furthermore, the determination of the Fierz interference term b will probe physics beyond the Standard Model, providing a unique opportunity to test potential deviations from established theory. This presentation will focus on the pNAB scientific program, detailing the performance capabilities of the Nab spectrometer and outlining strategies for achieving a highly polarized and precisely characterized neutron beam.

Speaker: Ricardo Alarcon (Arizona State University)

Presentation_ID330_Alarcon.pptx

253 Advancing Beyond Standard Model Physics with Cryogenic Detectors: The ASGARD Experiment and Novel Applications

The advent of novel cryogenic detectors has significantly broadened the scope of Beyond Standard Model searches at low energy, with promises of shedding light on, e.g., the neutrino mass scale and even fundamental aspects of quantum mechanics. Superconducting tunnel junction detectors, for example, have recently been used to pioneer direct spectroscopy of recoiling nuclei following electron capture decays with eV-scale resolution, which proved competitive in sterile neutrino searches [1] and the determination of the size of the neutrino wave packet [2]. Even so, several technical and conceptual hurdles remain which limit their broad, competitive deployment for fundamental symmetries and nuclear structure searches. In this talk, we will outline the ASGARD experiment, which aims to perform Beyond Standard Model physics searches at the (tens of) TeV scale directly at radioactive ion beam facilities [3]. In addition, we will highlight novel applications in nuclear structure studies and exotic decay modes.

[1]: Friedrich et al. (BeEST collaboration), Physical Review Letters 126 (2021) 021803

[2]: Smolsky et al. (BeEST collaboration), arXiv:2404.03102, Accepted at Nature

[3]: Hayen, Annual Reviews of Nuclear and Particle Science 74 (2024) 497

Speaker: Leendert Hayen (LPC Caen)

Presentation_ID701_Hayen.pptx

Parallel Session: 5_Hot and Dense Nuclear Matter

Convener: Vadim Kolesnikov (JINR)

254 Speed of sound exceeding the conformal bound in dense QCD-like theories

We investigate the phase structure and the equation of state (EoS) for dense two-color QCD at low temperatures using the lattice Monte Carlo simulations. A rich phase structure below the pseudo-critical temperature $T_c$ as a function of quark chemical potential $\mu$ has been revealed. In high density regime, we can see a superfluid phase, where the diquark condensate takes non-zero expectation value. We newly found that the speed of sound exceeds the conformal bound, $c_{\mathrm s}^2/c^2 = 1/3$, which is the value of relativistic free theory.

Speaker: Etsuko Itou (YITP, Kyoto U.)

Presentation_ID300_Itou.pdf

255 The chiral magnetic effect in relativistic heavy ion collisions—an experimental perspective

The chiral magnetic effect (CME) refers to a charge separation along an external magnetic field arising from an imbalance of quark chirality in quantum chromodynamics. The CME has been searched for in relativistic heavy ion collisions where such a chirality imbalance has been predicted and a strong magnetic field is created. No firm conclusion has been reached so far because of a large background contribution to mimic a charge separation signal. Many novel observables and techniques have been invented, some of which are more promising than others. In this talk, I will discuss some of these observables and techniques, with pros and cons, and present a perspective on the experimental search for the CME.

Speaker: Fuqiang Wang (Purdue University)

Presentation_ID671_Wang.pdf

256 Recent Highlights from the PHENIX Experiment

Quark-gluon plasma (QGP) is a state of matter in which quarks and gluons are deconfined from hadrons. Studying this extreme state has been a major focus of high-energy nuclear physics for several decades. The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) in the United States has played a central role in advancing our understanding of this phase. In particular, the PHENIX (Pioneering High Energy Nuclear Interaction Experiment) experiment at RHIC has accumulated extensive data across nine collision species and nine collision energies, providing critical experimental insights into the properties of QGP under conditions of temperature and energy density similar to those found in the early universe.

Since its first operation in 2000, PHENIX has produced numerous significant results. For example, the discovery of strong elliptic flow ($v_\textrm{2}$) in non-central collisions provided important evidence for the collective behavior of QGP, suggesting that it behaves as a nearly perfect fluid with extremely low viscosity. Additionally, the observation of high transverse momentum yield suppression, commonly known as jet quenching, revealed that QGP strongly interacts with high-$p_{\rm{T}}$ partons produced in the initial stages of the collision, leading to substantial energy loss.

Although data collection was completed in 2016, the PHENIX collaboration remains highly active, continuing to extract new results from its rich dataset, including updated measurements of direct photon $v_2$ and heavy flavor production with charm and bottom quark separation.

In this presentation, we will highlight recent PHENIX results and discuss the new insights they provide into the nature of the quark-gluon plasma.

Speaker: maya shimomura (Nara Women's University)

Presentation_ID694 _shimomura_fixed.pdf

Presentation_ID694 _shimomura_fixed.pptx

257 Onset of hydrodynamics in a strongly coupled system based on quantum many-body calculation

Onset of hydrodynamics in the hot medium created in relativistic heavy-ion collisions is a crucial theoretical question. A first principle calculation requires a real-time, non-perturbative simulation of the quantum system. In the current study, we perform such a simulation using the Tensor Network method, which enables simulations of large scale quantum many-body systems by keeping only the most essential quantum states in the Hilbert space. We focus on the massive Schwinger model which is a low-dimension analog of quantum chromodynamics (QCD), as it shares the important properties such as confinement and chiral symmetry breaking.

Starting from an initial quantum state that mimics hard particle collisions, we observe the onset of hydrodynamic behavior that is consistent with the Bjorken-flow in all hydrodynamic degrees of freedom: energy density, fluid velocity, and bulk pressure. The time scale for the onset of hydrodynamics is found to be consistent with the thermalization time of the quantum distribution function. Both time scales are of the same order as the hydrodynamization time determined by fitting the experimental data, upon a physical matching that extrapolates the 1+1 dimensional Schwinger model to the 3+1 dimension QCD.

Speaker: Shuzhe Shi (Tsinghua University)

QuantumHydrodynamization_ShuzheShi.pdf

258 Probing fluctuating color fields of QCD matter from spin alignment in relativistic heavy ion collisions

In high-energy nuclear collisions, a considerable number of gluons can be produced in the quark gluon plasma or even the glasma phase as its precursor with overpopulated gluons that may be delineated by fluctuating chromo-electromagnetic fields (or color fields for short) in the color-glass-condensate effective theory. The recent measured spin alignment signals of vector mesons in relativistic heavy-ion collisions, possibly stemming from fluctuating spin correlations of quarks and antiquarks in the quark coalescence scenario for the formation of vector mesons, could provide an alternative probe for such fluctuating color fields. By utilizing the recent developed quantum kinetic theory of quarks with phenomenological models and approximations, we investigate the momentum dependence for dynamical spin alignment of $\phi$ mesons from color fields in the glasma phase. Also, the non-dynamical spin alignment coming from the color fields characterizing soft thermal gluons in the quark gluon plasma is qualitatively studied for comparison. Moreover, we propose to employ both the transverse and longitudinal spin alignment perpendicular and parallel to the beam direction, repectively, to further distinguish the different underlying effects.

References :
[1] B. Mueller and D.-L. Yang, Anomalous spin polarization from turbulent color fields,
Phys. Rev. D 105 (2022) L011901 [2110.15630].
[2] A. Kumar, B. Mueller and D.-L. Yang, Spin alignment of vector mesons by glasma fields, Phys. Rev. D 108 (2023) 016020 [2304.04181].
[3] D.-L. Yang, Transverse and longitudinal spin alignment from color fields in heavy ion collisions, [2411.14822].

Speaker: Di-Lun Yang (Academia Sinica)

INPC2025_DLYang.pdf

259 Probing momentum-dependent hydrodynamization in nuclear collisions

The relativistic hydrodynamic model has been vital to the analysis of the QCD matter created in high-energy heavy-ion collisions. Experimental data indicate that low momentum particles are thermal and hydrodynamic, while high momentum particles are non-thermal and perturbative. In this study, we investigate two scenarios - (i) the 'violet' hydrodynamic model where an extended momentum range is treated as hydrodynamic based on nonextensive statistics, and (ii) the 'red' hydrodynamic model where high momentum contributions are excluded from the bulk medium - to elucidate the momentum dependence of thermalization/hydrodynamization and its effect on flow observables in heavy-ion collisions using numerical simulations.

Speaker: Akihiko Monnai (Osaka Institute of Technology)

Presentation_ID437_Monnai.pdf

Parallel Session: 5_Neutrinos and Nuclei

Convener: Dong Ho Moon (Chonnam National University)

260 AMoRE-II: Searches for neutrinoless double beta decay from 90 kg of Mo-100 using cryogenic calorimeters

In recent decades, the neutrino physics has been a frontier field, advancing our understanding of nuclear and particle physics. Despite numerous experimental observations, some fundamental questions about neutrinos remain unanswered, such as their nature as Dirac or Majorana particles and their absolute mass scale. The search for neutrinoless double beta decay is a powerful tool to address these questions and has been ambitiously pursued worldwide. The AMoRE collaboration is conducting the AMoRE-II experiment, which will utilize approximately 90 kg of Mo-100, a promising candidate nucleus for this decay, embedded in an array of cryogenic calorimeters. This experiment builds upon the success of its predecessors, AMoRE-pilot and AMoRE-I, which set the most sensitive limit on the half-life of neutrinoless double beta decay from Mo-100. With the new underground experimental site in Yemilab, situated beneath a 1000-m-thick rock overburden, and rigorous efforts to achieve the background level of 10^-4 counts/keV/kg/year in the signal region of interest, AMoRE-II aims to reach the sensitivity of 4.5 x 10^26 years for the half-life of the decay from Mo-100. The current status and prospects of the experiment will be discussed in this presentation.

Speaker: SeungCheon Kim (CUP, IBS)

presentation_ID389_Kim.pdf

261 Neutrino-nucleus interactions for oscillation experiments

Neutrino interactions with nuclei have recently attracted significant attention due to various experimental efforts aimed at probing new physics. Notably, long-baseline neutrino oscillation experiments, such as Hyper-Kamiokande (Japan) and DUNE (USA), will soon enter the Precision Era. To maximize their impact, these experimental advancements must be complemented by accurate theoretical calculations to reduce systematic uncertainties and enhance the experimental sensitivity to fundamental constants.
In this talk, I will discuss the opportunities and challenges that nuclear theory faces in the context of neutrino oscillation experiments. Particular emphasis will be placed on ab initio methods and the significant progress made over the last few years, with a focus on results relevant to long-baseline experiments.

Speaker: Joanna Sobczyk

INPC2025_jsobczyk.pdf

262 Influence of the Majoron on Primordial Nucleosynthesis

The Majoron is a hypothetical Goldstone boson arising from the spontaneous breaking of lepton number symmetry. Due to its presumed long-lived nature, the Majoron has the potential to influence Big Bang Nucleosynthesis (BBN). Our study investigates how non-thermal energetic neutrinos, produced through Majoron decays, can drive various neutrino-induced nuclear reactions. Notably, these reactions may generate additional neutrons via inverse beta decay. This mechanism could enhance key processes such as 7Be(n,p)7Li and 7Li(𝑝,𝛼)4He, potentially addressing the long-standing discrepancy between the observed and theoretically predicted 7Li abundance. Furthermore, we explore how BBN constraints can impose limits on the parameter space of the Majoron.

Speaker: Tae-Sun Park (CENS, IBS)

Presentation-ID601-Park.pptx

263 Neutrino-nucleus reactions on argon and oxygen

Neutrino-induced reactions on nuclear targets, which are important for neutrino detection and neutrino properties, are studied.
The B(GT) and charged-current reactions on $^{40}$Ar were studied based on the monopole-based universal interaction [1] within the $sd^{-2}pf^{2}$ shell-model space [2]. Here, a new effective interaction in the $sd$-$pf$ shell obtained by the extended Kuo-Krenciglowa (EKK) method [3] is used in the study of both charged- and neutral-current reactions on $^{40}$Ar. The B(GT), B(M1), and the reaction cross sections are evaluated by the shell model for the 1+ multipole in the $sd^{-2}pf^{2}$ +$sd^{-4}pf^{4}$ model space, while forbidden transitions are treated by RPA [4]. Calculated results are compared with the previous study [2], and the dependence of the cross sections on the quenching of the axial-vector coupling constant $g_A$, constrained by the experimental B(GT) and B(M1) data, is examined [4].
The effective interaction in the $sd$-$pf$ shell obtained by the EKK method is used to study the GT $\beta$-de cay strength of $sd$-shell nuclei with contributions including up to 2p-2h excitations. The extension of the model space is found to enhance the quenching factor for $g_A$ by $\sim$0.05 compared to the conventional Hamiltonians in the sd-shell [5].\

Neutrino-nucleus reaction cross sections on $^{18}$O are evaluated by shell-model calculations and compared with those on $^{16}$O [6]. The cross sections for $^{18}$O ($\nu_e$, e$^{-}$) $^{18}$F are larger than for $^{16}$O at low neutrino energies below 20 MeV in natural water with the 0.205$\%$ admixture of $^{18}$O due to the lower threshold energy for $^{18}$O than that for $^{16}$O and large contributions from the GT transitions in $^{18}$O. Events from reactions on $^{16}$O and $^{18}$O, which take place at different electron energies separated by 10-15 MeV, are shown to be distinguished by the measurements of DAR $\nu_e$ [5]. Possible effects of the $^{18}$O admixture in water Cherenkov detectors on the evaluations of the event rate of supernova neutrinos are examined for both the cases with and without the neutrino oscillations [7].

[1] T. Otsuka, T. Suzuki, M. Honma, Y. Utsuno, N. Tsunoda, K. Tsukiyama, and M. Hjorth-Jensen, Phys. Rev. Lett. 104, 012501 (2010)
[2] T. Suzuki and M. Honma, Phys. Rev. C 87, 014607 (2013).
[3] N. Tsunoda, T. Otsuka, N. Shimizu, M. Hjorth-Jensen, K. Takayanagi and T. Suzuki, Phys. Rev. C 95, 021304 (2020); N. Tsunoda, T. Otsuka, K. Takayanagi, N. Shimizu, T. Suzuki, Y. Utsuno, S. Yoshida, H. Ueno, Nature 587, 66 (2020).
[4] T. Suzuki and N. Shimizu, Phys. Rev. C 108, 014611 (2023).
[5] T. Suzuki and N. Shimizu, Frontiers in Physics 12, 1434598 (2024).
[6] T. Suzuki, S. Chiba, T. Yoshida, K. Takahashi and H. Umeda, Phys. Rev. C 98, 034613 (2018).
[7] T. Suzuki, k. Nakazato and M. Sakuda, Nucl. Phys. A1038, 122719 (2023).

Speaker: Prof. Toshio Suzuki (Nihon University)

Presentation_ID6_Suzuki.pdf

Parallel Session: 5_New Facilities and Instrumentation

Convener: In Kwon Yoo (Pusan National University)

264 Highlights from INFN-LNL, the Status and the Future plans of the SPES project

INFN-LNL is a large scale facility that offers for users access to up to 5 accelerators covering a large range of ions ( from proton to Uranium) and a large range of energy (few hundreds of KeV to few Tens of MeV per nucleon). The flagship project of LNL is SPES (Selective Production of Exotic Species) that aims at the realization of an accelerator facility for research in the fields of Fundamental Physics and Interdisciplinary Physics usings ISOL (Isotope Separation On Line) type of rare isotopes. SPES aims also at building a facility that will be dedicated to Research and Development of innovative radioisotopes for medical diagnostics and therapies.
The status and future plans of the SPES project as well as some highlights from LNL related to the AGATA measurements campaign will be presented.

Speaker: Prof. Faical Azaiez (LNL-INFN)

Presenmtation_ID218_azaiez.pptx

265 Recent Progress of KoBRA Beam Commissioning at RAON

Korea Broad acceptance Recoil spectrometer and Apparatus (KoBRA) was constructed at the Institute for Rare Isotope Science (IRIS), as a part of the Rare isotope Accelerator complex for ON-line experiments facility (RAON) in Korea [1−3]. Stable isotope (SI) or radioactive isotope (RI) beams can be produced using Electron Cyclotron Resonance (ECR) ion sources or the Isotope Separation On-Line (ISOL) system at RAON, respectively, and these beams can be delivered to KoBRA at energies of 1 − 40 MeV/u via the SuperConducting Linear accelerator 3 (SCL3). KoBRA will serve as a multi-purpose experimental instrument to cover various studies of low-energy nuclear physics−encompassing nuclear reaction, astrophysics, and nuclear structure−by capitalizing on its large momentum and angular acceptances (∆p/p = 8% and Ω = 13.9 msr) together with the RAON facility’s capabilities of providing various SI and RI beams over a wide low-energy range.
KoBRA has been in the beam commissioning phase since May 2023, following its off-line beam commissioning using an $^{241}$Am α-particle source. In this early commissioning phase, 16-MeV/u $^{40}$Ar primary beam was successfully transported, and secondary RI beams produced from the reaction $^{40}$Ar + $^{12}$C were investigated. Particle identification was performed using standard methods based on energy loss (∆E), time-of-flight (ToF), and magnetic rigidity (Bρ). Furthermore, 16-MeV/u $^{25}$Na radioactive isotope beam produced from the ISOL system was transported to KoBRA, and its beam energy, particle identification, and purification were examined. In this presentation, we will report on the recent progress of KoBRA beam commissioning, along with the preliminary experimental results.

References
[1] K. Tshoo et al., Nucl. Instrum. Methods Phys. Res. B 317 (2013) 242−247.
[2] K. Tshoo et al., Nucl. Instrum. Methods Phys. Res. B 376 (2016) 188−193.
[3] K. Tshoo et al., Nucl. Instrum. Methods Phys. Res. B 541 (2023) 56−60.

This work was supported by the Institute for Basic Science (IBS-I001-01) and the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2013M7A1A1075764, RS-2022-00165168, RS-2023-00282876), Republic of Korea.

Speaker: Dong Geon Kim (Hanyang University)

Presentation_ID414_KIM_final.pptx

266 SIRIUS (Spectroscopy and Identification of Rare Isotopes Using S3 ) at GANIL

The stability of nuclei beyond the spherical double shell closure of $^{208}$Pb decreases because of the disappearance of the macroscopic fission barrier. This phenomenon is however compensated by quantum shell effects caused by alternating zones of high and low level densities induced by deformation. The island of superheavy stability is predicted as a doubly spherical gap whose position varies depending on the model used. Spectroscopy in the region of high masses is very close to the sensitivity limits of the existing detection systems. The extension of the investigation on nuclear structure to heavier nuclei is governed by an improvement in the efficiency of the transport and selection of the nuclei of interest as well as in the detection systems. The very high intensity beams provided by the LINAC, combined with the projected high transmission and selection power of the Super Separator Spectrometer (S$^3$), will offer unprecedented production rates of nuclei in the nanobarns region.

SIRIUS (Spectroscopy and Identification of Rare Isotopes Using S$^3$) will be the detection system dedicated to spectroscopy experiments for superheavy nuclei with S$^3$. SIRIUS consists of five segmented silicon detectors optimized for precision spectroscopy of alpha, beta and fission decay, surrounded by five EXOGAM high-purity germanium detectors for gamma-rays, and a Secondary Emission Detector (SED) placed upstream to track the ions and measure their time of flight. The conjunction of these detectors with the mass resolving power and the transmission of S$^3$ will make it a unique instrument for the study of superheavy nuclei.

In this contribution, after a brief review of the current status of S$^3$, we will report on the offline tests of SIRIUS and the performances of its detectors.

Speaker: Armand Bahini (GANIL)

Presentation_ID238_Bahini.pdf

267 Commissioning and operation of LEAF with high intensity heavy ion beams

LEAF (Low Energy Heavy Ion Accelerator Facility) is a high-intensity, low-energy heavy-ion accelerator complex that features a high-performance superconducting ECR (Electron Cyclotron Resonance) ion source and a high-current, room-temperature linear accelerator. The facility delivers heavy-ion beams ranging from H2+ to uranium, with tunable beam energies between 0.3 and 1 MeV/u. Since its trial operation began in 2018, the facility has achieved remarkable beam intensities in continuous-wave (CW) mode, including: >160 pµA for the 16O ion beam, >6 pµA for the 209Bi ion beam, and >45 pµA for the 40Ar ion beam. These beam intensities are among the highest achieved by similar facilities worldwide. Recently, LEAF successfully delivered carbon ion beams with an intensity exceeding 100 pµA and an energy spread of <0.3% (FWHM) for C-C burning investigations in nuclear astrophysics. Significant results have been obtained. This paper provides an introduction to the LEAF facility.

Speaker: Yao Yang (Institute of Modern Physics, Chinese Academy of Sciences)

INPC2025_Yao YANG-0527-New.pptx

268 Nuclear Photonics at ELI-NP

Extreme Light Infrastructure - Nuclear Physics (ELI-NP) represents a novel research infrastructure that has been implemented in Romania as part of the pan-European Extreme Light Infrastructure project. The primary focus of ELI-NP is research in the field of nuclear photonics which involves the use of extreme electromagnetic fields for nuclear physics studies and related topics. To this end, two state-of-the-art sources of extreme light are being implemented at ELI-NP: a high-power laser system and an intense gamma beam system. These systems facilitate research in a broad range of topics, with the objective of pushing scientific and technological knowledge beyond its current boundaries.

Presently, ELI-NP is the host of the most powerful laser system in operation worldwide of 2 x 10 PW power. The fundamental physics research conducted presently at ELI-NP with high-power lasers is focused on two main objectives: the understanding of the nature of the laser–matter interaction and the development of novel particle acceleration schemes that are complementary to the present classical accelerators. The extreme electrical fields produced by the high-power lasers, reaching peak values of the order of 10$^{15}$ V/m, and the very high pressure to which matter is compressed, of the order of Tbars, have been shown to accelerate electrons to energies of 10’s of GeV on cm’s scale. This development opens new opportunities for QED studies, e.g. study of Breit-Wheeler pair production process. Furthermore, protons and ions can be accelerated to 100’s of MeV/amu on microns scale with extremely high beam densities.
The prospect of studying nuclear reactions in plasmas that replicate the conditions of stellar environment is being made possible by the use of high-power lasers. This approach enables the determination of cross sections for astrophysically relevant reactions or the investigation of nuclear states lifetimes as a function of the plasma temperature. Production of laser-driven brilliant neutron beams have the potential to provide new opportunities for the study of neutron physics and applications.

The applications of laser-based secondary beams are naturally emerging from the basic research conducted at ELI-NP. Two main application fields with significant societal benefits are in particular being pursued at ELI-NP: medical applications and energy. The medical applications of high-power lasers are focused on: hadron-therapy with C ion, high-accuracy low-dose X-ray interferometric imaging, and production of radioisotopes, in an integrated approach where the same lasers can be used for more applications in a hospital environment at a later stage. Fusion ignition with short pulsed high-power lasers is a subject of interest at ELI-NP. Other potential applications include the study of material aging and cell behavior in extraterrestrial mixed radiation fields.

The ELI-NP is evolving into a multipurpose unique research center where nuclear physics research and related applications introduce novel approaches, such as laser-driven particle acceleration, that complement classical accelerators. This overview is intended to provide a comprehensive introduction to this state-of-the-art facility which is user facility since 2022. It will also discuss the facility's recent achievements and how they align with the original scientific case.

Speaker: Dr Calin Alexandru Ur (ELI-NP / IFIN-HH)

Presentation_ID316_Ur.pdf

Parallel Session: 5_Nuclear Astrophysics (1)

Convener: Grant Mathews (University of Notre Dame)

269 Nuclear Collective Vibrations: from Lab to Stars

Nuclear physics study is essential in understanding the nuclear equation of state (EoS), the origin of heavy elements in the universe, as well as the properties of neutrinos. Nuclear collective vibrations, an important mode of nuclear excitations, play important roles in these studies.
In this talk, I will introduce a state-of-art quasiparticle vibration coupling (QPVC) model to study nuclear collective vibrations. Based on this model, the unified description of giant monopole resonances in Sn and Pb isotopes is achieved, which solves the nuclear physics puzzle of “Why are the EoS for tin so soft” lasted for almost 20 years; the description accuracy of beta-decay half-lives is increased by about an order of magnitude, which provides reliable nuclear physics inputs for nucleosynthesis study.
Therefore, this model provides a promising tool for the further study of neutrinoless double beta decay and photo-nuclear reaction. The role of different interaction channels in describing the 0nbb nuclear matrix elements has been clarified, and QPVC model is expected to further reduce the discrepancies of NME calculations among different nuclear models. Vortex photon is proposed as an effective probe to excite giant multipole resonances, which opens a novel avenue in photo-nuclear physics.

Speaker: Yifei Niu

Presentation_ID400_Niu.pdf

Presentation_ID400_Niu.pptx

270 Constraining of Nuclear Matter Equation of States with Rotating Neutron Stars

In terrestrial experiments one may extract information about the nuclear equation of state (EoS) near saturation density. Developments of astronomical observation technology have enabled the study of the EoS at higher densities, which are difficult to replicate experimentally, through information derived from astronomical phenomena of neutron star. These observational findings not only allow for the validation of parameter sets in existing nuclear models within high-density regimes but also provide valuable data for refining parameters during the model-fitting process.

An example of parameter fitting is incorporating neutron star mass-radius curves. However, most EoS studies involving neutron stars utilize the Tolman-Oppenheimer-Volkoff (TOV) equation, which assumes a spherically-symmetric hydrostatic equilibrium state. Needless to say, neutron stars rotate, and this rotation can deform their equilibrium shape, potentially altering the mass-radius relationship. Among the numerical methods developed to model rotating celestial objects, the Komatsu-Eriguchi-Hachisu (KEH) method, proposed in 1989 [1], is considered the most stable and reliable.

In this study, we have newly developed a computational code of the KEH method and applied it to describe rapidly rotating neutron stars with nuclear EOSs based on Skyrme and Gogny interactions. We have found that M-R relation changes substantially when angular frequency exceeds about 500 Hz. Namely, for a given central density, both mass and radius are increased by the rotational effect. Specifically, the shape of a neutron star with 1.4 solar mass is deformed in oblate shape with a ratio of longer and shorter axes roughly 0.93 to 0.83 for angular frequency 600 Hz to 800 Hz in case of SLy230a EoS. It underlines the importance of considering rotational effects on the M-R relations in assessing EoS against observational data. In this talk, we will discuss possible implications of our findings for astrophysical modeling of neutron stars.

[1] H. Komagtsu, Y. Eriguchi, I. Hachisu, Mothly Notice. Sup. 237, 355-379(1989)

Speaker: Hyukjin KWON (Institute of Science Tokyo)

Presentation_ID095_Hyukjin.pptx

271 Early-stage deveploments about studying Ta-180m decay at cryogenic temperature

Ta-180m is the longest-lived metastable nuclear isomer, with no observed decay. Investing this decay could provide valuable insights into the nucleosynthesis mechanisms, K-spin violation, and the dark matter. This study will utilize a cryogenic calorimeter equipped with a metallic magnetic calorimeter (MMC), leveraging its high detection efficiency to investigate the decay channels of Ta-180m, including the internal conversion, a channel with highest branching ratio. As an initial step, we plan to conduct measurements using a 20 g tantalum single crystal as a target absorber.

In the presentation, we will discuss about our experimental proposal, along with potential low background measurement at Yemi Underground Laboratory (Yemilab), the candidates of different absorber forms, and the enrichment of Ta-180.

Speaker: Woo Tae Kim (IBS-CUP)

Presentation_ID552_Kim.pdf

272 Hadrons vs quarks: A Bayesian model comparison through neutron star observables in light of nuclear and astrophysics data

The equation of state of matter (EOS) inside neutron stars (NSs) is far from being exactly known. An extremely dense neutron star core is believed to contain exotic matter such as hyperons, quark-gluon plasma and so on, in addition to nucleons. Results from terrestrial nuclear physics experiments and astrophysical observations are routinely incorporated during EOS modelling to simulate cold NSs. As far as astrophysical observations are concerned, mass-radius inferences with gravitational wave (GW) data from binary NS mergers and X-ray observation data of pulsars have provided excellent constraints on the EOS of cold NS matter in the recent past.

We examine whether recent observational data from NICER and LIGO-Virgo (LV) collaborations in combination with nuclear physics constraints favour NS EOSs with hadron-quark phase transitions (PTs) over purely hadronic EOSs through Bayesian inference.

Our set of NS matter EOSs with hadron-quark PTs (hybrid EOS model) combines two models - a relativistic mean-field (RMF) model for nucleonic regime and a mean-field theory of quantum chromodynamics (MFTQCD) for quark regime.

Observational data for pulsars PSR J0030+0451 and PSR J0470+6620 show a slight preference for EOSs with smooth phase transitions, unlike gravitational wave (GW) data, which remain practically indecisive.

Our analysis also highlights tensions between older NICER data and recent measurements for PSR J0437$-$4715. We observe a clear distinction between the 90% credible interval for NS observables like mass, radius, tidal deformability, f-mode oscillation frequency and GW damping time for hadronic and hybrid EOSs. The hybrid model allows stiffer EOSs that align with NICER data but result in higher tidal deformabilities, at odds with GW observations. Our results indicate the need for more flexible EOS models to resolve the disagreement between astrophysical observations.

Speaker: Mr Debanjan Guha Roy (Department of Physics, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Secunderabad, Telangana 500078, India)

Parallel Session: 5_Nuclear Astrophysics (2)

Convener: Weiping Liu (Southern University of Science and Technology/China Institute of Atomic Energy)

273 Direct Measurements of Key Reactions in Nuclear Astrophysics

Astrophysical observables, such as the luminosity of X-ray bursts, are influenced by nuclear reaction chains occurring within stars. The nuclear properties of both stable and radioactive isotopes involved in nucleosynthesis, including nuclear masses and reaction rates, play a critical role in shaping stellar evolution. However, significant uncertainties in theoretical models and a lack of experimental data for proton-, neutron-, and alpha-induced reactions with stable or radioactive beams limit the accuracy of our understanding of these phenomena. To address these challenges, the nuclear astrophysics group at CENS conducts direct measurements of key reaction cross-sections. This presentation will highlight current efforts at CENS to study nuclear properties relevant to nucleosynthesis and outline future research plans.

Speaker: Dr Sunghoon(Tony) Ahn (Center for Exotic Nuclear Studies, Institute for Basic Science)

INPC2025_TonyAhn_final.pdf

INPC2025_TonyAhn_final.pptx

274 Preliminary study of the 19F(p,γ)20Ne at LUNA

The $^{19}$F(p,γ)$^{20}$Ne reaction plays a pivotal role in nucleosynthesis, particularly in the breakout from the CNO cycle to heavier elements. Its contribution is critical to understanding the elemental evolution of first-generation stars and the production of observed calcium abundances in metal-poor stars, but it is still not well constrained as demonstrated in the recent studies.
The LUNA (Laboratory for Underground Nuclear Astrophysics) facility, located deep underground to minimize cosmic-ray-induced background, is uniquely suited for precise low-energy nuclear astrophysics studies, as demonstrated in the past. As part of a dedicated effort to study the $^{19}$F(p,γ)$^{20}$Ne reaction, initial irradiations were recently performed to evaluate and characterize three different types of targets. Each target type demonstrated distinct and complementary properties, allowing us to refine our approach for subsequent measurements.
Preliminary results that will be presented include target stability assessments and early observations of the two resonances of astrophysical interest. These findings lay the groundwork for further precise investigations into this reaction, more importantly in the region where the direct capture dominates, and give a first comparison with the novel findings of the JUNA collaboration.

Speaker: Jakub Skowronski (Università degli Studi di Padova)

Presentation_ID569_Skowronski.pdf

275 Accelerating sensitivity studies for Type I X-ray burst with deep learning

Type I X-ray bursts (XRBs) are explosive astrophysical phenomena powered by hundreds of thermonuclear reactions in the rapid proton capture process (rp-process). Sensitivity studies with XRB simulation codes have been used to identify nuclear reactions that have the most impact on observables and should be prioritized for future studies. Due to the high computational cost and time-consuming nature of hydrodynamic simulations, previous sensitivity studies only considered the impact of variations of one reaction rate at a time. Consequently, the impacts of reaction correlations by simultaneous variation of multiple rates have not been well investigated.
We propose a novel deep learning approach to emulate XRB simulations and significantly accelerate predictions of XRB observables. By training a deep neural network on datasets of XRB properties generated with the multi-zone hydrodynamic code MESA, we can explore the impact of simultaneous variations of multiple reaction rates. This enables us to identify unexplored combinations of reactions that have substantial influence on XRB properties. Details of the method and preliminary results will be presented.

Speaker: Sohyun Kim (Sungkyunkwan University)

Presentation_ID120_Kim.pdf

276 Direct Cross-Section Measurement of the 14O(α,p)17F Reaction Critical for the Type-I X-ray Burst Light Curve

This study presents the first direct measurement of the $^{14}\mathrm{O}(α,p)^{17}\mathrm{F}$ cross section using an active target time projection chamber. The reaction is one of the key reactions influencing the light curve of Type I X-ray burst models [1]. Additionally, this reaction rate plays an important role in the break-out from the hot CNO cycle to the rp-process at high temperatures (T$_9$ > 0.5) [2]. However, due to the lack of experimental data, its precise contribution to astrophysical observables has remained uncertain.
To address this challenge, a direct measurement of the $^{14}\mathrm{O}(α,p)^{17}\mathrm{F}$ cross section was performed. A $^{14}$O beam was produced at the CNS Radioactive Ion Beam separator (CRIB) at RIKEN [3], using an 8.40 MeV/u $^{14}$N beam and a H$_2$ cryogenic gas-cell target. The experiment utilized the Texas Active Target Time Projection Chamber (TexAT), which was originally developed at Texas A&M University [4]. The device was upgraded to TexAT_v2 by the Institute for Basic Science (IBS) to allow high beam intensity and low-energy proton detection capability [4, 5]. The three-dimensional tracking capability of TexAT_v2 improves the energy and position resolution of detected particles, enhancing cross-section measurements. The excitation function of the $^{18}$Ne compound nucleus was successfully measured down to about 0.5 MeV in center-of-mass energy.
The experimental setup, as well as analysis results, will be presented and discussed.

References
[1] R. H. Cyburt et al., Astrophys. J. 830, 55 (2016).
[2] R. K. Wallace and S. E. Woosley, Astro. J. Suppl. Ser. 45, 389 (1981).
[3] S. Kubono et al., Eur. Phys. J. A 13, 217 (2002)
[4] E. Koshchiy et al., Nucl. Inst. and Meth. A 957, 163398 (2020).
[5] C. Park et al., Nucl. Inst. and Meth. B 541 (2023)

Speaker: Chaeyeon Park (Ewha Womans University / CENS(IBS))

Presentation_ID358_Park.pdf

Parallel Session: 5_Nuclear Reactions (1)

Convener: Nori Aoi (CNS, Univ. of Tokyo)

277 Soft dipole resonances in light neutron-rich and proton-rich nuclei

We investigate the possibility of the soft dipole resonances in light unstable nuclei, in particular, neutron-rich $^8$He and proton-rich $^8$C nuclei. This exotic resonance is considered to be a collective oscillation of four valence neutrons/protons against the $\alpha$ core. We also discuss the isospin symmetry in these mirror nuclei. We use the five-body cluster model and many-body resonances are described with the complex scaling.
We obtain the $1^-$ resonances in two nuclei with the similar excitation energies of around 13 MeV showing broad decay width and their structures are similar to each other such as the spatial properties. These results indicate a good isospin symmetry in the soft dipole resonances with collective excitations of multineutrons and multiprotons, while the ground states of two nuclei show different properties due to the Coulomb repulsion in $^8$C, leading to the symmetry breaking. In conclusion, the isospin symmetry is depending on the states of $^8$He and $^8$C.

Speaker: Prof. Takayuki Myo (Osaka Institute of Technology)

Presentation_ID675_Myo.pdf

278 Population of tetraneutron continuum in reactions of 8He on deuterium

The search for the the multineutron systems is old, but still unsettled problem of the low-energy nuclear physics. Numerous attempts of search for the existence of the tetraneutron as a bound or resonant state have been realized using multiple approaches (e.g. uranium fission reactions, pion-induced double-chargeexchange and transfer reactions). However, no certain evidence of tetraneutron existence have bee obtained.

The situation has changed with the recent studies of 4n population in reactions with 8He, where four neutrons can be found in a spatially-separated neutron-halo configuration. The result of the recent 1H(8He,pα) experiment [1] showed the population of the "resonance-like structure" at E(4n) = 2.37 MeV with Γ = 1.75 MeV.

In this work we demonstrate that an evidence for the low-energy structures analogous to the observation of [1] can be found in the other reactions with the 8He beam. The high intensity 8He secondary beam with energy 26 A MeV, produced at the ACCULINNA2 fragment separator [2], was used for the population of the tetraneutron in the 8He+d interaction. The detection the low-energy recoils 6Li and 3He made with high energy and angular resolution allowed us to reconstruct the tetraneutron missing-mass spectra in the two reactions: 2H(8He,6Li)4n and 2H(8He,3He)7H->3H+4n [3]. Both of these approaches provided evidence for a hump in the 4n continuum at about 3.5 MeV. The applied experimental techniques, the results of the data analysis and simulations are presented in the report, as well as possible theoretical interpretation of the data.

[1] M. Duer et al., Nature 606 (2022) 678–682.
[2] A.S. Fomichev, L.V. Grigorenko, S.A. Krupko, S.V. Stepantsov, G. M. Ter-Akopian, The EPJ A 54 (2018) 97.
[3] I.A. Muzalevskii et al., arXiv:2312.17354, Phys. Rev. C (in print).

Speaker: Ivan Muzalevskii (Joint institute for nuclear research)

Presentation_ID249_Muzalevskii.pdf

279 Experimental studies of the nuclear interactions in few-nucleon systems

The dynamics of the three-nucleon system can be extensively studied in the deuteron-proton (dp) system. Experimental investigations of the deuteron breakup in dp scattering allow for observing the effects of various dynamical components, such as the three-nucleon force (3NF) and the Coulomb force. Measurements of cross sections as well as polarization observables (e.g. vector and tensor analyzing powers [1]) enable rigorous testing of theoretical calculations based on various approaches [2–5] for modeling interactions in three-nucleon systems.
Additionally, studies of the $^1$H(d, pp)n reaction at low energies (e.g. 50 MeV/nucleon) are crucial for testing predictions of Chiral Effective Field Theory (ChEFT) [6].
The presentation will focus on the effects of the 3NF and the Coulomb force in the differential cross section for the dp breakup reaction, studied over a wide range of energies from 50 and 190 MeV/nucleon [8–11]. Moreover, our data will be presented in the invariant coordinate regime. The data collected at 50 MeV/nucleon will be compared with predictions from ChEFT [7].
Furthermore, information about ongoing and planned projects conducted at the Cyclotron Center Bronowice, PAS, Kraków, Poland, will also be discussed.

[1] E. Stephan, et al., Eur. Phys. J. A 49 (2013) 36.
[2] H. Witała, et al., Phys. Rev. Lett. 81 (1998) 1183.
[3] A. Deltuva, et al., Phys. Rev. C 68 (2003) 024005.
[4] S.A. Coon, et al., Few-Body Syst. 30 (2001) 131.
[5] A. Deltuva, et al., Phys. Rev. C 80 (2009) 064002.
[6] E. Epelbaum, et al., Eur. Phys. J. A 19 (2004) 125; ibid. A 19 (2004) 405.
[7] R. Skibiński, et al., private communication
[8] I. Skwira-Chalot, et al., Few-Body Syst. 65 (2024) 24.
[9] W. Parol, et al., Phys. Rev. C 102 (2020) 054002.
[10] A. Łobejko, et al., Few-Body Syst. 65 (2024) 36.
[11] B. Kłos, et al., Phys. Rev. C 101 (2020) 044001.

Speaker: Izabela Skwira-Chalot (Faculty of Physics, University of Warsaw, Warsaw, Poland)

Presentation_ID545_SkwiraCh.pptx

280 Few-Nucleon Scattering Experiment to Explore Three-Nucleon Forces

One of the main interests of nuclear physics is to understand
the forces acting between nuclear constituents.
Importance of the three-nucleon force (3NF) in the nuclear
Hamiltonian has been studied in few-nucleon systems
as well as in many-nucleon systems [1--3].

Nucleon--deuteron ($Nd$) scattering,
the three-nucleon ($3N$) scattering system,
offers a good opportunity
to study dynamical aspects of 3NFs, which are momentum,
spin and isospin dependent, since it provides
not only cross sections but also a variety of spin observables
at different incident nucleon energies.
Direct comparison between the experimental data
and the rigorous numerical calculations in term of Faddeev theory
based on the realistic bare nuclear potentials
provides information on 3NFs.
Indeed, the last two decades have witnessed the extensive experimental
and theoretical investigations of the $Nd$ scattering performed
in a wide range of incoming nucleon energies up to 300 MeV/nucleon.

The four-nucleon ($4N$) systems could also play an
important role in the study of 3NFs.
3NF effects are expected to be sizable in the $4N$ system.
In addition,
while the $Nd$ scattering is essentially a pure isospin $T=1/2$
state, tests of the $T=3/2$ channel in any 3NFs can
be performed in a $4N$ system such as proton-$^3$He scattering.
In recent years, there has been a large progress in
solving $4N$ scattering problem with realistic Hamiltonian
even above four-nucleon breakup threshold energies [4],
which opens up new possibilities of approaching to
properties of 3NFs.

With the aim of exploring the 3NFs
experimental programs of deuteron--proton scattering
as well as proton--$^3¥rm He$ scattering
using the polarized beam and target systems
are in progress at RIKEN, RCNP, and CYRIC in Japan.
In the conference, we introduce recently conducted experiments
and present the results of comparison between the
experimental data and the theoretical predictions
based on the realistic bare nuclear potentials.
Parts of the results are published in Refs.[5,6].

{¥small
¥indent
{[1]} W.¥ Gl¥"ockle, {¥it et al.} Phys.¥ Rep.¥ {¥bf 274}, 107 (1996).¥¥
¥indent
{[2]} K. Hebeler, Phys. Rep. {¥bf 890}, 1 (2021).¥¥
¥indent
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}

Speaker: Prof. Kimiko Sekiguchi (Institute of Science Tokyo)

Presentation_ID103_Sekiguchi.pdf

281 Measurement of proton-3He elastic scattering at intermediate energies

The three-nucleon force (3NF) is essentially important to describe nuclear properties, such as the binding energy of light mass nuclei, the equation of state of nuclear matter and few-nucleon scattering systems. The isospin $T=3/2$ components of the 3NF also play an important role in many-nucleon systems especially for neutron-rich nuclei as well as neutron matter properties. Proton-$^3$He ($p$-$^3$He) scattering is one of the simplest prove for studying the $T=3/2$ components of the 3NF.

We present the measurement of $p$-$^3$He elastic scattering at intermediate energies using the polarized beam and target systems. High precision data for the cross section $d\sigma/d\Omega$, proton and $^3$He analyzing powers, and spin correlation coefficient $C_{y,y}$ at 50--100~MeV, are compared with rigorous numerical calculations of 4N scattering based on various NN potentials. Large differences are seen in the regime around the cross section minimum for almost of observables. We also compared the data with the calculations based on the CD-Bonn+$\Delta$ potential which allows an excitation of a nucleon to a $\Delta$ isobar. As a result, the discrepancies were partially improved for some observables, but it was not resolved for most of the observables, including the cross sections. This is a different property from that of the 3N scattering, suggesting the validity of the 4N scattering as an experimental tool. In the conference we report the recent results of these experiments and discussions.

Speaker: Atomu Watanabe (Institute of Science Tokyo)

Parallel Session: 5_Nuclear Reactions (2)

Convener: Kouichi Hagino (Kyoto University)

282 Model-independent measurement of isospin diffusion at Fermi energies with INDRA-FAZIA: towards new quantitative constraints on symmetry energy

Heavy ion reactions provide a unique opportunity to gain insight in the equation of state of baryonic matter over varying densities, but many delicate aspects must be taken into account in order to get quantitative constraints through the comparison with trasport model predictions, including, e.g., a proper choice of the observables, and their evaluation in similar conditions between experimental and simulated data. In particular, a proper treatment of the reaction centrality is crucial to take care of the latter aspect.

In this contribution we present a model-independent experimental measurement of the effect of isospin diffusion in $^{58,64}$Ni+$^{58,64}$Ni collisions at 32 MeV/nucleon, studied directly as a function of the impact parameter. This result has been obtained by combining two datasets having common characteristics, but bearing complementary information. The first dataset has been acquired with the INDRA setup [1] and used to implement a model-independent reconstruction of the impact parameter [2], while the second one has been acquired in the first experimental campaign of the coupled INDRA-FAZIA apparatus at GANIL [3-5]. The neutron-to-proton content of the quasiprojectile remnant measured by FAZIA [6,7] has been employed as isospin observable. The isospin transport ratio technique [8] has been employed to highlight the effect of isospin diffusion, and the evolution towards equilibration as a function of the impact parameter of the collision is clearly extracted [9].

The experimental result is then compared to model predictions based on the BUU@VECC-McGill transport model [10], where, by exploiting the metamodeling technique of Ref.[11], different parametrizations of the Nuclear Equation of State available in the literature have been considered, including two extreme $\chi$-EFT interactions: a good agreement is found within the chiral constraint [12]. Further details of the diffusion process, including the densities explored by the system during the collision, have been also studied in the framework of the BUU@VECC-McGill model.

References

[1] J. Pouthas et al., Nucl. Instr. Meth. A 357, 418 (1995), J. Pouthas et al., Nucl. Instr. Meth. A 369, 222 (1996)
[2] J. D. Frankland et al., Phys. Rev. C 104, 034609 (2021)
[3] G. Casini and N. Le Neindre, Nucl. Phys. News 32, 24 (2022)
[4] C. Ciampi et al., Phys. Rev. C 106, 024603 (2022)
[5] C. Ciampi et al., Phys. Rev. C 108, 054611 (2023)
[6] R. Bougault et al., Eur. Phys. J. A 50, 47 (2014)
[7] S. Valdrè et al., Nucl. Instr. and Meth. A 930, 27 (2019)
[8] F. Rami et al., Phys. Rev. Lett. 84, 1120 (2000)
[9] C. Ciampi et al., in preparation
[10] S. Mallik et al., J. Phys. G: Nucl. Part. Phys. 49, 015102 (2021)
[11] J. Margueron et al. Phys. Rev. C 97, 025805 (2018)
[12] S. Mallik, C. Ciampi et al., in preparation

Speaker: Caterina Ciampi (GANIL)

Presentation_ID158_Ciampi.pdf

283 Experimental study of photoactivation in proton-enriched $^{113}In$, $^{112}Sn$, and $^{114}Sn$ nuclei and their contributions to the ${\gamma}$-process.

The vast majority of chemical elements and their stable isotopes observed in nature, located in the medium- and heavy-mass regions, were synthesized in hot stars as a result of nuclear reactions. The processes responsible for synthesizing most of the nuclei of these isotopes are called rapid ($r$-process) and slow ($s$-process) neutron capture processes, i.e., (n,$\gamma$)-reactions [1]. However, within the medium- and heavy-mass regions, there are 35 $p$-nuclei, including the $^{113}In$, $^{112}Sn$, and $^{114}Sn$ nuclei. A dominant role in the formation of $p$-nuclei is played by low-energy photonuclear reactions such as ($\gamma$,n), ($\gamma$,p), and ($\gamma$,$\alpha$).
To model the natural abundances of $p$-nuclei, knowledge of a large array of reaction rates is required, which can be obtained from cross-sections or yields. Using bremsstrahlung $\gamma$-quanta from a tantalum converter, an irradiated beam of the Linear electron accelerator at the National Science Center "Kharkiv Institute of Physics and Technology", and the activation technique with high-energy gamma spectrometry, we measured the cross-sections of the reactions $^{113}In$($\gamma$,n)$^{112m}In$, $^{113}In$($\gamma$,n)$^{112g}In$, $^{112}Sn$($\gamma$,n)$^{111}Sn$, $^{112}Sn$($\gamma$,p)$^{111m}In$, $^{112}Sn$($\gamma$,p)$^{111g}In$, and $^{114}Sn$($\gamma$,n)$^{113}Sn$ in the energy range from the threshold up to 15 MeV.
The results of the experimental measurements are compared with existing data in the literature and with calculations from the statistical theory of nuclear reactions, implemented in the computer codes NON-SMOKER [2] and TALYS [3] (v. 2.0), using different models for nuclear level density and radiative strength functions.
A series of measurements of the energy spectra of $\gamma$-decay quanta with different cooling times and the individual decay scheme of the $^{111}Sn$ nucleus allowed us to calculate new values of the branching coefficients for the nine strongest transitions accompanying the decay of $^{111}Sn$. These values differ from the baseline values currently adopted, with an average weighted coefficient of 1.38 (±0.08).
This finding suggests the need to revise certain published experimental cross-section values for nuclear reactions in which the $^{112m}In$ and $^{111}Sn$ nuclides are the residual product.

Speaker: Dr Anastasiia Chekhovska (Institute for Basic Science, National Science Center “Kharkiv Institute of Physics and Technology”)

Anastasiia Chekhovska_INPC 2025 (Daejeon).pptx

284 Progress in development of the γ-ray emission cross-section database for reactions with 14 MeV neutrons

Information about the elemental composition of various objects is in demand in various industries. One way to obtain it is elemental analysis using fast or high-energy neutrons. The main advantage of this method is the high penetrating power of fast neutrons. The usage of compact D-T neutron generators with an energy of 14.1 MeV makes it possible to create compact portable setups, as well as to implement the method of tagged neutrons by detecting the accompanying alpha particle emitted in the T(D,n)a reaction.
To date, one of the main obstacles to the wide application of this technique is the lack of a relevant database on the radiation cross sections of the characteristic gamma lines from the nuclei of various elements. The currently available information is replete with inaccuracies and incomplete (Simakov S.P. et al. IAEA, 1998): the uncertainty in the emission cross section of the most intense gamma line can reach 300%, data for low-intensity (<6 mb) gamma lines are not available. A large number of chemical elements, remain unexplored.
In 2023 in FLNP JINR we have started a project dedicated to measurements of γ-ray emission cross sections and angular distributions in neutron-induced reactions for 55 elements. To date, data for 27 elements is acquired. Also software development is going on for EXFOR processing and estimation of γ-quanta emission cross-sections from already existed data.
In proposed report a review of achieved results will be presented.

Speaker: Nikita Fedorov (JINR)

Presentation_FedorovN.pdf

285 Experimental signature of entrance channel effect for mass region A ∼ 200

The fusion of heavier mass nuclei is a complex process significantly influenced by the entrance channel of the colliding nuclei. Notably, the mass asymmetry of the colliding nuclei can impact the fusion process, with symmetric systems often exhibiting inhibited fusion compared to asymmetric ones, particularly in the mass region around 200 [1,2]. Evaporation residues (ERs) are considered a definitive indicator of fusion, as their formation necessitates the nuclei to traverse the compound nucleus (CN) phase. This makes them a sensitive probe to study the entrance channel effect in the presaddle region. In this work, we aimed to understand these underlying effects through the measurements of ER cross-sections and ER-gated spin distributions [3,4] for two different reactions: $^{48}$Ti + $^{160}$Gd and $^{30}$Si +$^{178}$Hf. Both reactions form the same compound nucleus, $^{208}$Rn. These measurements were conducted using the HYbrid Recoil Mass Analyzer (HYRA) coupled with the TIFR 4$\pi$ spin spectrometer at the Inter University Accelerator Centre (IUAC), New Delhi [5]. Beams of $^{48}$Ti and $^{30}$Si were pulsed to provide the width of $\sim$1 ns with the separation of 250 ns and 2 $\mu$s respectively. Isotopically enriched thin targets of $^{160}$Gd ($\sim$220 $\mu$g/cm$^2$ ) and $^{178}$Hf ($\sim$130 $\mu$g/cm$^2$ ) were bombarded with ion beams at nine different energies. The energies ranged from around the Coulomb barrier to 20$\%$ above the barrier. The magnetic field and gas pressure of the HYRA were optimized to maximize the transmission of ERs to the focal plane. The ERs were detected using the position sensitive multiwire proportional counter (MWPC) positioned at the focal plane of HYRA. The closely packed array of 29 NaI detectors was mounted around the target chamber to capture the gamma rays emitted. The total solid angle covered by the 4$\pi$ multiplicity array is $\sim$86$\%$ [6]. $\\$

ER yields were extracted from the two dimensional coincidence spectrum between energy loss ($\Delta E$) and time of flight (TOF) of ER . From an experimentally measured $\gamma$ fold, ER-gated $\gamma$ multiplicity distribution was extracted. Our initial analysis indicates a significantly lower ER cross-section for the more symmetric system, $^{48}$Ti + $^{160}$Gd , compared to the $^{30}$Si + $^{178}$Hf. This clearly demonstrates that the outcome of the fusion process is influenced by the specific choice of the entrance channel. Further analysis of the spin distribution measurements is currently underway.

1. A. C. Berriman $\textit{et al.}$, Nature (London) ${\bf 413}$,144 (2001).
2. N. Kumar ${\textit {et al.}}$, Phys Lett. B ${\bf 214}$, 136062 (2021).
3. G. Mohanto ${\textit {et al.}}$, Phys. Rev. C ${\bf 88}$, 034606 (2013).
4. W. Ye, Phys. Rev. C ${\bf 83}$, 044611 (2011).

5. N. Madhavan ${\textit {et al.}}$, Pramana ${\bf 75}$, 317 (2010).

6. R. Sariyal ${\textit {et al.}}$, Phys. Rev. C ${\bf 110}$, 044610 (2024).

Speaker: Mr Phurba Sherpa (Department of Physics & Astrophysics, University of Delhi, Delhi 110007, India)

Presentation_ID313_Sherpa.pdf

286 Measurement of $^{27} {\rm{Al}}(p,\gamma)^{28} {\rm{Si}}$ reactions near 2 MeV

We developed a LaBr$_3$(Ce) detector array (HANULball) to measure gamma rays with energies up to 10 MeV. The HANULball consists of 10 LaBr$_3$(Ce) detectors arranged in a truncated cuboctahedron structure, each coupled with a photomultiplier tube for detecting scintillation light. Using a 2-MV tandem ion accelerator at KIST, we measured gamma rays from the $^{27} {\rm{Al}}(p,\gamma)^{28} {\rm{Si}}$ reaction over the proton energy range of $E_p=2.040$ to $E_p=2.080$ MeV. Additionally, we conducted simulation studies to evaluate the detection efficiency of the LaBr$_3$(Ce) detectors. We will discuss the performance of the HANULball detector system and its detection efficiency across a wide range of gamma-ray energies.

Speaker: Young Jun Kim (Korea University)

Presentation_ID559_Kim.pdf

287 Investigating $\beta^+$ decay/EC mode in $^{12}$C+$^{118}$Sn reaction residues

Different decay modes of complete/incomplete fusion and pre-equilibrium have been investigated in $^{12}$C+$^{118}$Sn system. The channel-by-channel fusion cross-sections of $^{126}$Ba ($4$n), $^{127,126,125}$Cs (p$x$n), $^{125,123,122}$Xe ($\alpha$$x$n) and $^{124,123}$I ($\alpha$p$x$n) residues have been measured at E$_{\textrm{lab}}$ $\approx$ 65-85 MeV [1]. Experimentally measured cross-sections have been analyzed in the framework of theoretical model codes PACE4 and EMPIRE. In this work, The cross-sections of p$x$n ($^{127,126,125}$Cs), $\alpha$xn ($^{125}$Xe), and $\alpha$p$x$n ($^{123}$I) channels have been found to be substantially fed from their higher charge isobars via $\beta^+$ decay/EC. In order to deduce the contribution of higher charge isobars in the population of these residues, the independent cross-sections of evaporation residues have been calculated using the prescription of Cavinato et al.[2] and compared with theoretical model codes. It has been found that the PACE4 and EMPIRE calculations fairly reproduce the independent cross-sections of evaporation residues.

Interestingly, it has been found that the $\alpha$-emitting channels, contrary to established findings in reactions involving $\alpha$-cluster projectiles (e.g., $^{12}$C, $^{16}$O, etc.) at low incident energies, shows zero, or negligible contribution from incomplete fusion. To validate the findings of the excitation functions, forward ranges of recoils for reactions $^{118}$Sn($^{12}$C,$x$n), $^{118}$Sn($^{12}$C,p$x$n), $^{118}$Sn($^{12}$C,$\alpha$xn) and $^{118}$Sn($^{12}$C,$\alpha$p$x$n) have been measured at beam energy of E$_{\textrm{lab}}$ $\approx$ 78.9 MeV. This disentangles different processes in $^{12}$C + $^{118}$Sn system by analyzing full and partial linear momentum transfer, and presents the relative contributions of compound nucleus, reduced compound nucleus and precompound processes. Experimental data and its analysis suggest unique behavior of this system. Detained results will be presented during the conference.

[1] Priyanka et al., Phys. Rev. C. (under review) https://arxiv.org/abs/2410.03691

[2] M. Cavinato, E. Fabrici, E. Gadioli, E. G. Erba, P. Vergani, M. Crippa, G. Colombo, I. Redaelli, and M. Ripamonti, Phys. Rev. C 52, 2577 (1995).

Speaker: Ms Priyanka Priyanka (Department of Physics, Indian Institute of Technology Ropar, Rupnagar - 140 001, Punjab, India)

Presentation_ID613_Priyanka.pdf

Parallel Session: 5_Nuclear Structure (1)

Convener: Heather Crawford (Lawrence Berkeley National Laboratory)

288 Latest results on gamma spectroscopy with AGATA

The study of nuclear structure around and away from the valley of stability has led to the discovery of new phenomena, such as the occurrence of new shapes, new shell closures and shape coexistence. The detailed study of these features require the use of state-of-the-art gamma spectrometers, such as the AGATA gamma-ray tracking array, providing the highest detection efficiency and position sensitivity, crucial to pin down weak signals.
The Advanced GAmma Tracking Array (AGATA)[1] is a major European project, involving over 40 institutes in 12 countries, to develop and operate a high-resolution gamma-ray tracking spectrometer.
AGATA is a travelling instrumentation visiting the major European laboratories, GANIL (Fr) [2], GSI-FAIR (D) and INFN-LNL (I) [3].
In this talk the main features of the AGATA array will be presented, together with highlights on recent technical developments and analysis procedures. Examples of experimental campaigns at the 3 main european laboratories will be discussed, with a look forward to future campaigns.

[1] S. Akkoyun et al., Nucl. Instrum. Methods Phys. Res. A 668, 26 (2012). https://doi.org/10.1016/j.nima.2011.11.081
[2] E. Clément et al., Nucl. Instrum. Methods Phys. Res. A 855,1 (2017). https://doi.org/10.1016/j.nima.2017.02.063
[3] J.J. Valiente-Dobón et al., Nucl. Instrum. Methods Phys. Res. A 1049, 168040 (2023). https://doi.org/10.1016/j.nima.2023.168040

Speaker: Giovanna Benzoni (INFN-Milano)

Presentation_ID637_Benzoni.pdf

289 Evidence for the coexistence of chiral doublet bands and stapler band in 81Br

High spin states of odd A 81Br were populated using the 82Se(4He, p4n) reaction with the beam energy of 65 and 68 MeV. A pair of nearly degenerate negative parity bands were observed in this nuclues, as well as a negative parity dipole band. Based on the experimental characters of these bands, they were respectively interpreted as a pair of chiral doublet bands based on the π(fp, g9/2g9/2) configuration and a stapler band. The interpretation was supported by the multiparticle rotor model and the self-consistent tilted axis cranking covariant density functional theory calculations. The present work suggests a new chiral configuration in the nuclear system, and provides the evidence for the coexistence of chiral doublet bands and stapler band in 81Br.

Speaker: Chen Liu (Shandong University, Weihai)

Presentation_ID105_Liu.pptx

290 Investigation of the structure of the lowest quadrupole excitations in Ge isotopes

At present, a lot of experimental information has been accumulated on the structure of low-lying excited states in Ge isotopes. Interest in these nuclei is due to the fact that with an increase in the number of neutrons there is a transition between spherical and deformed forms of the nucleus that determine their structure. On the other hand, microscopic calculations show that Ge isotopes are soft in relation to triaxial deformation. In this report, we analyze the properties of low-lying 2+ states in isotopes of 70-88Ge. Calculations were carried out by constructing and diagonalization of the collective quadrupole Hamiltonian. The surfaces of potential energy and mass parameters were calculated in the relativistic mean field model with two parameterization of the energy density functional: PC-PK1 and NL3. The results of the calculations are compared with the experimental data and the results obtained within other approaches.

Speaker: Evgenii Mardyban (JINR)

Presentation_ID73_MardybanE.pptx

291 l-forbidden M1 transitions in N=50 isotones

The occurrence of pairs of nuclear states at low energy, differing in orbital angular momentum by two units and corresponding to single-particle states within the nuclear shell model, is frequently observed in odd-mass nuclei located near closed shells across the nuclear chart. Such single-particle states experimentally observed as the ground state and low-lying first-excited state in many odd-A nuclei across several mass regions. They can be labelled with the radial quantum number nr, the orbital angular momentum l and the total angular momentum j, and correspond to |n$_r$ l j=l+1/2> and |n$_r$–1 l+2 j´=l+3/2>, respectively, for example the pairs s$_{1/2}$ – d$_{3/2}$, p$_{3/2}$ – f$_{5/2}$ and g$_{7/2}$ – d$_{5/2}$.

Magnetic dipole M1 $\Delta$l=2 transitions between pairs of states of this kind are l-forbidden in the extreme shell model picture [1,2] because the magnetic dipole isovector operator does not change the orbital angular momentum. Nonetheless, such transitions are still experimentally observed, although with rates that are generally much lower than those of allowed transitions, or even below the single-particle limit. It is expected that these transitions result from the breakdown of l-forbiddenness, influenced by other nuclear dynamic effects, such as core polarization and meson exchange mechanisms [3]. Therefore the investigation of l-forbidden M1 transitions may provide insight into the role of these effects within the atomic nucleus [4].

Semimagic nuclei with Z = 50 [5,6] and N = 50 [7] with varying number of neutrons or protons, respectively, are excellent laboratories to probe l-forbidden M1 transitions. The presentation will focus on odd-A N = 50 isotones in the vicinity $^{78}$Ni, where the M1 transitions probabilities are obtained from excited level lifetime measurements employing fast-timing methods. New results will be presented for $^{83}$As, $^{85}$Br, obtained from experiments performed at ISOLDE/CERN and ILL, respectively. They will be discussed in the context of other available data for the region, completing the systematics from $^{81}$Ga to $^{87}$Rb where the dominant single-particle configurations are due to the p$_{3/2}$ and f$_{5/2}$ orbitals in the 28–50 proton shell. The results will be compared to shell model calculations in order to understand the role of the occupation of the proton orbitals and core polarization effects [8].

[1] I.M. Govil and C.S. Kurana, Nuclear Physics 60 (1964) 666.
[2] R.G. Sachs and M. Ross, Phys. Rev. 84 (1951) 379.
[3] W. Andrejtscheff, L. Zamick, N.Z. Marupov et al., Nuclear Physics A 351 (1981) 54.
[4] P. von Neumann-Cosel and J. N. Ginocchio, Phys. Rev. C 62 (2000) 014308.
[5] R. Lica, H. Mach, L.M. Fraile et al., Phys. Rev. C 93 (2016) 044303.
[6] J. Benito, L.M. Fraile, A. Korgul et al., Phys. Rev. C 110 (2024) 014328.
[7] V. Paziy, L.M. Fraile, H. Mach et al., Phys. Rev. C 102 (2020) 014329.
[8] Horie and Arima, Prog. Theor. Phys. 11 (1954) 509.

Speaker: Luis Mario Fraile (Universidad Complutense de Madrid)

fraile_INPC2025_lforbidden_250524r.pdf

292 Beta decay of selenium isotopes near N=50 shell closure

The nuclides 84,86Se lie near N~50 and halfway between 78Ni and 90Zr in a neutron-rich region of high interest. Beta decay and nuclear structure information of populated excited levels can give a valuable benchmark for nuclear theories to understand nucleon-nucleon interaction in this region. However, curiously, for certain selenium isotopes the beta decay has been little studied, actually less than most other nuclides that lie just few neutrons outside the valley of stability. The decay of neutron-rich Se isotopes had been studied five decades ago, either with chemically separated sources, i.e., a mixture of all selenium isotopes where detected γ-rays are only assigned to individual isotopes via their decay time, or with the gas-filled recoil separator JOSEF. At the time, no γγ-coincidences or conversion electrons could be measured. Selenium is a challenging element for ISOL facilities, which explains why pure and intense beams of neutron-rich Se isotopes are not yet available.
Beams of neutron-rich 84,86Se were produced by thermal neutron-induced fission of 235U at Institut Laue-Langevin. The beams of interest were mass and energy separated by the LOHENGRIN separator. At the focal plane the ions were implanted into a thin stopper foil and decays were measured using two experimental setups: (i) a -e- spectroscopy setup comprising two HPGe clover detectors and one Si(Li) detector, and (ii) a fast-timing setup consisting of four LaBr3 detectors. A new energy level in 84Br has been identified, and log ft values to and lifetimes of excited levels in 84Br have been measured. Preliminary results of several lifetimes of excited states of 86Br will also be presented. Finally, the measured log ft values and lifetimes are compared with shell-model calculations and second Tamm-Dancoff approximation (STDA) model predictions.

Speaker: Yung Hee KIM (CENS)

Beta decay of selenium isotopes near N50 shell closure_new5.pptx

Parallel Session: 5_Nuclear Structure (2)

Convener: Atsushi Tamii (Research Center for Nuclear Physics, Osaka University)

293 First laser-spectroscopy measurements across N = 32 in the calcium isotopic chain at the COLLAPS setup at ISOLDE/CERN

on behalf of the COLLAPS collaboration

Over a decade ago, the first experimental evidence for the N=32 sub shell closure in the calcium isotopic chain emerged [1,2]. Subsequent experimental and theoretical investigations have confirmed this finding. However, in laser spectroscopy measurements extending up to $^{52}$Ca (N=32), no indications of this shell gap were apparent [3]. Crossing the shell gap with laser spectroscopy setups has proved difficult due to the simultaneous requirement of a sensitivity of approximately 10 ions/s and a measurement uncertainty on the order of MHz.

This contribution presents the first laser spectroscopy measurements of $^{53,54}$Ca, facilitated by an extension of the collinear laser spectroscopy technique employed at the COLLAPS setup at ISOLDE/CERN. This technique, termed as \textit{radioactive detection after optical pumping and state selective charge exchange} (ROC), combines the high sensitivity of a particle detection scheme with the high resolution of low-power, continuous wave lasers utilized in a collinear geometry. The methodology of this technique will be explained, followed by the presentation and discussion of preliminary values for the magnetic dipole moment of $^{53}$Ca and the charge radii of $^{53,54}$Ca in the context of the robustness of the N=32 sub shell closure, as well as future perspectives of continuous beam CLS experiments with single-particle-per-second sensitivity.

[1] Wienholtz, F. et al. Nature vol. 498, 346-349 (2013)
[2] Steppenbeck, D. et al. Nature vol. 502, 207-210 (2013)
[3] R.F. Garcia Ruiz et al, Nature Physics vol. 12, 594-598 (2016)

Speaker: Tim Enrico Lellinger (Max Planck Institute for Nuclear Physics)

Presentation_ID621_Lellinger.pptx

294 Absolute radii extraction of chlorine and potassium isotopes

Muonic atom spectroscopy is a technique that studies the atomic transitions between levels that may be occupied by a muon orbiting a nucleus. Due to the heavier mass of the muon with respect to that of the electron, its atomic orbitals will be substantially closer to the nucleus. Consequently, the sensitivity to nuclear effects is enhanced. In particular, muonic atoms have an increased sensitivity to the finite size correction (~107 compared to electronic atoms). As a result, absolute nuclear charge radii can be extracted, providing invaluable input for laser spectroscopy experiments in the form of benchmarks [1].

By employing a high-pressure hydrogen cell, with a small deuterium admixture, it became possible to reduce the required target quantity from 10 mg to about 5 µg. This opens the door to measurements on long-lived radioactive isotopes and materials not available in large quantities [2]. In 2022, we performed an experiment that showed that implanted targets could be used for the spectroscopy [3]. As a result, samples that have been prepared by employing mass separation and subsequent implantation, can be measured with our technique. Following this success, we did another experimental campaign in October 2023 with the goal of measuring the absolute charge radius of potassium and chlorine isotopes.

In this contribution, we shall report on recent results obtained for muonic x-ray measurements on 39, 40, 41K and 35, 37Cl, as well as their implication for future research.

Speaker: Michael Heines (KU Leuven)

Presentation_ID371_Heines.pptx

295 Commissioning of the CLaSsy system at RAON

CLaSsy is an experimental setup designed for laser spectroscopy of radioactive isotopes at the RAON Isotope Separation On-Line (ISOL) facility of the Institute for Rare Isotope Science (IRIS). Laser spectroscopy provides access to mean-square charge radii through isotope shift measurements and extraction of nuclear magnetic dipole and electric quadrupole moments from hyperfine structure analysis. Recently, we have successfully observed the optical D1 and D2 transitions for $^{21,22,23}$Na isotopes in the form of bunched beam provided by the Radio Frequency Quadrupole-Cooler Buncher (RFQ-CB) at the ISOL facility. For stable $^{23}$Na, we obtained the hyperfine splitting of the ground states of 3$^2$S$_{1/2}$ of 1.77 GHz with the FWHM for individual peaks approximately 200 MHz at the ion beam energy of 20 keV. In particular, we employed both collinear and anti-collinear geometry to calibrate the ion beam energy, which allows accurate isotope shift measurements. In this talk, we will present the results of the recent commissioning of the CLaSsy system and an outlook on future experiments.

Speaker: Ms Chaeyoung LIM (IRIS, IBS / Korea University Sejong)

Presentation_ID550_Chaeyoung.pdf

296 Laser spectroscopy of Al and Ni as probes of the transitional regions of deformation at N = 20 and N = 40

The neutron-rich regions of $N~=~20$ and $N~=~40$ provide excellent testing grounds to investigate the evolution of nuclear structure and the rapid onset of deformation in radioactive isotopes lying close to shell closures and sub-shell closures. In these regions, effects such as islands of inversion (IoI), the onset of deformation and the collapse of the conventional shell model can be investigated using laser spectroscopy.

The Al isotopic chain forms the northern border of the $N~=~20$ island of inversion, presenting an ideal candidate to probe the transition from spherical Si [1] into deformed Mg [2], whereby $^{32}$Mg is considered the heart of the IoI. Before this work, charge-radii measurements in this region were limited up to $N~=~20$ for Mg [2] and Na [3], and $N~=~19$ for Al [4]. The CRIS collaboration recently measured $^{26-34}$Al using laser spectroscopy, crossing the $N~=~20$ shell closure.

The neutron-rich chain of Ni is of particular interest, with a magic proton number ($Z~=~28$) and spanning across two main shell closures ($N~=~28,~50$) and one sub-shell closure ($N~=~40$). However, the neutron-rich region of Ni marks a challenging area experimentally, due to the refractive nature of Ni and the large contamination in this region (Ga), resulting in the current laser spectroscopy studies being limited up to $^{70}$Ni (excluding $^{69}$Ni). However, this region, yet to be explored thoroughly with laser spectroscopy, marks an area of high interest. Measurements of the $E(2^{+})$ in Ni [5] indicate the re-emergence of the $N~=~40$ shell closure, which appears to collapse in neighbouring elements (Z < 28) such as Cr [6], forming the $N~=~40$ IoI. Furthermore, the enhancement of collectivity between $N~=~40-50$ induced by the weakening of the $Z~=~28$ shell closure [7] is not indicative of a semi-magic nucleus. The PI-LIST collaboration is actively working on the measurement of the neutron-rich chain of Ni using in-source laser spectroscopy, extending measurements into this mid-shell region between $N~=~40-50$.

In the first half of this talk, a brief overview of the CRIS technique will be presented along with recent measurements of the change in mean-square charge-radii of $^{33, 34}$Al, crossing $N~=~20$. In the second half, the PI-LIST technique will be introduced, followed with a presentation of the recent measurements on neutron-rich Ni, extending the measurements of the nuclear spin, charge-radii and electromagnetic moments into the $N~=~40-50$ mid-shell region. All result will be discussed in relation to the region and neighbouring isotopic chains.

[1] R. W. Ibbotson et al., Quadrupole Collectivity in 32,34,36,38Si and the N = 20 Shell Closure, Phys. Rev. Lett. 80 (1998) 2081-2084

[2] D. Yordanov et al., Nuclear charge radii of $^{21-32}$Mg, Phys. Rev. Lett 108 (2012), 042504

[3] G. Huber et al., Spins, magnetic moments, and isotope shifts of $^{21-31}$Na by high resolution laser spectroscopy of the atomic D1 line, Phys. Rev. C 18 (1978), 2342-2354

[4] H. Heylen et al., High-resolution laser spectroscopy of $^{27-32}$Al, Phys. Rev. C 103 (2021), 014318

[5] R. Taniuchi et al., $^{78}$Ni revealed as a doubly magic stronghold against nuclear deformation. Nature, 569 (7754):53 - 58, 5 2019.

[6] L Lalanne et al., $^{61}$Cr as a Doorway to the N = 40 Island of Inversion. arXiv:2409.07324, 2024

[7] T. Marchi et al., Quadrupole transition strength in the $^{74}$Ni nucleus and core polarization effects in the neutron-rich Ni isotopes. Phys. Rev. Lett., 113:182501, Oct 2014

Speaker: Jordan Reilly (CERN)

Presentation_ID624_Reilly.pptx

297 Charge symmetry breaking effects with $\omega$-$\rho^0$ mixing

One of the primary goals of nuclear physics is to achieve a unified understanding of baryon-baryon interactions based on flavor symmetry and its breaking. Charge symmetry breaking (CSB) represents a part of the flavor symmetry that is violated by nuclear forces, leading to differences in neutron-neutron and proton-proton interactions, as well as in neutron-Lambda and proton-Lambda interactions. The CSB effects are indeed observed in the mirror binding energy differences of both normal nuclei and hypernuclei [1-3].

In this work, we introduce CSB through $\omega$-$\rho^0$ mixing [4] within a relativistic mean-field model, along with corrections for electromagnetic (EM) interactions (such as the EM form factors of nucleons and vacuum polarization). An advantage of our model is its applicability to hypernuclei on an equal footing with normal nuclei. In this talk, we focus on normal nuclei and examine the effects of $\omega$-$\rho^0$ mixing on observables such as binding energy and charge radius.

[1] Nolen and Schiffer, Ann. Rev. Nucl. Sci. 19, 471 (1969).
[2] Botta, AIP Conf. Proc. 2130, 030003 (2019).
[3] Brown, Phys. Lett. B483, 49 (2000).
[4] Coleman and Glashow, Phys. Rev. Lett. 6, 423 (1961).

Speaker: Yusuke Tanimura (Soongsil University)

Presentation_ID657_Tanimura.pdf

298 A novel laser spectroscopy technique for measuring Mg charge radii in the N=20 island of inversion

The assumption of universal magic numbers, i.e. closed nuclear shells, all across the nuclear chart has been a fundamental paradigm of the nuclear shell model. However, when exploring nuclides far away from stability, a disappearance of well-established shell closures can be encountered, which, for instance, manifests itself in the island of inversion around $N = 20$ [1]. Describing this shell evolution from first principles is a formidable task for nuclear theory. Recently, nuclear ab-initio methods have been able to expand their reach also into open shell nuclei. This advance now allows for ab-initio calculations of nuclear observables within the $N = 20$ island of inversion [2]. In order to deepen our understanding of this region of nuclides and challenge the predictive power of modern nuclear theory, experimental knowledge about the nuclear charge radii of neutron-rich magnesium (Z = 12) isotopes is crucial.

A powerful tool to access nuclear charge radii is collinear laser spectroscopy (CLS) [3]. However, to extend previous measurements up to $^{32}$Mg [4] and explore the more exotic isotopes $^{33,34}$Mg with very low production yields at radioactive ion beam facilities, more sensitive methods have to be envisioned. The novel Multi-Ion-Reflection Apparatus for Collinear Laser Spectroscopy (MIRACLS) at ISOLDE/CERN [5] combines the high spectral resolution of conventional fluorescence-based CLS with high experimental sensitivity. This is achieved by trapping ion bunches in a Multi-Reflection Time of Flight (MR-ToF) device, in which the ions bounce back and forth between two electrostatic mirrors. Hence, the laser-ion interaction time is increased with each revolution in the MR-ToF apparatus, while retaining the high resolution of CLS.

Very recently in November 2024, we had a successful experimental campaign were we measured hyperfine spectra of $^{33,34}$Mg. This oral contribution will introduce the MIRACLS concept and present the first preliminary data of Mg charge radii from the aforementioned measurement.

[1] T. Otsuka et al., Rev. Mod. Phys. 92, 015002 (2020)
[2] T. Miyagi et al., Phys. Rev. C 102, 034320 (2020)
S. J. Novario et al., Phys. Rev. C 102, 051303 (2020)
G. Hagen et al., arXiv:2201.07298 (2022)
[3] K. Blaum, et al., Phys. Scr. T152, 014017 (2013)
P. Campbell et al., Prog. Part. and Nucl. Phys. 86, 127-180 (2016)
X. Yang et al., Prog. Part. and Nucl. Phys. 129, 104005 (2023)
[4] D. T. Yordanov et al., Phys. Rev. Lett. 108, 042504 (2012)
[5] S. Sels et al., Nucl. Inst. Meth. Phys. Res. Sec. B, 463, 310–314 (2020)
V. Lagaki et al., Nucl. Inst. Meth. Phys. Res. Sec. A, 165663 (2021)
F. Maier et al., Nucl. Inst. Meth. Phys. Res. Sec. A, 167927 (2023)

Speaker: Franziska Maria Maier (FRIB)

Presentation_ID216_Maier.pptx

Parallel Session: 5_Nuclear Structure (3)

Convener: Andrea Jungclaus (IEM-CSIC)

299 Investigation of phenomena arising in medium-mass nuclei at the neutron dripline

The understanding of the nuclear forces at play inside the nucleus is one of the major goals of modern nuclear physics. In particular, the study of phenomena arising in nuclei located near or beyond the neutron dripline, such as shell evolution, deformation, halo formation, provides a wealth of information that challenge our current knowledge. The Facility for Rare Isotope Beams (FRIB) offers the unique opportunity to extend such studies to dripline nuclei in the medium-mass region thanks to higher beam intensities. The MoNA collaboration is leading such effort at FRIB by launching an ambitious experimental program aiming to investigate the structure of nuclei in the region and to reveal the mechanism behind the neutron-halo formation observed or predicted in some nuclei.
Updates on recent MoNA experiments and future planned studies will be presented. In particular, the use the MoNA neutron scintillator array to perform kinematically complete Coulomb-breakup measurement of key nuclei of interests will be discussed. This, in combination to reaction theory calculations, will allow for unambiguous determination of the Coulomb-breakup cross-section, neutron separation energy, and ground state configuration of halo nuclei in this rather uncharted region.
This work was supported by the U.S. DOE Office of Science, and used resources of the Facility for Rare Isotope Beams Operations which is a DOE User Facility under Award Number DE-SC0023633

Speaker: Aldric Revel (FRIB/MSU)

INPC_Revel_2025_1.pdf

300 Carbon and Oxygen isotopes in Nuclear Lattice Effective Field Theory

Recent development of nobel wave function matching method in nuclear lattice effective field theory enables accurate calculations of energy and radius of various nuclei with high fidelity Hamiltonian. We apply this method to the calculation of binding energies of Carbon and Oxygen isotopes up to dripline and discuss its implications.

Speaker: Young-Ho Song (IRIS, IBS)

Presentation_ID46_SONG.pptx

301 Reduction of the Z=6 spin-orbit splitting in $^{20}$O: Probing the effects of the tensor force.

Shell evolution is an emergent phenomena driven by the residual interactions, in particular by the monopole terms of the nuclear force. One of the most influencial ones is the tensor force, which is atractive between antialigned spin orbits (and viceversa), and is well known for the emergence of the N=16 in place of the traditional N=20 magic number in n-rich Oxygens [1]. Exploring the evolution of other gaps is crucial for a proper understanding of this term. In particular the evolution of the Z=6 gap has brought quite attention in recent years, as it has been claimed its prevalence in neutron-rich carbon isotopes [2], a result that contradicts the intuitive effect of the tensor force and theoretical predictions [3]. This result has also been questioned by later measurements [4].

In order to shed more light into this subject, the structure of $^{20}$O was investigated through the proton-removal d($^{20}$O, $^{3}$He) reaction. The experiment was performed in 2022 at the LISE3 spectrometer based at GANIL, which delivered a $^{20}$O beam at 35 $A$MeV with an intensity of 2$\cdot$10$^{4}$ pps to the the active target ACTAR TPC [5]. The energy of the particles leaving the active volume was measured in the Si pad detectors while the angle was obtained from the reconstruction of the tracks in the gas. The excitation energy spectrum was built with the missing mass technique. This experiment was the first transfer-reaction experiment ever acomplished with ACTAR TPC, and the first (d,$^{3}$He) reaction performed with an active target.

The low-lying structure of $^{19}$N revealed multiple $\pi$-hole states with $\ell$=1, which was determined from the differential cross-section. The determination of energy and C$^{2}$S for all the states allowed a direct determination of the Z=6 gap through the Baranger formula. Our results support a reduction of the gap due to the tensor force in agreement with theoretical predictions from [3] using the state-of-the art SFO-tls interaction.

References:

[1] C. R. Hoffman et al., Phys. Rev. Lett., 100, (2008),152502.
[2] D.T. Tran et al., Nature Communications, 9, (2018),1594.
[3] T. Otsuka et al. Phys. Rev. lett. 95, (2005), 232502.
[4] I. Syndikus et al., Physics Letters B, 809, (2020), 135748.
[5] B. Maus et al. Nucl. Instrum. Meth. Phys. Res. A 940, (2019), 01689002.

Speaker: Juan Lois Fuentes (FRIB/MSU)

Presentation_ID380_LoisFuentes.pdf

302 Nuclear structure beyond the proton dripline

The current studies of proton-unbound nuclei to be reviewed.
Nuclear structure beyond the proton drip line was addressed in a number of recent experimental and theoretical studies of the light- and intermediate- mass nuclei, see the recent review [1]. The present research status can be summarized as follows:

i) All known 1p and 2p emitters are located by 1–2 atomic mass units (amu) beyond the proton drip line. The 2p emitters exhibit three main decay mechanisms (direct, sequential and democratic) and their transition modes [2].

ii) The most exotic nuclei located in the very remote outskirts of the nuclear landscape become unbound in respect of new decay channels. Such exotic decay modes play an increasingly important role as the precursor’s decay energy grows. The most-remote isotopes are identified as far as 4 amu beyond the proton drip line and decay by emission of 3 or 4 protons.

iii) The studied 3p- and 4p- decays show sequential decay mechanisms like 1p–2p and 2p-2p emissions, respectively. In particular, there are several isotopes whose ground states (g.s.) are established as 3p emitters, i.e. 7B, 17Na, 31K, 13F, and the recently-observed 20Al [3]. The measured 3p-decay patterns in all cases include 2p emission as part of a sequential p–2p decay mechanism. This may strongly influence the predictions for unobserved-yet isotopes. More multi-proton decay modes are reported, i.e. 5p emission from 9N, and even 6p emission is foreseen from unobserved yet 20Si.

iv) Predictions for proton-unbound isotopes by using their neutron-rich mirrors and isospin symmetry indicate area of 5–6 amu beyond the proton drip line [4].

For the most remote nuclear systems, no g.s. of isotopes (and thus no new isotope identification) are expected. Therefore a new borderline indicating the limits of existence of isotopes in the nuclear chart and the transition to chaotic-nucleon matter may be discussed [5].

[1] M. Pfutzner, I. Mukha, and S.M. Wang, Prog. Part. Nucl. Phys., 104050 (2023).
[2] T. Golubkova, X.-D. Xu, L.V. Grigorenko, I. Mukha, C. Scheidenberger, M. Zhukov, Phys. Lett. B 762, 263 (2016).
[3] X.-D. Xu, I. Mukha et al., submitted to Phys. Rev. Lett.; arXiv:2412.08245.
[4] L.V. Grigorenko, I. Mukha et al., Phys. Rev. C 98, 064309 (2018).
[5] D. Kostyleva, I. Mukha et al., Phys. Rev. Lett. 123, 092502 (2019).

Speaker: Ivan Mukha (Helmholzzentrum GSI, Darmstadt, Germany)

Presentation_ID267_Mukha.pdf

303 Beta-delayed two-proton spectroscopy at FRIB

13 beta-delayed two-proton (β2p) emitters are known today: $^{22}\mathrm{Al}$, $^{22,23}\mathrm{Si}$, $^{26}\mathrm{P}$, $^{27}\mathrm{S}$, $^{31}\mathrm{Ar}$, $^{35}\mathrm{Ca}$, $^{39}\mathrm{Ti}$, $^{43}\mathrm{Cr}$, $^{45,46}\mathrm{Fe}$, $^{50,51}\mathrm{Ni}$. The Q-value (the energy released in the decay) is a major determining factor for what type of beta-delayed decays occur, and therefore two-proton emitters are found at or close to the dripline. Nuclear structure also plays a role as clustering in light nuclei evolves into competition between single particle and collective (rotational and vibrational) degrees of freedom. The cross-over happens in this interesting region of the chart of nuclei where the known β2p emitters are found. The relation between two-proton emission and many-body nuclear structure is still poorly understood.

Of the 13 known cases, only $^{31}\mathrm{Ar}$ has been studied with sufficient statistics and beam quality to provide a deep study of the mechanism of the two-proton emission, this being the only case possible to produce at an ISOL facility (ISOLDE-CERN). Short-lived isotopes of the elements between Mg and Cl are difficult, or impossible, to produce at ISOL facilities due to the chemical properties of those elements.

With FRIB coming on-line and the Gas Stopping Area working excellently it is now possible to make low energy beams of most of these isotopes with unprecedented yields. With FRIB Experiment 21010 on the decays of $^{22}\mathrm{Al}$ and $^{26}\mathrm{P}$ we have initiated the exploration of this fertile region of nuclear structure and decay phenomena. The experiment is the first successful FRIB Experiment conducted in the Stopped Beam Area with yields of the two species of respectively 10 and 60 particles per second. The experiment provided much improved data both in quality and quantity not only for $^{22}\mathrm{Al}$ and $^{26}\mathrm{P}$, but also for $^{21}\mathrm{Mg}$ and $^{25}\mathrm{Si}$ (beta-delayed one-proton emitters), which were present as contaminants and/or were used for calibration purposes.

In this contribution I will present results from FRIB Experiment 21010 including a clarification of the mechanism of two-proton emission in the decays of $^{22}\mathrm{Al}$ and $^{26}\mathrm{P}$. Plans for future studies at FRIB to address more of the 13 known cases of beta-delayed two-proton emitters will also be presented.

Speaker: Erik Jensen (Aarhus Universitet, Denmark)

Presentation Slides (PDF/PPT ONLY) Presentation_ID620_Jensen.pdf

304 Quenching of spectroscopic factors extracted from single-particle transfer reactions of unstable nuclei

Spectroscopic factors are generally quenched relative to the occupancy numbers predicted by the independent particle model(IPM) due to nucleon-nucleon correlations, which is quantified by the reduction/quenching factor Rs. Rs extracted from knock-out reactions were found to be strongly dependent on the isospin asymmetry (ΔS = Sn- Sp / Sp- Sn for neutron/proton removing reaction) [1]. However, Rs deduced from the transfer reactions induced by stable nuclei were found to be independent of ΔS[2]. How about Rs from the transfer reactions of unstable nuclei with larger absolute values of ΔS?
In order to answer this question, a combined experiment with radioactive beams of 15C and 16N was performed at Radioactive Beam Line in Lanzhou (RIBLL) in 2022[3,4]. The differential cross sections of the single-nucleon transfer reactions 15C(p, d)14C, 15C(d, 3He)14B, 16N(p, d) 15N, and 16N(d, 3He)15C were obtained. By comparing the experimental angular distributions to the DWBA theoretical calculations, the spectroscopic factors and the corresponding Rs with ΔS = -19.12-19.86 MeV were extracted. Weak dependencies of Rs on ΔS were found in the present experiment. Note that the recoil target-like light charged particles were measured in coincidence with the projectile-like heavy particle, which clearly exclude effects of other reaction channels. The most important thing is that these different transfer reaction channels were measured in one experiment using the same target, which can reduce the systematic errors of Rs.
A new resonance at about Ex = 6.0 MeV in 14B which may correspond to the 1_2^- state predicted by shell model was observed from the 15C(d,3He)14B reaction[5]. Together with the spectroscopic factors of 1_1^-, 2_1^-, 2_2^- states extracted from the 15C(d,3He)14B reaction, all the spectroscopic factors were normalized according to the sum rule, and the normalization factor was found to be consistent with stable nuclei [2]. The effect of halo structure in 15C on the quenching factors[6] of 15C(d,3He)14B and 15C(p, d)14C was also carefully discussed[7].
[1] J. A. Tostevin, A. Gade, Phys. Rev. C, 2021, 103, 054610.
[2] B. P. Kay, J. P. Schiffer, S. J. Freeman, et al., Phys. Rev. Lett. 2013, 111: 042502.
[3] Hong-Yu Zhu, Jian-Ling Lou, Yan-Lin Ye, et al., Nucl. Sci. Tech., 34 (2023) 159.
[4] H. Y. Ge, J. L. Lou, Y. L. Ye, et al., Nucl. Sci. Tech., Nucl. Instr. Meth. A, submitted.
[5] H. Y Zhu, J. L. Lou, Y. L. Ye, et al., in preparation.
[6] H. Y Zhu, J. L. Lou, Y. L. Ye, et al., Chinese Science Bulletin, accepted.
[7] H. Y Zhu, J. L. Lou, Y. L. Ye, et al., in preparation.

Speaker: Mr Hongyu Zhu (School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China)

Presentation_ID199_Zhu.pptx

13:00 Lunch

Plenary Session: 7

Convener: Paolo Giubellino (INFN Torino)

305 Precision Hadron Structure

Nucleons are the building blocks of atomic nuclei,
and are responsible for more than 99 % of the visible matter in the universe.
Around 50 years after the establishment of Quantum Chromo Dynamics as the quantum field theory describing the strong interaction within the Standard Model of particle physics, the precise way in which the quarks and gluons compose the nucleon and build up its global properties, i.e. its mass, momentum, charge, or spin distributions, as well as give rise to its excitation spectrum are still challenging our understanding. Accurate knowledge about e.g. the proton charge radius is not only essential for understanding how QCD works in the non-perturbative region, but also important for bound state QED calculations of atomic energy levels.
In this talk, I will review the progress achieved in exploring nucleon structure both through hard processes and through measurement of low-energy precision quantities.
It will be shown how the three-dimensional momentum-space imaging and tomography of the proton, as well as of nucleon resonances, is connected to low-energy structure quantities such as charge radii and polarizabilities which are crucial inputs in the interpretation of precision atomic spectroscopy experiments.

Speaker: Marc Vanderhaeghen (University Mainz)

INPC2025_vanderhaeghen.pdf

306 Hyperons in nuclei and neutron stars

Recent results and perspectives on hypernuclear physics are summarized based on experimental data at J-PARC and other facilities, and their connection to high-density matter in neutrons stars is also discussed.
Precise investigation of few-body $\Lambda$ hypernuclei ($^3_\Lambda$H, $^4_\Lambda$H, and $^4_\Lambda$He) is of vital importance in determining the hyperon-nucleon interaction. There have been serious puzzles in those light hypernuclei, the hypertriton puzzle (the inconsistency between the measured lifetime and binding energy of $^3_\Lambda$H) and the charge symmetry breaking problem (the observed large difference between $^4_\Lambda$H and $^4_\Lambda$He level energies). The present status of studies at J-PARC, MAMI, ALICE and STAR are reviewed.

As for doubly-strange nuclear systems, recent results of a ($K^-,K^+$) reaction experiment indicate existence of $^{12}_\Xi$Be bound states, and an updated experiment (J-PARC E70) is currently investigating details of those states. The status of recent $\Xi$ atomic X-ray measurements and an H-dibaryon search experiment are also shown.

In order to solve the so-called “hyperon puzzle”, high-quality hyperon-nucleon scattering data are also essential because the precisely determined baryon-baryon interactions in the free space are necessary to extract information on density-dependent baryon-baryon interactions in nuclear matter through hypernuclear data. After the successful $\Sigma$-proton scattering experiment at J-PARC, a new experiment on $\Lambda$-proton scattering has started at SPring-8. On the other hand, precise measurements of medium and heavy $\Lambda$ hypernuclear binding energies are planned at JLab and then at the extended Hadron Facility at J-PARC. Those efforts will determine the strength of the $\Lambda$$N$$N$ three-body repulsive force and clarify whether hyperons exist in neutron stars or not.

Speaker: Hirokazu Tamura (Tohoku University)

Tamura_INPC2025_2.pdf

307 Multi-modal Sensing for Radiation Detection and Imaging

Multi-modal sensing is enabling new and improved capabilities for the detection and imaging of nuclear radiation in real world environments. This presentation will describe how combining radiation detection systems with contextual sensors such as video, Lidar, and GPS/INS allows the realization of transformational technologies for nuclear safety and security. The integration of multi-modal sensing systems with advanced robotic platforms, and how this is paving the way for autonomous radiation detection, imaging, and mapping in a range of applications will also be discussed.

Speaker: Reynold Cooper (Lawrence Berkeley National Laboratory)

308 Nuclear physics for nuclear medicine

Radionuclides are the key ingredient of all radiopharmaceuticals that are used in diagnostic and therapeutic nuclear medicine procedures. A variety of radionuclides with different nuclear and chemical properties is required to cover all needs. Sometimes those radionuclides with optimum nuclear properties for a given application tend to be more challenging to produce in sufficient quality and quantity. In specific cases, nuclear physics studies are required to better characterize the decays or to develop more suitable production paths.

Speaker: Ulli Köster

16:00 Break

Parallel Session: 6_Applications Based on Nuclear Physics

Convener: Juliana Schell (ISOLDE-CERN, Universität Duisburg-Essen)

309 Introduction of macroscopic radiation simulation code PHITS

Particle and Heavy Ion Transport code System (PHITS) is a Monte Carlo macroscopic radiation simulation code in complex three-dimensional geometries[1]. PHITS is a unified program which is intended to treat transport of various particles such as photons, electrons, neutrons, protons, and heavy ions, in wide energy range. PHITS has been used in a variety of practices such as shielding designing of the accelerator facilities, dose evaluation for radiation treatment planning and radiation protection, radiation dosimetry study in space and geoscience, and so on. PHITS contains many different theoretical models and data libraries to simulate necessary calculations in transport process such as stopping power calculation, elastic and inelastic scatterings, nuclear reactions, statistical decays, and so on. The models and data libraries are switched according to the transporting particle, its energy and the medium. PHITS is a tool to connect microscopic nuclear models or nuclear data libraries with macroscopic radiation transport simulations.

We will present how PHITS compute the transport process using those models and data libraries. The accuracy of the PHITS simulation depends on the accuracy of the contained models and data libraries. We are always active to incorporate new models and data libraries into PHITS to achieve better description of physical phenomena so any suggestions and cooperation are very welcome.

[1] T. Sato et al., "Recent improvements of the Particle and Heavy Ion Transport code System - PHITS version 3.33", J. Nucl. Sci. Technol. 61, 127-135 (2024)

Speaker: Dr Takuya Furuta (JAEA)

presentation_ID502_Furuta.pptx

310 Single atom counting with highest sensitivy via AMS

Accelerator Mass Spectrometry (AMS) is the most sensitive technique for measuring longer-lived radionuclides in our environment with applications ranging e.g. from archaeology, geology, climate research, biomedical applications to nuclear astrophysics and nuclear physics. I will highlight here three examples where AMS has demonstrated an outstanding performance.
-) When and were are the heavy elements produced in nature? Nuclear astrophysics aims to study these nucleosynthesis processes. Some radionuclides are characteristic products of specific cosmic explosions and their detection gives insight into e.g. recent supernova-activity close to the solar system on times scales of millions of years. Actinides, such as $^{244}$Pu or $^{247}$Cm are products of the enigmatic r-process nucleosynthesis. AMS has recently been successful in identifying spurious traces of these interstellar radionuclides in terrestrial and lunar archives.
-) Man-made actinides and fission products have been spread globally. They mark a characteristic signature that has become an important tool e.g. in environmental science. In particular, isotopic fingerprints are important in nuclear forensics and they allow identifying their source of origin. The anthropogenic Pu signature was discussed as a most promising marker for the Anthropocene. Clearly, the unmatched abundance sensitivity of AMS is a key for many applications utilizing these radionuclides.
-) The abundance of radionuclides is the interplay between production and their radioactive decay. Changes in the environment affect their abundance level. The half-life of a nuclide defines the time window of its applicability. New dedicated AMS systems allow today to generate highly precise data that is important for dating million-year old archives and that is required for understanding the variations of radionuclide concentrations as a consequence of changing environmental conditions.
This presentation will focus on recent major advancements of AMS exemplifying detection sensitivity and background elimination.

Speaker: Mr Anton Wallner (HZDR)

Presentation_ID719_Wallner.pptx

311 202gPb Production Cross Section Measurements via In-Beam Spectroscopy

To address the lack of accurate data for $^{202g}$Pb production, the Tri-Lab Effort in Nuclear Data (TREND) undertook an effort to measure the cross section values for the proposed $^{nat}$Tl(p,x)$^{202g}$Pb reaction pathway. Prompt in-beam gamma and neutron spectroscopy were performed at the LBNL 88-Inch Cyclotron as an extension to the TREND collaboration’s recent stacked-target measurement of high-energy proton-induced reactions on thallium.

$^{202g}$Pb has been used for geochronology via thermal ionization mass spectroscopy techniques and has been proposed as a reference material for accelerator mass spectroscopy [1, 2]. The isotope is also a candidate for neutrino mass determination due to its favorable low Q-value EC decay (ε:100%, Q=50(15) keV) [3, 4]. The $^{nat}$Tl(p,x) reaction has been proposed as a method of production of this isotope to meet anticipated needs. However, the long lifetime (t$_{1/2}=52.5(28)\times 10^3$ y) and absence of measurable decay gamma rays following electron capture make it difficult to assay the production rate of this isotope with typical foil activation measurements [4]. Conventional in-beam spectroscopy techniques adopted in this experiment allow for direct observation of feeding into the various states of the $^{202}$Pb nuclide, where the prompt gammas serve as the fingerprints of transitions between the energy levels of each band.

Two natural thallium foils, prepared by the Stable Isotope Materials and Chemistry Group at Oak Ridge National Laboratory [5], were irradiated at 30 MeV and 50 MeV incident proton energy respectively at the LBNL 88-Inch Cyclotron [6]. Gamma emission was simultaneously measured by a CLOVER detector (with BGO Compton suppression) and an ORTEC GEM Series detector; throughout the experiment, the CLOVER detector was positioned at various discrete angles (30°–110°) to allow for observations of angular-dependent properties of the pre-equilibrium emissions. Neutron emission at various angles was measured by an array of Eljen EJ-309 liquid scintillators.

The partial cross section values of the $^{nat}$Tl(p,x) reactions extracted from this measurement will be complemented by the TREND effort’s parallel $^{nat}$Tl(p,x) cross section measurements performed via stacked-target irradiations, providing new insights into the direct production of $^{202g}$Pb. An assessment of the production rate and purity of $^{202g}$Pb produced via this pathway can therefore be achieved. The results will be interpreted via comparison with computed predictions made by the reaction-modeling code TALYS. Building on past efforts of the TREND collaboration, the measured angular- and energy- differential cross sections of this work will further our capabilities in seeking optimized parameter adjustments in TALYS, leading to improved predictive capabilities for production of emerging medical radionuclides [7, 8, 9, 10].

This measurement not only produces previously unavailable cross section data for the $^{nat}$Tl(p,x)$^{202g}$Pb reactions, but also expands our capability in probing reactions currently inaccessible via post-irradiation spectroscopy. The production of other high-priority stable and quasi-stable nuclides, and those without quantifiable decay radiation, can be assayed by the techniques developed for this work. The increase in measured data via in-beam spectroscopy will strengthen the predictive power in reaction-modeling codes, benefiting yield predictions of other relevant isotopes produced via proton bombardment at similar energy ranges.

This work was supported by the U.S. Department of Energy Isotope Program, managed by the Office of Science for Isotope R&D and Production, and was carried out by Lawrence Berkeley National Laboratory (Contract No. DE-AC02-05CH11231).

$\bf{References}$

1. A. Wallner et al., “High-sensitivity isobar-free AMS measurements and reference materials for $^{55}$Fe, $^{68}$Ge and $^{202g}$Pb,” Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, vol. 294, p. 374, 2013. Proceedings of the Twelfth International Conference on Accelerator Mass Spectrometry, Wellington, New Zealand, 20-25 March 2011.
2. Y. Amelin and W. J. Davis, “Isotopic analysis of lead in sub-nanogram quantities by TIMS using a $^{202}$Pb-$^{205}$Pb spike,” Journal of Analytical Atomic Spectrometry, vol. 21, p.1053, 2006.
3. A. Welker et al., “Precision electron-capture energy in $^{202}$Pb and its relevance for neutrino mass determination,” The European Physical Journal A, vol. 53, p.153, 2017.
4. S. Zhu and F. G. Kondev, “Nuclear data sheets for A=202,” Nuclear Data Sheets, vol. 109, p. 699, 2008.
5. J. Conner et al., “Development of low-loss minimal exposure technique for thallium foil fabrication,” EPJ Web of Conferences, vol. 285, p. 03003, 2023.
6. M. K. Covo et al., “88-Inch Cyclotron: The one-stop facility for electronics radiation testing,” 2017 IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace), Padua, Italy, 2017.
7. M. B. Fox et al., “Measurement and modeling of proton-induced reactions on arsenic from 35 to 200 MeV,” Physical Review C, vol. 104, p. 064615, Dec 2021.
8. M. B. Fox et al., “Investigating high-energy proton-induced reactions on spherical nuclei: Implications for the preequilibrium exciton model,” Physical Review C, vol. 103, p. 034601, Mar 2021.
9. J. Morrell et al., “Measurement of Proton-Induced Reactions on Lanthanum from 55—200 MeV by Stacked-Foil Activation,” arXiv:2402.17893 [nucl-ex], 2024.
10. C. E. Apgar et al., “Investigation of the Production of $^{117m}$Sn and $^{119m}$Te via Proton Bombardment on Natural Antimony: Implications for Charged Particle Reaction Modeling,” In preparation, 2024.

Speaker: Yun-Hsuan "Abby" Lee (University of California, Berkeley)

Presentation_ID82_Lee.pdf

312 Radioisotopes for monitoring the effects of Climate Change on marine Ecosystems: the REMO/ClimOcean project at SPES/LNL RIB facility

Radioisotopes for monitoring the effects of Climate Change on marine Ecosystems: the REMO/ClimOcean project at SPES/LNL RIB facility

G.de Angelis$^1$, M.D. Marin$^2$, E. Nácher$^3$, B. Rubio$^3$, J. Balibrea-Correa$^3$, T. Cámara$^3$, A. Capasso$^2$, E. Capilla$^3$, I. Daniello$^2$, V. Delgado$^3$, D. García-Párraga$^4$, J. Lerendegui-Marco$^3$, M. Martínez-Roig$^3$, V. Matozzo$^2$, G. Montagnoli$^2$, M. Munari$^2$, M. Roche$^4$, S. Rocca$^1$, L. Sánchez-Blázquez$^3$, C. Tomás$^4$, J. Valiente-Dobon$^1$
$^1$ LNL-INFN, Legnaro, Italy
$^2$ University of Padova and Hydro-biological station, Padova, Italy
$^3$ Instituto de Física Corpuscular (IFIC) CSIC-U. Valencia, Spain
$^4$ Fundación Oceanogràfic, Valencia, Spain

Since the beginning of the industrial revolution, oceans have absorbed about one-third of the carbon dioxide (CO2) released by human activities [1]. This release results in ocean acidification, often referred to as "the other CO2 problem", along with global warming [2]. Ocean acidification is a change in the pH of seawater; CO2 reacts with water molecules (H2O) and forms the weak acid H2CO3 (carbonic acid). It is estimated that if CO2 continues to be released at the same rate as it is today, the acidity of the ocean will increase by 170% compared to pre-industrial levels. Changes are happening at least 10 times faster than at any time in the geological past. A precise knowledge of the influence of the acidity of the waters on the rates of primary production, growth and calcification of some marine species is essential for the risk assessment of coastal ecosystems, the management of the stock of commercial species and to understand the responses of organisms to changes in pH. Considering growth and the blue economy as key issues, acidification also has the potential to affect food security and ecosystem integrity [3]. As coral and bivalve molluscs build their exoskeletons and shells respectively through the production of calcium carbonate (CaCO3), the influence of seawater acidification on the calcium uptake of these organisms can be studied using calcium radiotracers (41,45Ca) in projected acidity conditions [4,5]. The REMO/ClimOcean (Radiotrazadores para el estudio de Ecosistemas Marinos y Oceánicos (Spain)/CLIMate change and OCEAN acidification (Italy)) project focuses on the study of marine species heavily impacted by acidification. The aim is monitoring, non-destructively, the calcium uptake, and therefore the growth, in various corals and bivalve species. In this way, the same individual and the entire colony can be evaluated at any stage of the life-cycle. The non-destructive techniques, without impacting on the animal, represent a technological challenge from the nuclear experimental standpoint. This cross-disciplinary project is possible due to the joint efforts of biologists and nuclear physicists, combining expertise from the Valencia Oceanogràfìc (E), the Hydro-biological station of the University of Padova (I), the Instituto de Física Corpuscular (E) and the INFN-Legnaro National Laboratories (I). The status of the project and the results of the first measurements performed at the Oceanogràfic and Hydro-biological station will be presented, together with the programs for production of novel radiotracers at the SPES facility of the Legnaro National Laboratories (I).

This study is part of the PRIN 20229J3XN CUP 153D23005750001 PE2 and ThinkInAzul supported by MIUR (I) and MCIN (E) with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Generalitat Valenciana project GVATHINKINAZUL/2021/036.
[1] https://gml.noaa.gov/ccgg/
[2] L. Quéré et al., “Global carbon budget 2018”, Earth System Science Data 10, 2141–2194 (2018).
[3] M. Gómez Batista et al., “Intercomparison of four methods to estimate coral calcification under various environmental conditions”, Biogeosciences 17, 887–899 (2020).
[4] T. Cresswell et al., “Exploring New Frontiers in Marine Radioisotope Tracing – Adapting to New Opportunities and Challenges”, Frontiers in Marine Science 7, 10.3389/fmars.2020.00406 (2020).
[5] IAEA, “Nuclear and isotopic techniques help assess ocean acidification and climate change impacts”, IAEA Office of Public Information and Communication 7 (2017).

Speaker: Giacomo de Angelis (INFN Laboratori Nazionali di Legnaro)

04_최종_Giacomo_deAngelis_INPC2025_REMOClimOcean.pptx

313 Medical radioisotope production using laser-driven accelerators

In recent years, there has been a growing interest in laser-driven ion accelerators as a potential alternative to conventional accelerators [1]. A particularly promising application is the production of radionuclides relevant for medical diagnosis, such as 11C for PET imaging. Typically, the production of these nuclides is centralised at cyclotrons, reducing the number of facilities required, but limiting the range of usable radionuclides to those with longer lifetimes [2]. In this context, compact laser-driven accelerators appear as an appealing option for the in-situ generation of short-lived isotopes. Albeit the activities required for PET imaging (>MBq) are well above those achievable from a single laser irradiation (~kBq), the advent of high-power, high-repetition-rate laser systems opens the path to demonstrating relevant activities through the continuous irradiation, provided a suitable target system is developed. A target assembly based on a rotating wheel and automatic alignment procedure for laser-driven proton acceleration at multi-Hertz rates has been developed and commissioned [3]. The assembly, capable of hosting >5000 targets and ensuring continuous replenishment of the target with micron-level precision, has been demonstrated to achieve stable and continuous MeV proton acceleration at rates of up to 10 Hz using our inhouse 45 TW laser system [3].

The continuous production of 11C via proton-induced reactions [11B(p,n)11C] has been recently demonstrated from our target assembly using the 1 Hz, 1 PW VEGA-3 system (CLPU, Spain) [4]. In an initial campaign, an activity of ~12 kBq/shot was measured, with a peak activity of 234 kBq achieved through accumulation of 20 consecutive shots [4]. Furthermore, results of a more recent campaign will be presented, where activation levels in excess of 4 MBq where achieved, as measured through using coincidence detectors, and supported by online measurements of high flux neutron generation. We demonstrate that the degradation of the laser-driven ion beam due to heating of optics is currently the only bottleneck preventing the production of preclinical (~10 MBq) PET activities with current laser systems. The scalability to next-generation laser systems will be explored to study the potential for production of clinical (~200 MBq) activities.

[1] A. Macchi et al., Rev. Mod. Phys. 85, 751 (2013)
[2] S. Fritzler et al., Appl. Phys. Lett. 83, 3039 (2003)
[3] J. Peñas et al., HPLSE 12 (2024)
[4] J. Peñas et al., Scientific Reports 14.1 (2024)

Speaker: Jose Benlliure (Instituto de Física Corpuscular (CSIC - Universitat de Vaència))

Presentation_ID607_Benlliure.pptx

Parallel Session: 6_Hadrons in Nuclei

Convener: Atsushi Hosaka (RCNP, The University of Osaka)

314 In-medium mass shift of two-flavored heavy mesons, $B_c$, $B^*_c$, $B_s$, $B^*_s$, $D_s$ and $D^*_s$

Contributors: G. N. Zeminiani, S. L. P. G. Beres, and $\underline{\bf K. Tsushima}$ (presenter)

The presentation will be based on the recently published article $\bf [1]$ below.

For the first time, we estimate the in-medium mass shift of the
two-flavored heavy mesons $B_c, B_c^*, B_s, B_s^*, D_s$ and $D_s^*$ in symmetric nuclear matter. The estimates are made by evaluating the lowest order one-loop self-energies.
The enhanced excitations of intermediate state heavy-light mesons in symmetric nuclear matter are the origin of their negative mass shift.This negative mass shift may be regarded as a signature of partial restoration of chiral symmetry in an empirical sense, because the origin of the negative mass shift in the study is not directly related to the chiral symmetry mechanism.
Our results show that the magnitude of the mass shift for the $B_c$ meson ($\bar{b} c$ or $b \bar{c}$) is larger than those of the $\eta_c (\bar{c} c)$ and $\eta_b (\bar{b} b)$, different from a naive expectation that it would be in between of them. While, that of the $B_c^*$ shows the in-between of the $J/\psi$ and $\Upsilon$.
We observe that the lighter vector meson excitation
in each meson self-energy gives a dominant contribution for the corresponding meson mass shift, $B_c, B_s,$ and $D_s$.

$\bf [1]$ G. N. Zeminiani, S. L. P. G. Beres and K. Tsushima,
``In-medium mass shift of two-flavored heavy mesons, Bc, Bc, Bs, Bs, Ds, and Ds*,''
Phys. Rev. D 110, no.9, 094045 (2024),
doi:10.1103/PhysRevD.110.094045,[arXiv:2401.00250 [hep-ph]].

Speaker: Prof. Kazuo Tsushima (UNICID - University of City of Sao Paulo)

Presentation_287_Tsushima.pdf

315 In-medium spectral change of vector mesons explored via dielectron decay at J-PARC

J-PARC E16 experiment aims to measure the spectral change of vector
mesons in a nuclear medium. It measures dielectron invariant mass spectra in p+A collisions at 30 GeV. The invariant mass is a mixture of the mass of vector mesons that decay inside and outside of the nuclear medium. Therefore, it is sensitive to the in-medium mass of vector mesons. We give emphasis on phi meson due to its narrow and isolated peak. According to QCD sum rule calculations, the mass is sensitive to the strange quark condensate in the medium.
We have conducted several commissioning runs while increasing the
acceptance, upgrading detectors and DAQ. The last one accepted 206 hours of primary proton beam in total, intermittently conducted in April-June 2024.
We were able to demonstrate excellent electron identification capability
using Hadron Blind Detector (HBD) and Leadglass (LG) calorimeters,
together with four layers of tracking devices, one layer of silicon
detectors (SSD) and three layers of Gas Electron Multiplier (GEM)
Trackers. Omega and phi mesons were observed. In this talk, we report
the outcomes of the commissioning runs and the prospects for the physics run.

Speaker: Kazuya Aoki (KEK)

Presentation_ID584_Aoki.pptx

316 Measurement of Hyper-Hydrogen Lambda-Binding Energy via Decay Pion Spectroscopy

The hypertriton ($^3_\Lambda$Η) is the lightest Lambda-hypernucleus, consisting of one proton, a neutron, and a Lambda. This simplest Lambda hypernucleus has been an essential benchmark for hypernuclear physics. However, the primary properties, mass and lifetime, still have systematic experimental uncertainties. The Lambda-binding energy ($B_\Lambda$) is reported to be $130\pm50$ keV based on emulsion data summarized by Jurič $et$ $al$.[1]. The shallow binding energy suggests a hypertriton lifetime similar to a free Lambda particle ($\tau_\Lambda = 263$ ps)[2]. The recent heavy ion collision experiments have generated considerable interest. After 2010, the STAR and ALICE collaborations have reported a $20-30$% shorter lifetime than $\tau_\Lambda$[3,4]. Furthermore, there are still significant discrepancies in the $B_\Lambda$ values reported by these two groups, differing by a factor of four[5,6]. Accurate and independent measurement of these values is crucial for understanding the hypertriton’s lifetime and mass simultaneously, making this one of the hot topics in hypernuclear physics the ‘Hypertriton puzzle.’
In October 2022, we conducted decay pion spectroscopy experiments on s-shell hypernuclei at the Mainz Microtron MAMI in Germany. The method was established, and the mass of $^4_\Lambda$H was successfully measured with an accuracy of approximately 80 keV in 2016[7].
To enhance the yield of hypertriton and reduce background events, we selected a 4.5 cm long and 0.75 mm wide Lithium target aligned along the beam direction to increase luminosity[8]. Additionally, a new beam energy measurement technique[9] was introduced to reduce the systematic error of hypernuclear mass to $10-20$ keV.
In this session, I will present this experimental method and provide a new result from the latest analysis.

[1] M. Jurič et al, Nucl. Phys. B 52, 1 (1973) 1-30.
[2] H. Kamada et al., PRC 57, 4 (1998)
[3] STAR collaboration, Science 328 (2010) 58
[4] J. Adam et al., Phys.Lett. B 754 (2016) 360-372
[5] S. Acharya et al., PRL 131(2023), 102302
[6] STAR collaboration, Nature Phys. 16 (2020) 4, 409-412
[7] F. Shultz et al., NPA 954, 149 (2016)
[8] P. Eckert et al., EPJ Web Conf. 271, 01006 (2022)
[9] P. Klag et al., NIM A 910 (2018) 147–156

Speaker: Ryoko Kino (Tohoku University)

Presentation_ID555_Kino.pdf

317 Structures and production of Λ40K and Λ48K hypernuclei calculated within multi-configuration space

High-precision experiments of $p$-shell hypernuclear production have been successfully carried out at the Jefferson Laboratory (JLab), disclosing novel excited states. As one of the next advanced experiments, $_{\Lambda}^{40,48}$K production experiments are being planned. These experiments focus on the interaction between a $\Lambda$ hyperon and nucleons in a neutron-rich environment, and therefore it is interesting to know how the isospin dependence is reflected in the energy spectra and production cross sections.

In order to understand the detailed structure of cross sections producing typical $p$-shell hypernuclei, we have extended a shell-model space in which both positive- and negative-parity nuclear states are coupled with hyperon states. In fact this approach succeeded in explaining new extra subpeaks for the first time as well as the pronounced peaks in a consistent way.

In this presentation, we apply the extended shell-model to the analysis of $_{\Lambda}^{40,48}$K and evaluate DWIA spectra of $(\gamma,K^{+})$ reactions, which correspond to the $(e, e' K^{+})$ reaction experiments planned at JLab. Furthermore, we take into account the $\Lambda N$-$\Sigma N$ mixing effect and discuss how the isospin dependence of the $\Lambda N$-$\Sigma N$ mixing affects the hypernuclear energy spectra and production cross sections.

Speaker: Prof. Atsushi Umeya (Nippon Institute of Technology)

Presentation_ID179_Umeya.pdf

Parallel Session: 6_Neutrinos and Nuclei

Convener: SeungCheon Kim (CUP, IBS)

318 Status of DANSS experiment

The DANSS experiment at Kalininskaya NPP is running for already 8 years since
April 2016. The largest in the world in the single experiment statistics of 9 million
inverse beta decay events is collected. The data sample covers 4 full
cycles of the industrial power recator. DANSS experimental program includes both
a search for physics beyond the Standard Model, like sterile neutrinos or large extra
dimensions, and applied studies connected to reactor monitoring using electron
antineutrino flux. The model independent exclusion area in the sterile neutrino parameter
space for 3+1 hypothesis extends till sin$^2$2θ = 0.004 for Δm$^2$ = 0.9 eV$^2$,
where sensitivity of the experiment is the best. Our data show presence of antineutrinos
with energies above 10 MeV in the reactor spectrum with significance of 6.8 σ.
Along with ongoing statistics collection DANSS is preparing for an upgrade, which
shall significantly improve its energy resolution and also increase the fiducial volume.
The talk covers recent analysis results and the upgrade status.

Speaker: Mark Shirchenko (Joint Institute for Nuclear Research)

Shirchenko_INPC25.pptx

319 Precise measurement of $^3$H beta decay spectrum and keV-scale sterile neutrino search

We report analysis results on a LiF Experiment for keV Sterile Neutrino Search (LiFE-SNS) based on tritium beta decay measurement at mK temperatures. We use LiF crystals with $^3$H embedded through the Li(n,$\alpha$)$^3$H process. Magnetic microcalorimeters, one of the high-resolution detector technologies, are adopted to measure the amount of the energy deposited into the crystal absorber from $^3$H beta decays.
A full spectral measurement was conducted using two detector modules, each activated with $^3$H at approximately 30 Bq, over a four-month data taking period. In this conference, we present analysis results, including a comparison of the measured spectrum with the expected $^3$H spectral shape and the results of the search for keV-scale sterile neutrinos.

Speaker: Yong-Hamb Kim

yhkim_inpc2005.pdf

320 Latest Results from the BeEST Phase-III

The Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) experiment searches for the signature of sub-MeV heavy neutrino mass eigenstates in the decay of $^7$Be by precisely measuring the nuclear recoil energy of the $^7$Li daughter nucleus using superconducting tunnel junction (STJ) cryogenic sensors. In Phase-III of the experiment, we utillized a 36-pixel array of the STJ sensors with $^7$Be implantation ranging from 10 to 50 Bq. In this talk, we describe the refined experimental and analytical techniques developed for Phase-III and present the latest results achieved in the Phase-III of the BeEST experiment.

The BeEST experiment is supported, in part, by the DOE-SC Office of Nuclear Physics, the Gordon and Betty Moore Foundation, and the European Metrology Programme for Innovation and Research (EMPIR). TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52- 07NA27344.

Speaker: Inwook Kim (Lawrence Livermore National Laboratory)

Presentation_ID170_Kim.pdf

Parallel Session: 6_New Facilities and Instrumentation

Convener: Yoomin Oh (Center for Underground Physics, Institute for Basic Science)

321 Detection Systems and Research Opportunities at KoBRA

The Korea Broad acceptance Recoil spectrometer and Apparatus (KoBRA) was recently established at the Institute for Rare Isotope Science (IRIS) and successfully commissioned in 2024 using a $^{40}$Ar$^{8+}$ and $^{25}$Na beams. This work provides an overview of the beamline detectors installed in KoBRA and highlights their performance during the commissioning process. It also describes the data acquisition (DAQ) methods employed for processing detector signals, which include conventional approaches using Analog-to-Digital Converters (ADC) and Time-to-Digital Converters (TDC), alongside state-of-the-art digitizers offering 14-bit resolution and a 500 MS/s sampling rate.
In addition, strategies for integrating data to support researchers conducting experiments at KoBRA are discussed, together with plans to apply deep learning algorithms and Monte Carlo simulations for analyzing HPGe detector waveform signals. The application of CdZnTe room-temperature semiconductor detectors (RTSD) for gamma-ray spectroscopy is also under exploration. With their pixelated structure and 3D calibration techniques enabling good energy and 3D interaction position resolution, CdZnTe detectors are well-suited for precise gamma-ray measurements and imaging. Integrating these detectors into KoBRA’s detection system is expected to enhance its functionality and expand opportunities for a wider range of nuclear physics experiments.

Speaker: Dr Kwang-Bok Lee (IBS/IRIS)

322 Development of the prototype AT-TPCs and Sejong TPC-Drum for LAMPS experiment at RAON

We present the development and performance evaluation of two Active-Target Time Projection Chambers (AT-TPCs): a cylindrical-shaped model (TPC-Drum) and a parallelepiped-shaped prototype. These serve as stepping stones for the AT-TPC intended for the low-energy Large Acceptance Multi-Purpose Spectrometer (LAMPS) experiment at RAON. The primary objectives of the TPC-Drum include testing the performance of approximately 1000 readout channels in a magnetic field and investigating alpha clustering structure in rare isotopes and excited alpha-conjugate nuclei, such as C-12 and O-16. Performance tests of the prototype AT-TPCs were conducted using a 200 MeV/u carbon beam at the Heavy Ion Medical Accelerator in Chiba (HIMAC). The results provide valuable insights for the development and optimization of the large scale AT-TPC for low energy experiments.

Speaker: Seonggeun Hwang (Sejong University)

Presentation_ID411_Hwang.pdf

323 HISTARS: A High-Performance Detector for Nuclear Excited-State Lifetimes at HIE-ISOLDE

The ISOLDE facility at CERN is one of the most versatile and prolific facilities worldwide for the production of exotic isotopes using the Isotope Separation On-Line (ISOL) method. The HIE-ISOLDE project has realized a cutting-edge superconducting post-accelerator capable of delivering radioactive ion beams with energies up to 10 MeV/u, making ISOLDE an unique facility worldwide to accelerate medium and heavy isotopes within this energy range.

In order to exploit the vast possibilities offered for research in nuclear structure, nuclear astrophysics and other fields, the HISTARS project aims at building a detection device for the measurement of lifetimes of excited states populated in reactions. Nuclear excite-states lifetimes are essential have direct access to electromagnetic transition rates, which are sensitive to the details of nuclear wavefunctions.

HISTARS combines a charged particle inner detector system with enhanced capabilities for reaction tagging with excellent timing response and an external gamma fast-timing array based on LaBr$_3$(Ce) detectors. The system aims to benefit from recent advancements in instrumentation and electronics, utilizing improvements in digital signal processing and innovative analysis techniques based on genetic algorithms. The project will expand research opportunities for the large community of accelerated beam users at ISOLDE

The presentation will address the HISTARS conceptual design, the technical design study including Monte Carlo simulations, and the performance evaluation of fast-scintillator systems for gamma-rays and charged particles. Test physics cases to showcase the potential of the instrument will be also introduced.

Speaker: Luis Mario Fraile (Universidad Complutense de Madrid)

fraile_INPC2025_HISTARS_270524r.pdf

Parallel Session: 6_Nuclear Astrophysics

Convener: Kyungyuk Chae (Sungkyunkwan University)

324 Towards a new direct measurement of the 12C+12C process deep underground by LUNA

The $^{12}$C + $^{12}$C fusion reaction is pivotal in the synthesis of elements in stars, yet its cross-section at low energies remains poorly constrained, particularly below 2.2 MeV in the center of mass, which is of prime importance for astrophysics. To address this gap, the LUNA collaboration is conducting a direct measurement of this reaction deep underground at the Bellotti Ion Beam Facility (IBF), located at the Italian National Laboratory of Gran Sasso (LNGS). The low-background environment of LNGS, shielded from cosmic radiation by over 1400 meters of rock, offers an ideal setting to investigate rare nuclear reactions with unprecedented sensitivity. This study focuses on the detection of photons emitted in the de-excitation of $^{20}$Ne and $^{23}$Na populated via the two key reaction channels: $^{12}$C($^{12}$C,$\alpha$)$^{20}$Ne and $^{12}$C($^{12}$C,p)$^{23}$Na.
In this presentation, we discuss the preliminary results obtained from recent measurements, including the characterization of various carbon targets under irradiation with the intense $^{12}$C beam from the Bellotti IBF, the experimental setup and the analysis techniques.
These advancements position the LUNA experiment to make the first-ever direct measurement of the $^{12}$C + $^{12}$C reaction in the crucial low-energy regime below 2.2 MeV, with a potential to provide key insights into stellar fusion processes and the origin of elements.

Speaker: Federico Ferraro (INFN - LNGS)

Federico Ferraro - INPC2025.pptx

325 17O burning rate in star: a revision

When stars approach the red giant branch, a deep convective envelope develops and the products of the CNO cycle appear at the stellar surface. In particular, the 17O is enhanced in RGB and AGB stars. Then, spectroscopic analyses of O isotopic ratios of these stars provide a powerful tool to investigate the efficiency of deep mixing processes, such as those powered by convective overshoot, rotation, thermohaline instability, gravity wave and magnetic field. However, this method requires a precise knowledge of the reaction rates that determine the 17O abundance in a H-burning shell, among which the 17O(p, γ)18F and the 17O(p,α)14N reactions are the more relevant. Since the last release of rates compilations (see the JINA reaclib database) a number of experiments have updated the reaction rates, incorporating new low-energy cross section measurements. To provide up-to-date input to the astrophysics community, we performed simultaneous multi-channel and Monte Carlo R−matrix analyses of the two reactions including all newly available data, resulting in realistic uncertainty ranges for the rates.

Speaker: carlo gustavino (INFN)

David-CG-INPC.pdf

326 Impacts of molecular resonances on astronuclear reactions

Various low-energy nuclear reactions play an important role in astrophysical phenomena. In low-energy nuclear reactions, the contribution of resonance states is significant. We discuss the impacts of molecular resonances on ${}^{12}$C+${}^{12}$C fusion and other reactions.
The ${}^{12}$C+${}^{12}$C fusion reaction is a key in the evolution of massive stars and X-ray superbursts. However, due to the thick Coulomb barrier, the reaction has tiny cross sections, making detailed direct measurement experiments difficult. Theoretical studies are also challenging due to the need to deal with the channel coupling between the entrance channel ${}^{12}$C+${}^{12}$C and the exit channels $\alpha + {}^{24}\mathrm{Mg}$ and $p + {}^{27}\mathrm{Al}$.
We estimate the ${}^{12}$C+${}^{12}$C fusion reaction rate treating the channel coupling in the microscopic model: fragments of the ${}^{12}$C+${}^{12}$C molecular resonance caused by the channel coupling with $\alpha + {}^{24}\mathrm{Mg}$ or $p + {}^{27}\mathrm{Al}$ increases the fusion reaction rate. Finite range interactions yield lower energy resonance states by the stronger attraction between ${}^{12}$C's, increasing the reaction rate at low temperatures. We also discuss the possibility of inelastic scattering to populate resonance states that are important for fusion reactions.

Speaker: Yasutaka TANIGUCHI (Fukuyama University)

Presentation_ID376_Taniguchi.pptx

Parallel Session: 6_Nuclear Reactions (1)

Convener: Joochun (Jason) Park (CENS, IBS)

327 Exploring new features in rare isotopes through direct reactions

The rare isotopes have ushered a new era in nuclear science unveiling structural features that challenge conventional knowledge. The emergence of exotic features like the neutron halo and neutron skin in neutron-rich nuclei are tied to mutations of the nuclear shell closures that are well established from our knowledge of stable nuclei. This raises questions on our complete understanding of the strong nuclear force of nature that binds visible matter. The properties of these exotic nuclei guide our understanding on the state of matter in extreme neutron-rich systems in our Universe. The reactions and decays of these isotopes drive the creation of majority of the heavy elements in our Universe .

The presentation will outline how reactions with rare isotope beams at different energy scales are allowing us to unveil unexpected new features in rare isotopes. This is leading to revelation of unconventional forms of nuclei such as nuclear halo and skin, their exotic excitation phenomena, and fundamental changes of nuclear shells that break the bounds of our traditional knowledge. The characterization of low-energy excited states in neutron-rich nuclei with nucleon transfer reactions and inelastic scattering using a solid H2/D2 target at TRIUMF will be presented. The exploration of radii around N = 14 – 16 in neutron-rich isotopes at RIKEN-RIBF will be presented showing the appearance of exotic structures and their relation to shell evolution.

Speaker: Prof. Rituparna Kanungo (TRIUMF)

INPC_2025_RKanungo.pdf

328 Determination of prolate or oblate shape via low-energy $\alpha$ inelastic scattering

Understanding nuclear shape is a crucial problem in nuclear physics, significantly impacting our knowledge of nucleon single-particle dynamics and collective nuclear behavior. While the quadrupole deformation parameter $\beta_2$ has been well studied in terms of magnitude, determining its sign $-$whether prolate or oblate$-$ remains a challenging problem because many observables are sensitive only to the square of $\beta_2$. Traditional approaches, such as electric quadrupole moments and Coulomb excitation experiments, provide crucial insight into nuclear deformation including its sign, however, they are often impractical for neutron-rich unstable nuclei. These unstable nuclei are indispensable for understanding shell evolution, emphasizing the importance of properly determining their deformation and its sign.

In this study, we propose a method to determine the sign of nuclear deformation by using low-energy $\alpha$ inelastic scattering [1]. Our approach utilizes the nuclear reorientation effect (RE), which is known as a self-coupling of excited states [2]. Our approach is based on a standard coupled-channel framework within the macroscopic model, enabling us to present how RE modifies cross sections differently for prolate and oblate shapes. We demonstrated the feasibility of this technique with $\alpha$ scattering on a stable target, $^{154}$Sm, at 50 MeV, for which the experimental data are available. Our results show distinct differences in inelastic cross sections for positive and negative $\beta_2$ values, establishing low-energy $\alpha$ inelastic scattering as a promising tool for systematically determining the sign of deformation. In the presentation, we will extend this method to unstable nuclei with the neutron number $N=28$ such as $^{40}$Mg (expected to be prolate) and $^{42}$Si (expected to be oblate), to demonstrate its broader applicability.

[1] S. Watanabe et al., Phys. Rev. C 110, 034618 (2024).
[2] G. R. Satchler, Direct Nuclear Reactions (Clarendon Press, Oxford, 1983).

Speaker: Dr Shin Watanabe (National Institute of Technology (KOSEN), Gifu College)

Presentation_ID#38_Watanabe.pptx

329 Preliminary Results of 12C Neutron Elastic Scattering using CoGNAC at the LANSCE White Neutron Source

Cross section data and associated uncertainty quantification regarding neutron scattering can be lacking or missing especially for stable nuclei found in common materials. This lack of information negatively impacts nuclear studies. Elastic scattering knowledge is particularly limited for many stable isotopes, especially in the MeV incident neutron energy where scattering is the most probable interaction, but experimental measurements become increasingly challenging. A nucleus with sparse elastic scattering data is 12C
despite its prevalence in a multitude of materials that are used in structural, shielding, and detector materials. The Correlated Gamma Neutron Array for sCattering (CoGNAC) experimental program at Los Alamos National Laboratory aims to provide neutron
scattering cross section measurements along with detailed uncertainty and covariance quantification across a range of incident neutron energies. An introduction to CoGNAC and preliminary 12C elastic scattering results from the Los Alamos Neutron Science Center will be discussed and presented.

Funding: NSF PHY-2310078 & NNSA/DOE O[ice of Experimental Science (NA-113)

Speaker: Nicholas Mendez (Michigan State University / Facility for Rare Isotope Beams / Los Alamos National Laboratory)

330 Elastic scattering of 12B + 120Sn reaction

Over the years, elastic scattering measurements involving light radioactive projectile nuclei have gained much interest. One of the main objectives of such measurements is to understand the various reaction mechanisms that play a role in the elastic scattering process. Elastic scattering using boron isotopes as projectiles has been shown to be an intriguing case for investigating several effects that can be present in the process. However, experimental data with boron isotope projectiles are scarce, particularly for the 12B isotope. Angular distributions of the 12B + 120Sn elastic scattering are measured at 48 MeV incident energy. The experiment was performed in the RIBRAS (Radioactive Ion Beams in Brasil) facility at the Nuclear Physics Open Laboratory (LAFN) of the University of Sao Paulo. The 11B primary beam was delivered by the 8-UD Pelletron accelerator with 48 MeV energy impinging in the RIBRAS primary scattering chamber where a 12 μm 9Be foil was used as production target. The secondary 12B radioactive ion beam was produced by the 9Be(11B, 12B) reaction. The obtained angular distributions were analyzed in terms of the large-scale coupled channel (CC) and coupled reaction channel (CRC) calculations, where several inelastic transitions for the target, as well as the most relevant transfer reactions, have been included in the coupling matrix elements. Additionally, these results are compared with previously measured 12B+58Ni at RIBRAS as well as with existing experimental data using the same 120Sn target, such as for 4,6He, 6,7Li, 9,11Be, and 8,10,11B. Preliminary results will be presented.

Speaker: Sunday Olorunfunmi (Instituto de Física da Universidade de São Paulo)

331 Observation of the third 2+ state in 16C via inelastic scattering reactions

Carbon isotopes provide an important platform to examine the shell closure of Z=6, which was suggested to exist in $^{14}$C due to the spin-orbital splitting of $0p_{1/2}$ and $0p_{3/2}$ [1-3]. However, it is not yet clear whether $Z=6$ closure persists in other Carbon isotopes, although there is some evidence in the proton distribution radii [1,4-7]. The first $2^+$ state in $^{16}$C was shown to be dominated by neutron excitation, but its ratio between neutron and proton quadrupole moments ($M_n/M_p$) is still not conclusive, though it has been studied by many experiments[8-13]. Questions remain about whether the second $2^+$ state is dominated by the proton or neutron excitation, and if there is a higher $2^+$ state dominated by proton excitation. In order to answer these questions, we have measured inelastic scattering reactions of the 16C nucleus on proton and deuteron with the active-target time projection chamber (AT-TPC) of Michigan State University [14] coupling to the magnetic field of HELIOS [15]. These two reactions provide two independent probes, protons and neutrons, with that have different sensitivity to protons and neutronsthe excitation of $^{16}$C. Therefore, new $M_n/M_p$ values were determined for the first $2^+$ states. A new $2^+_3$ resonance was observed at 6.1 MeV, which was found to be dominated by proton excitation. These present results seem to support the persistence of the $Z=6$ closure in $^{16}$C.

This research used resources of Argonne National Laboratory’s ATLAS facility, which is a Department of Energy Office of Science User Facility. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear
Physics, under Contracts No. DE-AC02-06CH11357 (ANL), No. DE-FG02-87ER40371(FRIB).

[1] Angeli, István, and Krassimira Petrova Marinova. "Table of experimental nuclear ground state charge radii: An update." Atomic Data and Nuclear Data Tables 99.1 (2013): 69-95.
[2] Nakamura, T., H. Sakurai, and H. Watanabe. "Exotic nuclei explored at in-flight separators." Progress in Particle and Nuclear Physics 97 (2017): 53-122.
[3] Brown, B. Alex. "The nuclear shell model towards the drip lines." Physics 47.2 (2022): 525-547.
[4] Kanungo, R., et al. "Proton Distribution Radii of 12-19C Illuminate Features of Neutron Halos." Physical Review Letters 117.10 (2016): 102501.
[5] Suzuki, Y., et al. "Parameter-free calculation of charge-changing cross sections at high energy." Physical Review C 94.1 (2016): 011602.
[6] Tran, D. T., et al. "Charge-changing cross-section measurements of 12-16C at around 45 A MeV and development of a Glauber model for incident energies 10 A–2100 A MeV." Physical Review C 94.6 (2016): 064604.
[7] Tran, D. T., et al. "Evidence for prevalent Z= 6 magic number in neutron-rich carbon isotopes." Nature communications 9.1 (2018): 1594.
[8] Imai, N., et al. "Anomalously Hindered E2 Strength B (E2;2_1^+→ 0_^+) in 16C." Physical review letters 92.6 (2004): 062501.
[9] Elekes, Z., et al. "Decoupling of valence neutrons from the core in 16C." Physics Letters B 586.1-2 (2004): 34-40.
[10] Ong, H. J., et al. "Neutron-dominant quadrupole collective motion in 16C." Physical Review C—Nuclear Physics 73.2 (2006): 024610.
[11] Ong, H. J., et al. "Lifetime measurements of first excited states in 16,18C." Physical Review C—Nuclear Physics 78.1 (2008): 014308.
[12] Wiedeking, M., et al. "Lifetime Measurement of the First Excited 2+ State in 16C." Physical review letters 100.15 (2008): 152501.
[13] Jiang, Y., et al. "Quadrupole deformation of 16C studied by proton and deuteron inelastic scattering." Physical Review C 101.2 (2020): 024601.
[14] Suzuki, D., et al. "Prototype AT-TPC: Toward a new generation active target time projection chamber for radioactive beam experiments." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 691 (2012): 39-54.
[15] Wuosmaa, A. H., et al. "A solenoidal spectrometer for reactions in inverse kinematics." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 580.3 (2007): 1290-1300.

Speaker: Jie Chen (Southern University of Science and Technology)

Presentation_ID6647_Jie_Chen.pdf

Parallel Session: 6_Nuclear Reactions (2)

Convener: Kimiko Sekiguchi (Kyoto University)

332 Deuteron quasi-free scattering reactions: a tool to probe nucleon-nucleon short-range correlations in atomic nuclei

The experimental evidence points to the existence, at short distances, of strongly correlated neutron-proton pairs much like they are in the deuteron or in free scattering processes. As it moves through the nuclear medium, a “bare” nucleon in the presence of the nucleon-nucleon interaction becomes “dressed” in a quasi-deuteron cloud [1], about 20% of the time. A phenomenological analysis of the quenching of spectroscopic factors [2] and recent data from Jefferson Lab [3] point to an isospin dependence of the independent-particle model content in a dressed nucleon. It is expected that this dependence should also be reflected in the dressed amplitude and thus, in the virtual quasi-deuteron content in the ground state.

Following from the qualitative arguments above, quasi-free scattering (QFS) of deuterons for which the fast reaction time $t_R$ becomes comparable to the time scale of the virtual excitations, $t_R \sim \hbar / \Delta E$, could offer a sensitive probe to examine these concepts.

In this contribution, I will discuss these ideas within a single-j approximation and put forward an experimental case that can serve as a template to test the above conjecture, i.e., measuring the (p,pd) QFS cross section for knocking out a deuteron in $^{10,14,16}$C relative to $^{12}$C as an additional tool to probe short-range correlations and their isospin dependency.

[1] K. Brueckner, in Proceedings of the Rutherford Jubilee Int. Conf. Manchester 1961 (Heywood & Company LTD, London, 1961)

[2] S. Paschalis, M. Petri, A. O. Macchiavelli, O. Hen, and E. Piasetzky, Physics Letters B ${\bf 800}$ (2020) 135110

[3] M. Duer, et al., Nature ${\bf 560}$ (2018) 617

Speaker: Marina Petri (University of York)

Presentation_ID532_Petri.pdf

333 Measurement of ground-state and isomeric-state ratio in nuclei produced in multinucleon transfer reactions using JAEA Recoil Mass Separator

Multinucleon transfer (MNT) reaction is attracting interest in the field of astrophysics and superheavy-element research as the reaction can produce neutron-rich actinide and superheavy nuclei. In contrast to fusion-evaporation residue, however, reaction mechanism such as excitation energy and spin distributions of the primary excited compound nucleus is not understood, which will significantly impact the cross sections of produced evaporation residues (ERs), as it will determine survival probability to produce ERs in competition to fission. We are investigating the MNT reaction by directly detecting ERs using the Recoil Mass Separator (JAEA-RMS[1]) at the JAEA tandem accelerator facility. Since the JAEA-RMS features a rotation mechanism (0~40 degrees) around the beam direction, detailed measurement of ER cross sections as a function of recoil angle is possible. The first experiment was performed with the 30Si+209Bi reaction. The ERs transported through the JAEA-RMS were implanted in a silicon strip detector, and the subsequent alpha decay was measured to identify produced nuclei, as well as ground state and isomeric state. The results became the first demonstration of the in-flight separation and on-line decay measurement at finite angles. We observed remarkable differences in the cross sections between high-spins isomeric state and low-spin ground state(212At(9-)/212At(1-), 214Fr(8-)/214Fr(1-), 211Po(25/2+)/211Po(9/2+)), which should have a memory of spin distribution of compound nucleus.

Reference
[1] H. Ikezoe et al., Nucl.Instrum.Methods Phys.Res.A 376, 420 (1996)

Keywords : Multinucleon transfer reaction, Evaporation residue, Recoil mass　separator, Isomer-to-ground state ratio

Speaker: Fumi Suzaki (Japan Atomic Energy Agency)

Presentation_ID61_Suzaki_upload.pdf

334 Indirect Measurement of 88Y(n,γ) cross-sections by surrogate reaction method

Neutron capture cross-section is a crucial component in understanding the origin of elements, modeling nuclear devices and interpreting nuclear data for security applications. While a large part of the demanded capture cross-sections involves short-lived and highly radioactive targets, direct measurement of neutrons with these targets are extremely difficult or costly.
In this work, a surrogate reaction was proposed for indirectly determining the 88Y(n,γ) cross-sections with p + 89Y system. The selected inelastic scattering proton in coincidence with two characteristic gammas of 89Y are utilized to acquire the probabilities of gamma decay channel. Then, combined with the cross-sections of compound nucleus formation calculated  with optical model, desired 88Y(n,γ) cross-sections are obtained in Weisscopf-Ewing Approximation for the first time. Also, corrections are discussed for the spin-parity differences between original and surrogate reactions.

Speaker: JING FENG (CIAE)

335 A new experiment on the radiative decay of the 12-C Hoyle state with charged‑particle spectroscopy

The Hoyle state in 12C (7.654, 0+) is a famous clustered state whose peculiar properties are key for determining the rate at which carbon, one of the most abundant elements in the Universe, is forged in stars. The competition between alpha- and radiative- decays of this peculiar state crucially affects the relative abundance of carbon and oxygen in the Universe and the mass limits for the formation of black holes. However, a strong tension in the determination of its radiative decay branching ratio characterizes recent experimental works, posing major implications on the aforementioned fundamental aspects of nucleosynthesis and stellar evolution. This talk describes an almost background-free measurement of the radiative decay branching ratio of the Hoyle state that exploits charged particle coincidence techniques. The experiment adopts several methodologies to minimize the background and identify the signal associated with the radiative decay. Large care is devoted to having under full control two of the major sources of systematic errors in particle-coincidence experiments: the coincidence efficiency and the spurious coincidence rate. The new findings help to resolve the strong tension between recent data published in the literature.

Speaker: Luigi Redigolo (University of Catania, Italy / INFN - Sezione di Catania, Italy)

Presentation_ID49_Redigolo.pptx

Parallel Session: 6_Nuclear Structure (1)

Convener: Fang-Qi Chen (Lanzhou University)

336 First Identification of Excited States in $^{78}$Zr and Implications for Isospin Non-Conserving Forces in Nuclei

Isospin symmetry is a fundamental concept arising from the assumed charge symmetry and charge independence of the strong nuclear force. However, a wealth of experimental evidence has revealed isospin non-conserving interactions, which manifest, for example, in the excitation energies of analog states in $T$ = 1 triplet nuclei. Until recently, the triplet energy difference (TED) data were available for $A$ = 42 to $A$ = 74 isobaric triplets, but have now been extended to cover the $A$ = 78, $T$ = 1 triplet, which is currently the heaviest system for which complete TED data exist.
A fusion-evaporation reaction study conducted at the Accelerator Laboratory of the University of Jyvaskyla led to the first observation of the 2$^+$ and, tentatively, the 4$^+$ excited states in the $N$ = $Z$ - 2 nucleus $^{78}$Zr [1]. This study also provided new structural information for the $N$ = $Z$ nucleus $^{78}$Y. These results were obtained using the JUROGAM 3 Ge-array coupled with the vacuum-mode mass separator MARA, along with employing the recoil-$\beta$ and recoil-$\beta$-$\beta$ correlation techniques. This presentation will discuss the new experimental results for the $A$ = 78 triplet, which appear to be inconsistent with those obtained from contemporary theoretical calculations based on both the shell model and density functional theory.

References:
[1] G.L. Zimba, P. Ruotsalainen, D.G. Jenkins, W. Satula et al., Phys. Rev. Lett., Accepted 12 November, 2024

Speaker: Panu Ruotsalainen (University of Jyväskylä)

Presentation_ID576_Ruotsalainen.pdf

337 Lifetime Measurements in N=Z 88Ru at FRIB

Crucial questions remain unanswered in the heaviest accessible region of $N=Z$ nuclei, where both the neutron and proton Fermi levels are located well inside the $g_\frac{9}{2}$ region. The details of how collectivity varies for $N=Z$ nuclei between $^{56}$Ni and $^{100}$Sn, and the location, and extent, of the maximum collectivity presents a demanding test of our best nuclear-structure models - see e.g. [1]. The reduced transition probability $B(E2: 2_1^+\rightarrow 0_1^+$) remains one of the most sensitive probes of quadrupole collectivity and can provide an indication of nuclear deformation. To date the heaviest $N=Z$ systems, for which $B(E2: 2_1^+\rightarrow 0_1^+$) have been measured, are $^{78}$Y (odd-odd) and $^{80}$Zr (even-even) [2]. The results demonstrate the presence of rapidly changing nuclear collectivity with the addition of nucleons beyond mass 70. An issue of much contemporary significance in this region is whether $N=Z$ nuclei are likely to show clear evidence for isoscalar ($T=0, J>0$) np-pairing correlations [3]. A measurement of the $B(E2: 2_1^+\rightarrow 0_1^+$) can potentially shed light on these issues. For example, calculations [4] suggest that $T=0$ np pairing plays an important role in both the evolution of the moments of inertia in the $N=Z$ nucleus $^{88}$Ru and the absolute value of the predicted $B(E2: 2_1^+\rightarrow 0_1^+$). Indeed, the structure of the $^{88}$Ru yrast band exhibits a delayed rotational alignment [5] which has been interpreted in terms of the presence of such isoscalar np pairing. In this contribution, new results from FRIB on the lifetime of the $2^+$ state in $^{88}$Ru will be presented - the heaviest $N=Z$ nucleus for which such a measurement has been possible. We will also report on progress towards the lifetime measurement of the $T=1$ $2^+$ state in odd-odd $N=Z$ $^{86}$Tc.

The experiment was performed in April 2023 at FRIB. A 250 MeV/u $^{124}$Xe beam was used to produce fragmentation beams of $^{88}$Tc and $^{89}$Ru, separated using the new ARIS spectrometer at FRIB. Final fragments were identified using the S800 spectrometer, with $\gamma$ rays recorded using GRETINA. The TRIPLEX plunger device was utilised in order to determine the lifetimes, and hence $B(E2: 2_1^+\rightarrow 0_1^+$) values, for the $N=Z$ nuclei $^{88}$Ru and odd-odd $^{86}$Tc. The first results for the measured $B(E2: 2_1^+\rightarrow 0_1^+$) for $^{88}$Ru will be presented and compared with state-of-the-art shell-model and DFT calculations. For the shell model, two new approaches are available and have been applied to the new results for $^{88}$Ru. The first is the new Discrete Nonorthognal shell-model approach [6], which applies mean-field and beyond-mean-field techniques, and the second is the large-scale shell model (LSSM) using a new interaction, ZBM3 [7], operating in the $f_{5/2},p,g_{9/2},d_{5/2},s_{1/2}$ space. The new results for $^{88}$Ru present the first opportunity for $N=Z$ results to be evaluated in such a model space.

References
[1] K. Kaneko, Y. Sun and T. Mizusaki, Phys. Rev. C 97 (2021) 054326.
[2] R. D. O.Llewellyn, M. A. Bentley, R. Wadsworth et al, Phys. Rev. Lett. 124, (2020) 152501.
[3] S. Frauendorf and A.O. Macchiavelli, Prog. in Part. and Nucl. Phys. 78, (2014) 24.
[4] K. Kaneko et al, Nucl. Phys. A, 957, (2017) 144-153.
[5] B. Cederwall et al., Phys. Rev. Lett. 124, (2020) 062501.
[6] D. Dao and F. Nowacki, Phys. Rev. C 105, (2022) 054314.
[7] J. Ha et al, submitted to Nature Physics (2024)

Speaker: Michael Bentley (University of York)

Presentation_ID109_Bentley.pdf

338 Evidence against shape coexistence and in favour of triaxiality in 70Se

In the selenium isotopes various shape phenomena are present. The scenario of shape coexisting oblate and prolate bands has been proposed across the isotopic chain, with the crossing point of such bands being located near $^{70}$Se.
A combined internal conversion electron and $\gamma$-ray spectroscopy study was undertaken at the TRIUMF-ISAC-II facility to undertake a comprehensive search for evidence of the existence of a $0^+$ state below 2 MeV in $^{70}$Se. Significant discrepancies to the previously established positive parity level scheme were found.
Generalised Bohr Hamiltonian calculations using UNEDF1 mass parameters were found to reproduce the revised low-lying level structure well, with the $2_2^+$ state resembling a quasi-$\gamma$ excitation rather than a member of a shape coexisting band.

Speaker: James Smallcombe (JAEA)

Presentation_ID093_Smallcombe.pdf

339 In-beam spectroscopy of 94Ag

The formal concept of isospin has been introduced to explain the apparent exchange symmetry between neutrons and protons. However, if the nuclear force were the same for protons and neutrons properties such as masses and excitation energies would depend only on the mass number A. Recent studies have shown that the Coulomb force cannot account for all deviations, suggesting that other isospin-symmetry-breaking components must be present. N⁓Z systems present the perfect testing ground to probe isospin symmetry phenomena [1-3]. In addition, pairing correlations have a significant importance in the description of the nuclear structure of N=Z nuclei, where protons and neutrons are arranged occupying the same orbits, allowing T=0 np pairing in addition to the normal T=1. It was recently suggested that spin-aligned T=0 np pairs dominate the wavefunction of the y-rast sequence in 92Pd [4]. Subsequent theoretical studies were devoted to probe the contribution of np pairs in other N=Z A>90 nuclei [5-6], suggesting that a similar pairing scheme strongly influences the structure of these nuclei.

In an effort to answer these questions further, a recoil-beta-tagging experiment has been performed to study the excited T=0 and T=1 states in the odd–odd N = Z nucleus 94Ag, populated via the 40Ca(58Ni,1p3n)94Ag reaction. The experiment was conducted using the MARA recoil separator and JUROGAM3 array at the Accelerator Laboratory of the University of Jyväskylä. Through correlating fast, high-energy beta decays at the MARA focal plane with prompt γ rays emitted at the reaction target, a number of transitions between excited states in 94Ag have been identified for the first time [7].

The detailed goals of the experiment, the setup, the identified transitions and the experimental CED will be shown in this presentation. The results will also be compared with nuclear shell model predictions and a preliminary interpretation will also be discussed.

[1] K. Wimmer, et al., Phys. Rev. Lett. 126, 072501 (2021).
[2] R.D.O. Llewellyn, et al., Phys. Lett. B 797, 135873 (2019).
[3] A. Boso, et al., Phys. Lett. B 797, 134835 (2019).
[4] B. Cederwall, et al., Nature 469, 6871 (2011).
[5] G.J. Fu, et al., Phys. Rev. C 87, 044312 (2013).
[6] Z.X. Xu, et al., Nucl. Phys. A 877 (2012) 51-58.
[7] X. Pereira-Lopez, et al., Eur. Phys. J. A (2023) 59:44.

Speaker: Xesus Pereira-Lopez (Center for Exotic Nuclear Studies (CENS), Institute for Basic Science (IBS))

Presentation_ID14_PereiraLopez.pdf

340 Level lifetime measurement of $^{93}$Ru and $^{94}$Ru by IDATEN: Seniority symmetry breaking

Lifetimes of the low-lying excited states in the yrast bands of $^{93}$Ru and $^{94}$Ru were measured using the $\gamma$-$\gamma$-$\Delta T$ method. The experiment was carried out at the Radioactive Isotope Beam Factory (RIBF) at RIKEN. The $^{93}$Ru and $^{94}$Ru were produced by in-flight fragmentation of a $^{124}$Xe primary beam, impinging on a $^9$Be target. These ions were transported through the BigRIPS and Zero Degree Spectrometer (ZDS) and implanted into a segmented plastic-based active stopper at F11, one of the focal positions. The $\gamma$ rays emitted from the isomeric decays were detected by the IDATEN (International Detector Assembly for fast-Timing measurements of Exotic Nuclei) array, which consists of 48 LaBr3(Ce) detectors.
Recent studies have reported the anomalous enhancement of the reduced transition probabilities for the $4^{+} \to 2^{+}$ transition in $^{94}$Ru, compared to the theoretical prediction based on the large-scale shell model with partial seniority conservation. This enhancement has been attributed to a small mixing of $\nu$ = 4 and 2 seniorities. However, the previous results are inconsistent, and the additional high-precision experimental data are required to better understand the seniority mixing. In this presentation, we report new level lifetime values for $^{93}$Ru and $^{94}$Ru and discuss their implications for the seniority symmetry breaking.

Speaker: Jaehwan Lee (Korea University)

Presentation_ID357_LEE.pptx

341 Seniority nature in 94Pd using fast-timing measurement with IDATEN

We have investigated the seniority feature of $^{94}$Pd with its level lifetime measured by the fast-timing technique. The experiment was carried out at the Radioactive Isotope Beam Factory (RIBF) at RIKEN. $^{94}$Pd was produced by in-flight fragmentation of a $^{124}$Xe primary beam impinging on the $^{9}$Be target. The secondary cocktail beams were identified using the BigRIPS separator and implanted into the segmented plastic active stopper at one of the focal points, F11. The gamma rays emitted from the isomeric decay of $^{94}$Pd were detected by the International Detector Assembly for fast-Timing measurements of Exotic Nuclei (IDATEN) array, consisting of 48 LaBr$_{3}$(Ce) detector modules. The high-statistics data obtained by the Twinpeaks+TAMEX4 DAQ system enables us to determine more precisely the half-life of the first 8+ state in $^{94}$Pd. These results are expected to provide critical insights into the seniority effects in the region adjacent to the doubly magic nucleus $^{100}$Sn.

Speaker: Youngseub Jang (Korea University)

INPC 2025_Youngseub.pdf

342 Seniority in atomic nuclei

Seniority refers to the number of nucleons that are not in pairs coupled to angular momentum J=0. As shown by Racah in the 1940s, it is a symmetry exhibited by the pairing interaction and, more generally, it is a quantum number approximately conserved for a general interaction between either neutrons or protons. In this talk I review the conditions for the conservation of seniority and show that they are a manifestation of particle-hole symmetry.

Many properties of nuclei can be understood with simple arguments based on seniority and some of them will be discussed in this talk. In particular, the symmetry of seniority gives rise to selection rules in the electromagnetic decay in nuclei that may lead to the formation of isomers. Another topic of interest concerns the relation between B(E2) values in even-even and odd-mass nuclei in the shell model as opposed to the predictions of the particle-core coupling model. Finally, the question of (state-dependent) effective E2 charges in the shell model will be addressed.

Speaker: Piet Van Isacker (GANIL)

presentation_id266_Vanisacker.pdf

Parallel Session: 6_Nuclear Structure (2)

Convener: HIROYUKI SAGAWA (RIKEN/University of Aizu)

343 Laser spectroscopy of the Heaviest Elements

The heaviest elements are of interest to nuclear and atomic physicists due to their peculiar properties. While nuclear shell structure effects are responsible for their very existence stabilizing them against spontaneous disintegration, the structure of their electronic shells is affected by strong relativistic effects leading to different atomic and chemical properties compared to their lighter homologs. The atomic structure can be probed by laser spectroscopy. This is a powerful tool to unveil fundamental atomic and, from the determination of subtle changes in atomic transitions, nuclear properties. The lack in atomic information on the heavy element of interest, the low production rates, and the rather short half-lives make experimental investigations challenging and demand very sensitive experimental techniques.
Laser spectroscopy of accelerator produced heavy nobelium (No, Z=102) isotopes in atom-at-a-time quantities became accessible in the pioneering experiment employing the RAdiation Detected Resonance Ionization Spectroscopy (RADRIS) technique at the velocity filter SHIP at GSI, Darmstadt. More recent measurements with additional advancements of the setup and employing a novel mode of the RADRIS technique, where the desired nuclides are bred by radioactive decay on the capture filament, extended the reach of the method to $^{251,255}$No and, for the first time, to on-line produced fermium (Fm, Z=100) isotopes. These on-line experiments are complemented by off-line laser spectroscopy measurements at the RISIKO mass separator at Mainz University on reactor-bred heavy actinides with suitable long lifetimes. Hot-cavity laser spectroscopy on radio-chemically purified samples enabled the investigation of isotopes of the heavy actinides curium (Cm, Z=96), californium (Cf, Z=98), einsteinium (Es, Z=99), and fermium. This experimental endeavor is accompanied by improvements of theoretical atomic calculations enabling the determination of nuclear ground state properties from the extracted atomic observables of isotope shifts and hyperfine structure parameters. This provides insight to the peculiar nuclear nature and especially the deformation of the heaviest elements. The obtained results will be discussed in view of nuclear theory predictions together with the perspectives for laser spectroscopic investigations in even heavier elements.

Speaker: Sebastian Raeder (GSI Helmholtzzentrum für Schwerionenforschung GmbH)

Presentation_ID542_Raeder.pptx

344 Present status and perspective of the SCRIT electron scattering facility

The world's first electron scattering experiment on online-produced radioisotopes (RIs) was successfully conducted at the SCRIT electron scattering facility, located at the RIKEN RI Beam Factory in Japan.
Electron scattering is widely recognized as one of the most powerful and reliable methods for investigating the structure of atomic nuclei due to its well-understood electromagnetic interaction mechanism.

Despite the long-standing ambition to explore exotic features of short-lived unstable nuclei through electron scattering, such studies have been hindered by the challenge of preparing sufficiently thick targets.
However, we have recently achieved a significant breakthrough by successfully performing electron scattering on $^{137}$Cs.
This isotope was produced via the photo-fission of uranium and promptly transferred to the SCRIT system, where it was trapped to make a stationary target in a short timeframe.

This experiment represents a major milestone in simulating electron scattering from short-lived unstable nuclei produced online, paving the way for further advancements, especially with future upgrades to the ISOL driver’s power.
In this presentation, we will highlight the recent progress and future prospects of the SCRIT electron scattering facility.
We will also discuss several potential research topics that could become feasible in the future through the unique capabilities of the SCRIT method.

Speaker: Kyo Tsukada (ICR Kyoto University)

Presentation_ID581_Tsuada.pptx

345 In-gas-jet laser spectroscopy of the heaviest elements

The in-gas-jet laser spectroscopy technique is a powerful tool to study atomic and nuclear properties of short-lived actinides. Such studies are important to understand the atomic level scheme of these heavy elements, which is influenced by strong electron correlations and relativistic effects. Also, fundamental nuclear properties such as moments, spins and charge radii are unknown for most of these nuclei. Thus, experimental data are crucial to benchmark state-of-the-art atomic and nuclear models.

The Radiation Detection Resonance Ionization Spectroscopy (RADRIS) technique, at GSI, Darmstadt, has provided pioneering experimental data for nobelium and fermium isotopes [1, 2, 3]. The RADRIS technique, however, is limited in the attainable spectral resolution mainly owing to collision- and Doppler-broadening. To overcome these limitations the JetRIS setup [4] has been designed to perform laser spectroscopy in a low-density and low-temperature supersonic gas jet [5] produced by a de-laval nozzle [6, 7]. The performance of JetRIS has been tested online with the spectroscopy of 254No, showing a six-fold increase in spectral resolution with respect to the RADRIS technique [8].

In this contribution we will present the research and development work carried out to commission the JetRIS setup as well as its performance in the upcoming online campaign and the prospects.

References:
[1] M. Laatiaoui et al., Nature 538, (2016) 495–498
[2] S. Raeder et al., Phys. Rev. Lett., 120 (2018) 232503
[3] J. Warbinek et al., Nature 634, (2024) 1075
[4] S. Raeder et al., NIMB 463, (2020) 272–276
[5] Yu. Kudryavtsev et al., Nucl. Instrum. Methods Phys. Res. B, 297 (2013) 7-22
[6] R. Ferrer et al., Phys. Rev. Res., 3 (2021) 043041
[7] D. Muenzberg et al., Atoms 2022, 10(2), 57
[8] J. Lantis et al., Phys. Rev. Res., 6 (2024) 023318

Speaker: Premaditya Chhetri (Johannes Gutenberg Universität)

Presentation_ID180_Chhetri.pptx

346 Quadrupole moments of neutron-deficient gold isotopes: investigating nuclear deformation

The neutron-deficient lead region is considered as having a large manifestation of deformation [1-3]. Within this region, neutron-deficient gold isotopes (Z = 79) exhibit unique phenomena: charge radii revealed a plateau of strong deformation around N = 101~107 region, known as “island of deformation” [4]; remarkable growth in deformation was also observed at 187Au as well as the large isomeric shift [5]; 11/2- spin states display parabolic trends in both magnetic and quadrupole moments of gold and other nearby isotopic chains, reflecting the effects of core-polarization and collectivity [6].

The basic properties of atomic nuclei, including masses, spins, electromagnetic moments, and radii serve as effective means for studying exotic nuclear structure. Laser spectroscopy enables precise extraction of the basic properties of atomic nuclei by measuring the hyperfine structure and isotope shifts of atoms, ions, and molecules [7]. The above phenomena have been extensively investigated by in source laser spectroscopy [8] which extracted the nuclear magnetic moments and charge radii of Au isotopes by measuring their atomic hyperfine structure. Nevertheless, to further understand the physics mechanism of the deformation in neutron-deficient gold, measurement of the quadrupole moment, another basic property of atomic nucleus and sensitive observable to nuclear deformation and shapes is essential, which however requires high-resolution laser spectroscopy technique.

Recently, by utilizing Collinear Resonance Ionization Spectroscopy (CRIS) experiment [9] at ISOLDE-CERN, we have measured the high-resolution hyperfine structure spectra of ground and long-lived isomeric states of 180-197Au. Quadrupole moments of 181-183,187-190Au have been extracted for the first time. This presentation will highlight the newly-measured properties of 181-183,187-190Au states, which will offer new insights into the underlying mechanism of “island of deformation” along the gold isotopic chain, and the shape coexistence in 187g,mAu.

Speaker: Yinshen Liu (School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China)

347 Nuclear radii in deformed relativistic Hartree-Bogoliubov theory in continuum

The study of exotic nuclei is one of the most fascinating frontiers in nuclear physics. Nuclear radii, including charge radius and neutron root-mean-square (rms) radius, are important properties for atomic nuclei, offering critical insights into the structure of exotic nuclei. In this work, based on the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), the charge radii for even-$Z$ nuclei with $8 \leq Z \leq 120$ are systematically investigated. The role of nuclear deformation is thoroughly analyzed, underscoring the necessity of microscopic and self-consistent approaches for precise charge radius descriptions. Furthermore, the neutron rms radii for even-$Z$ nuclei are also studied systematically based on the DRHBc theory. By combining these findings with neutron separation energies, potential neutron halos and their underlying microscopic structures are explored.

Speaker: Cong Pan (Anhui Normal University)

Presentation_ID242_Pan.pptx

Parallel Session: 6_Nuclear Structure (3)

Convener: Faical Azaiez (LNL-INFN)

348 Recent advancements in the strongly coupled many-body theory for nuclear spectral computation

I will present selected results on nuclear giant and pygmy resonances at zero and finite temperatures based on the recent advancements of the nuclear many-body theory [1-6]. The theory will be compactly introduced in the most general quantum field theory formalism with only the bare fermionic interaction input. A special focus will be placed on the emergent scale of the quasiparticle-vibration coupling (qPVC) with the order parameter associated with the qPVC vertex and an efficient treatment of the nuclear many-body problem organized around the qPVC hierarchy [1-3].

Self-consistent solutions of the relativistic Bethe-Salpeter-Dyson equation for the nuclear response function in medium-heavy nuclei will be presented and discussed. Low-multipole neutral and charge-exchange resonances in calcium, nickel, and tin mass regions will be analyzed in the context of the role of high-complexity configurations in reproducing spectral data [2,3,7]. Finite-temperature theory and implementations for astrophysically relevant low-energy dipole strength, beta decay rates, and electron capture rates will be overviewed in light of the temperature dependence of the nuclear spectral properties [4,5]. Finally, I will outline the prospect of the quantum equation of motion to generate complex configurations for the response of strongly correlated fermionic systems based on an example of the solvable Lipkin Hamiltonian [3].

References
[1] E. Litvinova and Y. Zhang, Microscopic response theory for strongly-coupled superfluid fermionic systems, Phys. Rev. C 106, 064316 (2022).
[2] E. Litvinova, On the dynamical kernels of fermionic equations of motion in strongly-correlated media, Eur. Phys. J. A59, 291 (2023).
[3] J. Novak, M. Q. Hlatshwayo, and E. Litvinova, Response of strongly coupled fermions on classical and quantum computers, arXiv:240502255.
[4] E. Litvinova and H. Wibowo, Finite-temperature relativistic nuclear field theory: an application to the dipole response, Phys. Rev. Lett. 121, 082501 (2018).
[5] E. Litvinova, C. Robin, and H. Wibowo, Temperature dependence of nuclear spin-isospin response and beta decay in hot astrophysical environments, Phys. Lett. B800, 135134 (2020).
[6] S. Bhattacharjee and E. Litvinova, Response of superfluid fermions at finite temperature, arXiv:2412.20751.
[7] M. Markova, P. von Neumann-Cosel, and E. Litvinova, Systematics of the low-energy electric dipole strength in the Sn isotopic chain, Phys. Lett. B860, 139216 (2025).

Speaker: Elena Litvinova (Western Michigan University)

INPC-2025_print_ID674_Litvinova.pdf

349 Quest for Nuclear Properties Beyond 132Sn Towards A=140

Neutron-rich nuclei close to the r-process path and waiting-point nuclei give extremely essential information about intrinsic nuclear properties vital both for nuclear physics and for astrophysics. They reveal how structure effects are of importance for theoretical modeling and can be crucial to understanding deviations of microscopic-macroscopic self-consistent models treating both neutron and gamma emission from data [1,2].

Such studies can be performed on long-lived excited and ground states, predominantly disintegrating by beta decay, on the neutron-excess side of the stability line. Some of the nuclei in the neighborhood of 132Sn, although exotic and neutron-rich, have rather simple structures, dominated by shell effects, and the evolution of low-lying proton-neutron orbitals [3,4].

Furthermore, these effects are possible to study in beta decay coincidences with gamma-ray detection. Recently, we performed several investigations reporting on the structure and FF / GT rates by spectroscopy [5,6]. Confronted with purely neutron emission detection methods and T1/2 measurements [8,9], they provide complementary and rather complete data sets to better describe astrophysical scenarios away from the stability line. Examples will be presented together with the available theoretical picture.

[1] P. Möller et al., At. Dat. Nucl. Dat. Tabl. 125, 1 (2019).

[2] F. Minato et al., Phys. Rev. C 104, 044321 (2021).

[3] R. Lozeva et al., Phys.Rev. C 98, 024323 (2018).

[4] R. Lozeva et al., Phys. Rev. C 110, 064303 (2024).
[5] V. Phong et al., Phys. Rev. Lett. 129, 172701 (2022).

[6] J. Liang et al. Nucl Dat. Sh. 168, 1 (2020).

Speaker: Radomira Lozeva (IJCLab)

350 In-beam gamma-ray spectroscopy of 136Te within the HiCARI project

With the arrival of the HiCARI campaign [1] to the RIBF facility at RIKEN (Japan), a series of in- beam gamma-ray spectroscopy experiments was performed in order to expand the previous spectroscopic information on exotic, neutron-rich nuclei of intermediate mass. Previously, incompatible results regarding the reduced transition probability for the decay of the first excited 2 + state, B(E2), in 136Te were reported from Coulex experiments and direct lifetime measurements using the fast-timing technique [2-5]. Due to the better energy resolution of the Ge detectors forming the HiCARI array, as compared to the previously used DALI2 NaI(Tl) array [6], in experiment NP1912-RIBF193 it was possible to extract, from the same data set, B(E2) values from the cross sections measured for the inelastic excitation on Au and Be targets on the one hand and the analysis of Doppler-shifted lineshapes on the other. The new results shed light on the conflict between transition strengths derived from Coulex and lifetime measurements reported for several nuclei in the literature. In addition, lifetimes of additional excited states of 136Te populated following one-neutron removal from 137Te were measured. Besides the experimental results obtained for 136Te, a comprehensive description of the employed analysis methods, including a discussion of all sources of systematic uncertainties, will be presented.

References
[1] https://www.nishina.riken.jp/collaboration/SUNFLOWER/devices/hrarray/index.php, accessed 12-01-2024
[2] J. M. Allmond et al., Phys. Rev. Lett. 118, 092503 (2017)
[3] M. Danchev et al., Phys. Rev. C 84, 061306(R) (2011)
[4] L.M. Fraile et al., Nucl. Phys. A 805, 218 (2008).
[5] V. Vaquero et al., Phys. Rev. C 99, 034306 (2019)
[6] S. Takeuchi et al., Nucl. Instr. Meth. A 763, 596 (2014)

Speaker: Jaime Acosta Loza (Instituto de Estructura de la Materia (CSIC))

Presentation_ID386_Acosta.pdf

351 The first measurement of the $0^+_3$ lifetime in $^{120}$Sn using thermal neutron capture

The semi-magic $^{120}_{50}$Sn$_{70}$ lies in the neutron mid-shell among the other stable Sn isotopes, where shape coexistence was observed with the signature of deformed 2p-2h bands built on excited $0^+$ states intruding into the yrast band that is built on the spherical ground state. However, the lifetime of the excited $0^+_3$ only has a lower limit of 6 ps in the literature, which prevents the study of transition strengths, and as a result, its structure is obscured.

The $0^+_3$ lifetime was measured in the first thermal neutron capture experiment, $^{119}$Sn(n,$\gamma^\text{many}$)$^{120}$Sn, at the Institut Laue-Langevin, where the world's highest-flux thermal neutron beam was delivered at $10^8$ n/cm$^2$/s at the target position on an isotopically enriched $^{119}$Sn target. Low-spin states in $^{120}$Sn were populated up to the neutron separation energy $S_n=9.1$ MeV, and the decaying gamma-ray cascades were detected with the Fission Product Prompt Gamma-ray Spectrometer (FIPPS) comprised of eight Compton-suppressed HPGe clovers coupled to an array of 15 LaBr$_3$(Ce) scintillation detectors. The LaBr$_3$(Ce) scintillators, which were used for gamma-ray detection and lifetime measurement using the Generalized Centroid Difference (GCD) method, have fast timing responses and are ideal for extracting lifetimes between 10 and a few hundred ps.

In total, there are $4.3\times10^9$ counts in the $\gamma\gamma\gamma$ cube where two LaBr$_3$(Ce) events were in coincidence with one HPGe following 14 days of beam on target.

Lifetime measurement for the $0^+_3$ state in $^{120}$Sn using the GCD technique will be presented. Additional lifetimes will also be measured where the $\gamma\gamma\gamma$ cascade's statistics permit, and detailed gamma-ray spectroscopy will be performed using the FIPPS data to significantly extend the $^{120}$Sn level scheme.

Speaker: Frank (Tongan) Wu (Simon Fraser University)

FWu_INPC2025.pdf

352 Isospin-Symmetric Island of Inversion

Protons and neutrons in nuclei are arranged in orbitals that follow a shell structure, with energy gaps at specific magic numbers. Experiments using radioactive beams have shown that these magic numbers vanish in some neutron-rich isotopes. This results in unusual arrangements, where configurations with nucleons scattered to higher energy orbitals are the most bound, forming what has been called "Islands of Inversion" [1]. These Islands of Inversion (IOI) have been explained through the shell model with variants of dynamical SU(3) symmetry [2].
The lifetime of the first $2^+$ states in $^{84}$Mo and $^{86}$Mo was measured in an experiment performed at the NSCL, Michigan State University. We discovered a dramatic structural change between the two isotopes from the experimental results. This has been understood as the boundary of an "Isospin-Symmetric Island of Inversion," where both proton and neutron excitations play an equal role and the evolution of collectivity is governed by three-nucleon forces.

References
[1] F. Nowacki, A. Obertelli and A. Poves, Prog. Part. Nucl. Phys. 120, 103866 (2021).
[2] S. M. Lenzi, F. Nowacki, A. Poves and K. Sieja, Phys. Rev. C 82, 054301 (2010).

Speaker: Jeongsu Ha (CENS, IBS)

Presentation_ID415_Ha.pdf

Parallel Session: 6_Nuclear Structure (4)

Convener: Aldric Revel (FRIB/MSU)

353 Insights into the nuclear structure and reaction dynamics of nuclear excitations

The nuclear structural properties of dipole excitations in nuclei of different mass regions are investigated using a theoretical approach based on energy-density-functional theory (EDF), quasiparticle-random-phase approximation (QRPA) and the quasiparticle-phonon model (QPM) [1]. The systematic comparison between QRPA and multiphonon QPM calculations in different nuclei shows that the behavior of the dipole strength at low energies is influenced by the competition between static and dynamic effects. The first effect is related to the mean field (MF) and the excitation of a pygmy dipole resonance (PDR) associated with neutron skin oscillations, while the second represents the coupling of the single-particle states with more complex excitations related to nuclear polarization and giant dipole resonance (GDR). These effects lead to a redistribution and fragmentation of the electric dipole strength (E1) at low energies, with particular emphasis on the neutron one-particle-one-hole (1p-1h) components of the QPM dipole state vectors [1-3]. The latter have been identified as doorway states common to neutron- and gamma-channels in (n,gamma) reactions [4]. As doorway states, the 1- QRPA excited states of the PDR contain mainly 1p-1h neutron configurations, which are expected to strongly influence the (n,gamma) cross sections and thereby affect isotope production in explosive stellar environments [1]. In these theoretical studies, the comparison of dipole spectral distributions obtained from Nuclear Resonance Fluorescence (NRF) experiments plays a special role [1]. Recent developments of our theoretical method, including a reaction theory [4,5], have been successfully applied to studies of (d,p) and (d,p gamma) reaction cross sections in neutron-excess nuclei. The theoretical observations show an increase in the neutron transfer reaction cross section in the PDR energy range, which was also observed experimentally, thus confirming the neutron origin of the PDR [4,5]. Furthermore, coincidence studies of dipole spectral distributions at low energies with various probes such as alphas, photons, protons, etc. are important tools to investigate the isospin dynamics of the nucleus. Experimentally, the determination of the dipole strength distribution and the associated photoabsorption cross section requires knowledge of the intensity distribution of the ground state transitions and their branching ratios. These quantities cannot be derived directly from the measured spectra. However, they can be determined theoretically from our microscopic calculations. An interesting new result observed in our studies of direct and cascade decay channels in 56Fe is an enhanced E1 below the neutron threshold in both direct and cascade spectral distributions, which, due to their spectroscopic properties, resemble PDR modes based on nuclear ground and excited states.
This work was carried out under the contract PN 23.21.01.06 sponsored by the Romanian Ministry of Research, Innovation and Digitalization and partially supported by ELI-RO-RDI-2024-AMAP of the Romanian Government.
[1] N. Tsoneva, H. Lenske, Energy-density functional plus quasiparticle-phonon model theory as a powerful tool for nuclear structure and astrophysics, Physics of Atomic Nuclei 79, 885–903 (2016) and refs. therein.
[2] T. Shizuma, S. Endo, A. Kimura, R. Massarczyk, R. Schwengner, R. Beyer, T. Hensel, H. Hoffmann, A. Junghans, K. Römer, S. Turkat, A. Wagner, and N. Tsoneva, Low-lying dipole strength distribution in 204Pb, Phys. Rev. C 106, 044326 (2022).
[3] P. -A. Söderström, M. Markova, N. Tsoneva, et al., Statistical properties and photon strength functions of the 112,114Sn isotopes below the neutron separation threshold, Phys. Rev. (2025).
[4] M. Spieker, A. Heusler, B.A. Brown, T. Faestermann, R. Hertenberger, G. Potel, M. Scheck, N.Tsoneva, M. Weinert, H.-F. Wirth, and A. Zilges, Accessing the Single-Particle Structure of the Pygmy Dipole Resonance in 208Pb, Phys. Rev. Lett. 125, 102503 (2020).
[5] M. Weinert, M. Spieker, G. Potel, N. Tsoneva, M. Müscher, J. Wilhelmy, and A. Zilges, Microscopic Structure of the Low-Energy Electric Dipole Response of 120Sn, Phys. Rev. Lett. 127, 242501 (2021).

Speaker: Nadia Tsoneva

Presentation_ID381_Tsoneva.ppt

354 Nuclear collective excitation based on the finite-amplitude method for QRPA

Nuclear collective excitation such as giant resonances provides valuable information on understanding the structure of finite nuclei and the equation of state for infinite nuclear matter. The quasiparticle random-phase approximation (QRPA) is a suitable theoretical framework for describing collective excitation as a superposition of the two-quasiparticle excitation, but it requires a large-dimensional matrix diagonalization and large computational resources.
The finite-amplitude method (FAM) [1] has been proposed as a solution to the QRPA problem under the presence of a one-body external field. The FAM is an iterative approach that makes it possible to calculate the strength function of giant resonance without additional truncation in the two-quasiparticle model space. Combined with a contour integration technique in the complex-energy plane, discrete low-energy collective states can be obtained [2]. The formulation based on the contour integration enables us to compute various QRPA solutions such as the low-energy collective modes, beta-decay rates, zero-energy pairing rotational modes, sum rules, and the nuclear matrix elements of the double-beta decay. I will review the recent progress and applications of the FAM for various problems including recent extensions for further reduction of the computational cost based on the reduced basis method.

[1] T. Nakatsukasa, T. Inakura, and K. Yabana, Phys. Rev. C 76, 024318 (2007).
[2] N. Hinohara, M. Kortelainen, and W. Nazarewicz, Phys. Rev. C 87, 064309 (2013).

Speaker: Nobuo Hinohara (University of Tsukuba)

Presentation_ID684_Hinohara.pdf

355 Exploring exotic dipole excitations into pygmy and toroidal modes

Exotic dipole excitations, such as Pygmy Dipole Resonances (PDR) and Toroidal Dipole Resonances (TDR), provide valuable insights into nuclear dynamics and structure. The PDR, associated with neutron skin oscillations, represents an excitation mode where weakly bound neutrons oscillate against the core. In contrast, the TDR, characterized by vortical nucleon motion, introduces a distinct mechanism involving nuclear currents rather than density oscillations. While these modes are predicted to coexist in the same low-energy region, their relationship remains unclear.
In this study, we focus on the PDR in selected Mo isotopes using the Gogny HFB+QRPA framework. We analyze dipole response functions and transition densities to identify PDR candidates and investigate their microscopic structure. Preliminary insights into the TDR are also presented, highlighting its unique features and potential connection to neutron skin thickness. Future work will further explore the interplay between these exotic dipole modes and their implications for nuclear structure and astrophysical nucleosynthesis.

This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 with support from LDRD Projects No. 25-LW-063.

Speaker: Eun Jin In (Lawrence Livermore National Laboratory)

Presentation_ID176_In.pdf

356 Pygmy Dipole Resonance and its evolution in the Sn mass region studied with the Oslo method

The pygmy dipole resonance (PDR) is typically associated with an enhancement in the low-lying electric dipole response of stable and unstable heavy nuclei, appearing on top of the tail of the giant dipole resonance (GDR). Despite the ongoing debates regarding its origin, its emergence is commonly linked to the presence of the neutron excess and might potentially affect the neutron-capture rates and, thus, abundances of elements produced in heavy-element nucleosyntehsis [1]. A systematic investigation of the evolution of the PDR and the low-lying electric dipole strength in general in different isotopic chains with different theoretical approaches and experimental methods is therefore of interest for both general nuclear structure studies and astrophysical simulations.

This work presents a consistent systematic study of the low-lying electric dipole strength and the potential PDR in Pd, Cd, In, and Sn isotopes with the primary goal of investigating its evolution with increasing neutron number, comparing it with available theoretical approaches, and revealing a possible impact of this feature on the astrophysical radiative neutron-capture processes. The analysis involves a simultaneous extraction of the nuclear level densities and the dipole $\gamma$-ray strength functions (GSF) of the studied nuclei using the Oslo method [2]. Combining these data with available $(\gamma,n$) cross sections and the electric and magnetic dipole strengths from relativistic Coulomb excitation in forward-angle inelastic proton scattering [3] allows us to extract the low-lying $E1$ component from the total dipole strength. It appears to exhaust $\approx 1-3\%$ of the classical Thomas-Reiche-Kuhn (TRK) sum rule, being either nearly constant throughout the whole chain of isotopes or mildly increasing with neutron number. This is in contradiction with the majority of theoretical approaches, such as, e.g., relativistic quasiparticle random-phase and time-blocking approximations, which predict a steady increase in the PDR strength with neutron number. Moreover, a presumably isovector component of the PDR was extracted for $^{118-122,124}$Sn.

The GSFs and nuclear level densities of the studied nuclei were further used as inputs to constrain the cross sections and Maxwellian-averaged cross sections of $(n,\gamma)$ reactions on Cd and Sn isotopes using the reaction code TALYS [4]. The obtained results agree well with other available experimental data and the recommended values from the libraries. Despite a relatively small exhausted fraction of the TRK sum rule, the low-lying electric dipole strength makes a noticeable impact on the radiative neutron-capture cross sections in the studied isotopes, contributing up to 20% of the estimated total cross sections. Moreover, the presence of a PDR-like enhancement in the GSFs of $^{122,1124}$Sn was found to affect the production of Sb in the astrophysical $i$ process, providing new constraints on the uncertainties of the resulting chemical abundances from multi-zone low-metallicity Asymptotic Giant Branch stellar models.

[1] S. Goriely et al., Phys. Lett. B 436 (1998) 10-18.
[2] A. C. Larsen et al., Phys. Rev. C 83 (2011) 034315.
[3] S. Bassauer et al., Phys. Rev. C 102 (2020) 034327.
[4] A. Koning et al., Eur. Phys. J. 59 (2023) 131.

Speaker: Maria Markova (University of Oslo)

Presentation_ID108_Markova.pdf

357 Toroidal dipole mode in nuclei: recent results

The toroidal dipole resonance (TDR) is a remarkable example of the electric intrinsic vortical flow in nuclei [1-3]. In conventional hydrodynamics of gases and liquids, such a flow is known as a Hill’s vortex ring. TDR is a general feature of atomic nuclei independently on their mass number and shape. However, the unambiguous observation of the toroidal mode is yet a demanding task for the modern experiment.

We report a recent prediction of E1 toroidal mode in low-energy dipole states of 58Ni. The prediction is based on the data of inelastic scattering experiments with photons, electrons and protons [4,5]. The main attention is paid to (e,e’) data.

The major part of TDR is located at the same energy region as the pygmy dipole resonance (PDR) which is crucially important for various astrophysical problems and building the equation of state [1,2]. The interplay between PDR and TDR is discussed. As the relevant examples, dipole excitations in 40Ca and 48Ca are considered.

[1] V.O. Nesterenko, J. Kvasil, A. Repko, W. Kleinig, and P.-G. Reinhard, Phys. Atom. Nucl. 79, n.6, 842 (2016).
[2] A. Repko, V.O. Nesterenko, J. Kvasil, and P.-G. Reinhard, Eur. Phys. J. A 55, 242 (2019).
[3] V.O. Nesterenko, A. Repko, J. Kasil, and P.-G. Reinhard, Phys. Rev. Lett. 120, n.18, 182501 (2018).
[4] I. Brandherm, P. von Neumann-Cosel, R. Mancino, G. Martinez-Pinedo, H. Matsubara, V. Yu. Ponomarev, A. Richter, M. Scheck, and A. Tamii, Phys. Rev. C 110, 034319 (2024).
[5] P. von Neumann-Cosel, V.O. Nesterenko, I. Brandherm, P.I. Vishnevskiy, P.-G. Reinhard, J. Kvasil, H. Matsubara, A. Repko, A. Richter, M. Scheck and A. Tamii, arXiv:2310.04736v5[nucl-ex], accepted by Phys. Rev. Lett.

Speaker: Valentin Nesterenko (BLTP JINR)

Presentation_ID152_Nesterenko.pdf

18:30 Break

Banquet

Friday, 30 May

Parallel Session: 7_Fundamental Symmetries and Interactions in Nuclei

Convener: Ricardo Alarcon (Arizona State University)

358 Search for new physics beyond the Standard Model with precision measurements in nuclear beta decays

Precision measurements in nuclear beta decays are sensitive probes to test the foundations and symmetries of the Standard electroweak Model and to search for exotic couplings presently excluded by the V-A theory in processes involving the lightest quarks. The main aim of such measurements is to highlight deviations from the Standard Model predictions as possible indications of new physics, complementing high energy physics experiments. The sensitive parameters are often deduced from correlation studies between the very few bodies involved in the decay or from the shape of event distributions. This requires to perform very precise measurements using advanced technical methods installed on-line in radioactive nuclei production facilities. Data analysis also requires generating the most realistic simulations to take into account the relevant parameters of the experimental setup and their systematic effects on the measured quantities.
In this presentation, I will highlight some key experiments in which LPC Caen is involved and I will discuss perspectives, especially considered in the DESIR facility at GANIL.

Speaker: Etienne Liénard (LPC Caen)

Presentation_ID490_Lienard.pptx

359 Isospin breaking in isospin-hindered 47K beta decay: enhanced sensitivity to time-reversal

Isospin is not an exact symmetry of QCD. Though in most nuclear systems the Coulomb interaction is thought to dominate isospin symmetry breaking (ISB), strong interaction ISB has implications for several nuclear physics puzzles, ranging from the Nolen-Schiffer anomaly in mirror nuclear masses to the extraction of Vud from Fermi beta decay.

The main result of TRIUMF's atom trap for beta decay (TRINAT) in the 3 years since INPC2022 is not a standard model test, but rather a measurement of isospin breaking in the $^{47}$Ca nucleus fed by I$^\pi$=1/2$^+$ $^{47}$K beta decay. The nonzero asymmetry in direction of the nuclear recoils wrt the $^{47}$K spin directly implies that the 80% 1/2+ decay branch has a small Fermi component to interfere with the dominant Gamow-Teller piece. We have extracted from this measured recoil asymmetry a ratio of Fermi and Gamow-Teller matrix elements 0.098 $\pm$ 0.037 and a Coulomb matrix element 101 $\pm$ 37 keV [Kootte et al. PRCL 2024].

Unlike most previous existing beta decay measurements, our $^{47}$K result exhausts a large fraction of expected analog-antianalog mixing, calculable by schematic analytic expressions backed by RPA [Auerbach and Loc NPA 2022]. We attribute the relatively large measured Coulomb matrix element to the existence of only one 1/2$^+$ state in nearly doubly-closed $^{47}$Ca, so the antianalog configuration is not spread over many final states. We will review a number of measurements with analog-antianalog mixing in mind, including the recent measurement in $^{26}$P decay done at Lanzhou [Liu et al. PRL 2022].

The relatively large $M_F/M_{GT}$ will be helpful to our planned test of time-reversal symmetry by measuring the correlation $\hat{I} \cdot v_\beta \times v_\nu$ in spin-polarized $^{47}$K decay. Sensitivity to parity-even time-reversal odd isospin-breaking interactions in the final nucleus is enhanced because the small T-breaking matrix element is referenced to the Coulomb interaction matrix element, which is naturally much smaller than strong interactions [Barroso and Blin-Stoyle PLB 1973]. We need backing for these simple assertions from nuclear theory calculations of matrix elements of time-reversal breaking effective operators [Herczeg NP 1966].

Our measurement of the $\beta$ asymmetry in $^{37}$K decay [Fenker PRL 2018] can also be interpreted as a benchmark of ISB theory relevant to measurements of Vud. DFT-based calculations of ISB in mirror decay, including strong interaction ISB fit to the Nolen-Schiffer anomaly [Konieczka PRC 2022] produce quite different ISB in $^{37}$K than shell-model calculations with Coulomb matrix elements matched to IMME [Severijns and Towner 2008]. We hope by improved $\beta$ decay correlation experiments with TRINAT to distinguish these calculations.

Speaker: John Behr (TRIUMF)

Presentation_ID468_Behr.pdf

360 Probing the structure of the weak interactions

The Standard Model as a very successful theory of electroweak interactions postulates the basic assumption about the pure „V(ector)-A(xial vector)“ character of the interaction. Nevertheless, the existence of other types of weak interactions (Scalar, Tensor) is still not experimentally ruled out. Low-energy searches for these „forbidden components“ studying e.g. β-ν angular correlations in β-decay are complementary to high-energy experiments e.g. at the LHC.
The experimental project WISArD (Weak-Interaction Studies with 32Ar Decay) situated at the isotope separator ISOLDE/CERN probes the existence of these S/T currents in the weak interactions (or at least significantly improve their current experimental limits) via the precise study of the kinematic shift of β-delayed protons emitted in the decay of 32Ar. Due to presence of both Fermi and Gamow-Teller β-decays, both the S and T currents can be searched for simultaneously. The experiment aims to reach a sensitivity limit of 0.1% .
The experimental apparatus consists of a cryostat with a superconducting 9T magnet and a dedicated system of particle detectors installed in the magnet bore around a thin catcher foil, where radioactive 32Ar ions delivered by ISOLDE are implanted. The presence of the strong magnetic field allows to spatially separate positrons and protons allowing to observe them with different detectors thus providing low background for the β-p coincidences. The precise measurement of the deformed β-delayed proton spectrum due to kinematic shift enables investigating the shape of the energy spectrum of recoiling ions after the β-decay which is sensitive to the possible admixture of S/T components in the weak interaction.
The successful proof-of-principle measurement performed in 2018 using existing equipment provided already an interesting result [1]. Since then several major upgrades were installed [2] and in May 2024 a full data taking was performed aiming to reach a competitive result at the per-mil level of uncertainty for the angular correlation coefficient.
The current status of the WISArD setup, newest experimental results and perspectives as well as plans for future will be presented.

References:
[1] V. Araujo-Escalona et al., Phys.Rev. C101(2020) 055501
[2] D.Atanasov et al., Nucl.Instr.Meth. A1050 (2023) 16159

Speaker: Dalibor Zakoucky (Nuclear Physics Institute of ASCR, Rez near Prague, Czech Republic)

Presentation_ID228_Zakoucky.pdf

Presentation_ID228_Zakoucky.pptx

361 Improved Search for Tensor Interactions in Nuclear Beta Decay

Improved Search for Tensor Interactions in Nuclear Beta Decay

X. Fléchard$^1$, R. Garreau$^1$, T.E. Haugen$^2$, L. Hayen$^1$, M. Kanafani$^1$, S. Leblond$^3$, E. Liénard$^1$, X. Mougeot$^3$, O. Naviliat-Cuncic$^{1,2,4}$, A. Rani$^1$, J-C. Thomas$^5$, S. Vanlangendonck$^6$
$^1$Université de Caen Normandie, ENSICAEN, CNRS/IN2P3, LPC Caen UMR6534, F-14000 Caen, France
$^2$Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing 48824 MI, USA
$^3$Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), 91120 Palaiseau, France
$^4$International Laboratory for Nuclear Physics and Nuclear Astrophysics, MSU-CNRS, East Lansing, MI, USA
$^5$Grand Accélérateur National d’Ions Lourds (GANIL), CEA/DRF-CNRS/IN2P3, Caen, France
$^6$KU Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan 200D, Leuven, B-3001, Belgium

Precision measurements in nuclear beta decay are sensitive probes to search for New Physics in the electroweak sector. In particular, the measurement of the beta-particle energy spectrum gives direct access to the Fierz interference term, the most sensitive parameter to search for phenomenological scalar or tensor couplings involving left-handed neutrinos. The goal of the bSTILED (b: Search for Tensor Interactions in nucLear bEta Decay) project is to measure the beta energy spectrum in the pure Gamow-Teller transition of $^6$He and extract the Fierz interference term with a precision at the permil level. The choice of the 6He nucleus ensures that the theoretical description of the beta energy spectrum does not limit the sensitivity goal. Using a ${4 \pi}$ calorimetry technique with the $^6$He nuclei implanted in the bulk of a detector, or confined between two detectors, also fully suppress the main instrumental effect associated with electron backscattering. Within the first phase of the project, two experiments have been carried out at GANIL, one with a low-energy (25 keV) and the other with a high-energy (312 MeV) beam of $^6$He. The analysis of both experiments are in progress and should each provide competitive constraints on tensor couplings. The second phase of the project will rely on the careful study of the pros and cons of the two techniques in order to improve the most promising approach and achieve so a level of sensitivity beyond the reach of the LHC.

Speaker: Xavier Fléchard (Université de Caen Normandie, ENSICAEN, CNRS/IN2P3, LPC Caen UMR6534, F-14000 Caen, France)

Presentation_ID281_FLECHARD.pdf

362 MORA (Matter's Origin from Radioactivity) first results

Around us we see an universe filled with galaxies, stars and planets like ours. But when we look back to the Big Bang and the processes that created the matter in it, at first we observe that there should have been created the same amount of matter and antimatter, consequently the universe would be empty or different than it is now. Sakharov suggested several conditions to explain the matter-antimatter asymmetry, one of them being the violation of the CP symmetry.

In the MORA experiment, we aim to measure the D triple-correlation of beta decay, which is non zero for violation of T symmetry in polarized nuclei, thus related to CPV. For this we use a symmetrical detector setup made of MCP’s, Phoswiches and Si detectors, to measure coincidences between beta emissions and recoil ions, product of the beta decay of trapped and polarized 23Mg ions, as well as measuring the polarization degree.

Here I will show the MORA setup in JYFL, how we plan to do the measurement, the challenges and successes that we encountered, and the latest experimental results concerning the proof of principle of polarized ions and the D-correlation measurement.

Speaker: Luis Miguel Motilla Martinez (GANIL/JYU)

Presentation Slides (PDF/PPT ONLY) PRESENTATION_ID39_Motilla_Martinez.pdf

Parallel Session: 7_Hot and Dense Nuclear Matter

Convener: Zhenyu Chen (Shandong University)

363 Probing the initial and final states of heavy ion collisions with open heavy flavor at CMS

The heavy flavor(HF) quarks are produced in the initial hard scattering of heavy ion collisions. This allows us to access information from the very early stage of the collision and the intermediate stages, especially the strong interaction with the medium, supposedly created with a high density and temperature, so-called quark-gluon-plasma. The observed HF hadrons encapsulate the information, requiring comprehensive investigation to fully understand the underlying effects. In this talk, recent results on open HF measurements from CMS are presented. The nuclear modification factors of charm and beauty hadrons are compared in different system sizes to understand cold and hot nuclear matter effects. The correlation measurements of the open HF are also presented to allow us to investigate further specifics such as medium energy loss and the initial production mechanism. The results are compared with the model predictions.

Speaker: Soohwan Lee (Korea University)

soohwan_lee_openHF_v1.pdf

364 Heavy quark mass and potential in quark-gluon plasma

We study the thermal production of charm quarks in relativistic heavy-ion collisions as at RHIC and LHC energies. Our study is based on the off-shell parton-hadron-string dynamics (PHSD) transport approach, which describes the full-time evolution of heavy-ion collisions on a microscopic basis with hadronic and partonic degrees of freedom. The sQGP is realized within the effective dynamical quasi-particle model (DQPM), which is adapted to reproduce lattice QCD results for the thermodynamic observables of the sQGP. Based on the success of the DQPM in describing the spatial diffusion coefficients $D_s$ from lQCD, we evaluate the production of charm quark pairs by rotating the Feynman diagrams so that the incoming charm quark and the outgoing light parton are swapped in elastic scattering diagrams. Charm quark annihilation is realized by detailed balance. We find that the number of thermally produced charm quark pairs strongly depends on the charm quark mass in the QGP. While for the heavy charm quarks of mass $m_c=1.8$ GeV it is subdominant compared to the primary charm production by binary nucleon-nucleon collisions, the numbers of primary and thermal charm quarks become comparable for a smaller (bare) $m_c=1.2$ GeV. Compared to the experimental data on the $R_{\rm AA}$ of $D$ mesons in heavy ion collisions at RHIC and LHC energies, it is more favorable for charm quarks in the QGP to gain additional mass due to thermal effects than to have a low bare mass [1].

Assuming that the number densities of the heavy flavor in the hadron gas and in the QGP are the same at $T_c$, since the phase transition is crossover at low $\mu_B$, we obtain the effective mass of the heavy quark at $T_c$ from the comparison with the hadron resonance gas model, which well describes the particle yield in heavy-ion collisions.
We find that the charm quark mass at vanishing baryon chemical potential is about 1.8 GeV [2], which is in agreement with our results from thermal charm production in heavy ion collisions. The mass increases slightly with increasing baryon chemical potential and then decreases.
On the other hand, the anticharm quark mass decreases steadily with increasing baryon chemical potential.

The heavy quark mass in QGP is related to the heavy quark potential at a large distance. We test three different heavy quark potentials, namely the free and internal energies of the heavy quark pair in QGP, and the unscreened potential recently proposed by the HotQCD Collaboration [3] through the thermal production of charm quarks in heavy ion collisions. We find that the free energy potential overestimates the charm production in heavy-ion collisions at the LHC, while the unscreened potential produces results closest to the experimental data from the ALICE collaboration among the three potentials [4].

[1] T. Song, I. Grishmanovskii, O. Soloveva and E. Bratkovskaya, Phys. Rev. C 110, no.3, 034906 (2024).
[2] T. Song and Q. Zhou, Phys. Scr. 99, 125304 (2024).
[3] A. Bazavov et al. [HotQCD], Phys. Rev. D 109, no.7, 074504 (2024).
[4] T. Song, J. Zhao and I. Grishmanovskii, [arXiv:2411.07383 [nucl-th]].

Speaker: Taesoo Song (GSI)

inpc-heavyquark (3).pdf

365 New high-precision measurement of the nuclear modification of prompt and nonprompt charmonia at unprecedently high ($p_{\mathrm{T}}$) in PbPb collisions with CMS

Quarkonia serve as powerful probes for investigating heavy quark dynamics and bound state behavior across multiple scales in heavy ion collisions. The production of prompt charmonia primarily reflects interactions between charm quarks and medium components, while nonprompt charmonia, produced through B hadron decay, illuminate beauty quark behavior. High-$p_\mathrm{T}$ measurements provide novel insights into color charge energy loss within the medium. Leveraging the extensive PbPb collision dataset from CMS, we present highly precise nuclear modification factors for both prompt and nonprompt J/$\psi$ and $\psi$(2S) mesons, along with their relative ratios. Our prompt measurements reach unprecedented $p_\mathrm{T}$ ranges for quarkonia in heavy ion collisions. These comprehensive measurements will provide crucial insights into the sequential suppression of heavy quark bound states in the quark-gluon plasma, while the high-precision nonprompt data will significantly constrain the degree of beauty quark interactions within the medium.

Speaker: Gyeonghwan Bak (Chonnam National University)

Presentation_ID660_Bak.pdf

366 Heavy quark suppression and anisotropic flow at intermediate momentum

We discuss heavy quark diffusion and radiation in an intermediate-momentum regime where finite mass effects are significant. Based on the collision kernel for diffusion, elastic scattering and semi-collinear gluon-bremsstrahlung can be consistently incorporated into a Boltzmann equation that involves the heavy quark diffusion coefficient. Using the running coupling constant and the diffusion coefficient constrained by lattice QCD data, we calculate the nuclear modification factor and the elliptic flow which are induced by the collisional and radiative energy loss of heavy quarks. The numerical results indicate that medium modifications by two types of energy loss are distinguishable and the significance of the radiative effect is determined by the momentum and temperature dependence of the diffusion coefficient. In hydrodynamically expanding thermal media, the momentum-dependent transition between two mechanisms and the radiative influence on the observables are discussed.

Speaker: Juhee Hong (Yonsei University)

Presentation_ID469_Hong.pdf

367 Towards optimally sensitive heavy quarkonium observables in heavy-ion collisions

To fully exploit the high precision data on heavy quarkonium, collected at the LHC in run2 and the ongoing run3, to improve our understanding of hot nuclear matter and the Quark-Gluon plasma, novel observables beyond R_AA and v_2 are called for.

Using the open quantum systems language, recently introduced in the study of in-medium heavy quarkonium [1], we take inspiration from cold atom metrology [2] to design observables, which are optimally sensitive to particular medium properties. Here we report on the construction of optimal observables [3] for bulk temperature, based on the Quantum Brownian Motion Lindblad equation [4].

[1] A. Rothkopf Phys.Rept. 858 (2020) 1-117
[2] M. Mehboudi et.al. Phys. Rev. Lett. 122, 030403 (2019)
[3] V. López-Pardo, A. Rothkopf (work in progress)
[4] V. López-Pardo (2024) 3d High Temperature Quarkonium Lindblad Dynamics Solver https://zenodo.org/records/14011860

Speaker: Alexander Rothkopf (University of Stavanger / Korea University)

INPC25_Rothkopf_FINAL.pdf

368 Investigation of charm and beauty quark hadronisation through charm hadron measurements with ALICE

Measurements of the production of heavy-flavour hadrons performed at the LHC in recent years have provided crucial insights into the hadronisation mechanism of heavy quarks.
The enhancement of baryon-to-meson production yield ratio observed in pp collisions compared to that in $\mathrm{e}^{+}\mathrm{e}^{-}$ collisions cannot be described by models developed under the traditional approach based on the assumption of universal quark fragmentation.
This observation has led to consider further hadronisation scenarios, such as colour reconnection mechanisms beyond the leading-colour approximation, coalescence mechanisms forming hadron and statistical hadronisation model including the feed-down from excited states of hadron which are not measured yet.
Precise measurements of heavy quarks are essential to understand how they hadronise into specific hadrons in hadronic collisions and to provide constraints for model development.

ALICE had studied the hadronisation mechanism of charm and beauty quarks by measuring prompt and non-prompt charm hadrons using data samples collected during Run 2.
With the upgraded ALICE detector during last LHC long shutdown 2 (LS2), ALICE is performing the precise measurements of prompt and non-prompt charm hadrons over an extended $p_{\mathrm{T}}$ interval.
Measurements performed with a larger data sample and improved spatial resolution are anticipated to provide further insights into the hadronisation mechanism of heavy quarks.

In this contribution, the final results of prompt charm hadrons ($\mathrm{D^0}$, $\mathrm{D^+}$, $\mathrm{D_{\mathrm{s}}^+}$, $\Lambda_{\mathrm{c}}^{+}$ and $\Xi_{\mathrm{c}}^{0,+}$) in pp collisions as well as $\Lambda_{\mathrm{c}}^{+}$ and $\Xi_{\mathrm{c}}^{0}$ in p--Pb collisions obtained with data samples collected during Run 2 will be presented.
The final results of non-prompt charm hadrons ($\mathrm{D^0}$, $\mathrm{D^+}$, $\mathrm{D_{\mathrm{s}}^+}$ and $\Lambda_{\mathrm{c}}^{+}$) in pp collisions will be discussed and compared with those of prompt charm hadrons.
The $\mathrm{c\overline{c}}$ and $\mathrm{b\overline{b}}$ production cross section per unit of rapidity at midrapidity ($\mathrm{d}\sigma/\mathrm{d}y \vert_{|y|<0.5}$) will also be presented.
Furthermore, new ALICE measurements of prompt and non-prompt charm hadrons in pp collisions using the data samples collected during Run 3 will be introduced.

Speaker: Jaeyoon Cho (Inha University)

JaeYoon_25INPC_ALICEheavyFlavourHadronisation_20250530_ver3.pdf

Parallel Session: 7_Nuclear Astrophysics

Convener: Dahee Kim (Center for exotic nuclear studies, Institute Basic Science)

369 Plasma Environment for Thermal Nuclear Reactions in Nucleosynthesis

We examine the effects of plasma on nucleosynthesis and propose methods to directly measure thermal nuclear reactions under astrophysical conditions, accounting for plasma effects. These effects are incorporated by solving the Boltzmann equation for photons, addressing both longitudinal and transverse components, which alter the dielectric properties and susceptibility of plasmas composed of ions and dense electrons. As a manifestation of plasma-induced dynamical screening, we derive a modified Gamow factor by revisiting the conventional assumptions used in its formulation.
Our analysis reveals that the traditional Gamow factor assumption is invalid for light nuclei, leading to penetration probabilities (PPs) that depend on the nuclear potential depth for such nuclei. By using potential depths calibrated to experimental fusion cross-section data, we show that PPs for light nuclei—such as D+D, D+T, D+3^33He, p+D, p+6^66Li, and p+7^77Li—are significantly enhanced compared to predictions from the conventional form, particularly near the Coulomb barrier. This enhancement reduces the Gamow peak energy by a maximum factor of 5.3 relative to the standard model.
These findings have important implications for determining the accessible energy range in low-energy nuclear reaction experiments based on the Gamow peak energy and for understanding electron screening effects in typical astrophysical environments.

Speakers: Myung-Ki Cheoun (Soongsil University), Prof. Myung-Ki Cheoun (Soongsil University & OMEG Institute)

Plasma Nuclear Physics_Short.pptx

370 Systematic Investigations of Scandium and Vanadium in Galactic Chemical Evolution

Scandium and vanadium are primarily synthesized in core-collapse supernovae, but significant discrepancies remain between observational abundance ratios ([Sc/Fe], [V/Fe]) and predictions from Galactic Chemical Evolution (GCE) models. These discrepancies highlight gaps in our understanding of the production mechanisms for these elements. Neutrino interactions and jet-like explosions have been proposed as potential solutions for enhancing scandium and vanadium yields, though these processes have yet to be fully integrated into GCE models.
Recent studies have suggested additional mechanisms: stellar rotation and O-C shell mergers during hydrostatic burning can enhance scandium production, while vanadium abundances may be influenced by the SNIa yields, particularly in high-metallicity environments.
We present a systematic investigation of scandium and vanadium abundances using initial rotational velocity and the initial mass function as key parameters. The code was validated against well-established element abundances in the Milky Way, ensuring its reliability for investigating alternative yields and scenarios for the target elements.
By incorporating these factors into a refined GCE framework, we address the discrepancies and improve the predictive power of theoretical models for these critical iron-peak elements.

Speaker: Soonchul Choi (CENS/IBS)

Presentation_ID491_CHOI.pptx

371 Mystery of decay acceleration of nuclear cosmochronometer 176Lu

A mete-stable isotope 176Lu has been used as a nuclear cosmochronometer for evaluating the ages of formation of parent bodies of meteorites and mantle-crust formation of planets and asteroids. However, there have been two critical problems. First, the measured values of the half-life of 176Lu are in the wide range of (3.5-4.1)x10^10 y. Second, the half-life values obtained from by analysis of some meteorites such as angrite and eucrites are much shorter than the values obtained from the other meteorites and terrestrial rocks. This suggests a unknown process that accelerates decay of 176Lu. For the mechanism, decay acceleration through an isomer with a half-life of 3.7 h excited by (gamma, gamma’) reactions from extremely high-flux unknown gamma-ray sources near the solar system. Recently, we have measured the most accurate value of the half-life of 176Lu using a method independent of the uncertainties in the previously used methods. This result has verified the possibility of the decay acceleration in some meteorites. We have proposed decay acceleration by high energy neutron irradiation generated by high-energy cosmic-rays. To demonstrate this process, we have measured decay of the isomer of 176Lu using neutrons with MeV energies generated by high power laser. This method has an advantage that the generated energy spectrum is similar with that of the cosmic neutrons. In addition, the Hayabusa 2 project give us samples from the Ryugu asteroid, which isotopic abundance may give a hint to explore the origin of the decay acceleration. We discuss our results and perspective for the mystery concerning 176Lu.

Speaker: Dr Takehito Hayakawa (National Institutes for Quantum and Radiological Science and Techonology)

Presentation_331_Hayakawa.pdf

372 High-precision nuclear chronometer for the cosmos

Nuclear chronometer provides an independent dating technique for the cosmos by predicting the ages of the oldest stars. Similar to geochronology, the ages are determined by comparing the present and initial abundances of long-lived radioactive nuclides. In nuclear cosmochronology, the present abundances can be obtained from the astrophysical observations whereas the initial abundances have to be determined by simulations of rapid neutron capture (r-process) nucleosynthesis. However, the previous Th/X, U/X, and Th/U chronometers suffer from the uncertainties of the r-process simulations, which leads to a poor identification on the cosmic age. Here we show that the precision of the nuclear chronometer can be significantly improved by synchronizing the three different types of nuclear chronometers, as it imposes stringent constraints on the astrophysical conditions in the r-process simulation. The new chronometer (Th-U-X) reduces the uncertainties of the predicted ages from the astrophysical conditions, more than ±2 billion years for the Th/U chronometer, to within 0.3 billion years. By the Th-U-X chronometer, ages of the six metal-poor stars with observed uranium abundances are estimated to be varying from 11 to 17 billion years, two of which disfavor the young cosmic age of 11.4 billion years by a recent measurement of Hubble constant from angular diameter distances to two gravitational lenses. Our results demonstrate that the Th-U-X chronometer provides a high-precision dating technique for the cosmic age. For perspective, the Th-U-X chronometer can serve as a standard technique in nuclear cosmochronology. It will be even more appealing in case that the r-process site is identified whereas the corresponding detailed conditions remain unknown, as it can filter out unreasonable conditions by synchronizing nuclear chronometers.

Speaker: Xin-Hui Wu (Fuzhou University)

Presentation_ID9_Wu.pptx

Parallel Session: 7_Nuclear Reactions

Convener: Marina Petri (University of York)

373 Extract the n-n interaction strength and the space-time size of neutron emission using femtoscopic method

Neutron-Neutron strong interaction strength is of importance in understanding the charge symmetry breaking of nuclear force, as well as in describing the nuclear matter properties in neutron rich environment. Measuring the n-n scattering length is not feasible in direct scattering process because there is no neutron target available. However, it can be done by using the two-particle correlation function in heavy ion reactions. In this talk, I will present the measurement of the n-n correlation functions in 25 MeV/u $^{124}$Sn+$^{124}$Sn reactions with the Compact Spectrometer for Heavy IoN Experiment (CSHINE). The n-n scattering length $f_0^{nn}$ and effective range $d_0^{nn}$ has been extracted using Lednicky-Lyuboshitz approach. Meanwhile, the space-time size of the neutron emission has been extracted simultaneously. Clear momentum dependence of the source size has been observed.

Speaker: Zhigang Xiao (Department of Physics, Tsinghua University)

ZhigangXiao-2025-0530.pdf

374 Directed and elliptic flow parameters in 129,124Xe + 124,112Sn collisions at 100 MeV/u and 58,64Ni + 58,64Ni at 52 MeV/u

The symmetry energy is the term that depends on the neutron-proton asymmetry in nuclear equation of state of nuclei and nuclear matter. It is a critical parameter to understand not only the basic properties of nuclear matter, but also the stability of the neutron stars in the Universe. Over the last several decades, nuclear symmetry energy has been studied by comparing the experimental data from heavy-ion collisions with the model calculations. However, the conclusion has not yet been reached as many aspects remain unknown.

To shed some lights on the symmetry energy as well as the equation of state the INDRA and ALADIN Collaborations jointly performed the experiment on Xe + Sn collisions at around 100 MeV/u at GSI in Germany in 1998. In addition, more recently, the INDRA-FAZIA Collaboration obtained the Ni + Ni collision data at 52 MeV/u in 2019. Both studies utilized several isotopic combinations for the beam and target to explore potential isospin dependencies.

In this presentation, we summarize the analysis status of the flow parameters in 129,124Xe + 124,112Sn collisions at 100 MeV/u and 58,64Ni + 58,64Ni at 52 MeV/u. The observables include the directed-flow parameter in the reaction plane and the elliptic-flow parameter in the transversal plane for the various combination of the isotopes for the beam and target. Finally, the experimental data are compared with the theoretical calculations from the ImQMD model to draw any physics conclusions.

Speaker: Seon Ho Nam (Korea University)

Presentation_ID276_Nam.pdf

375 Symmetry energy and isoscaling property of fragments emitted in $^{14}$N, $^{20}$Ne + $^{112,116,124}$Sn at 18-30MeV/nucleon

The study of the symmetry energy term in nuclear equation of state (EOS), has been one of the most prominent research topics in nuclear astrophysics, both in the theoretical and experimental domains in the last decade. The importance of the symmetry energy lies on its dependence on nucleon density which finally determines the reaction rates involving electrons and neutrinos, particle abundances, and other factors in astrophysical scenarios like supernova dynamics, proto-neutron star evolution, the r-process, the long-term cooling of neutron stars, and the structure of cold-catalyzed neutron stars. The coefficient of symmetry energy, C$_{sym}$, can be measured from the isotopic compositions of the emitted fragments, through isoscaling property. It is basically a property of identical fragments emitted in reactions with different isospin asymmetry by which the ratio of the isotopes show an exponential dependence on N and Z of the isotope. Two reactions, 1 and 2, having the same temperature T, will exhibit isoscaling behavior if the ratio $R_{21}$ of the yields of a particular isotope having neutron and proton number N and Z respectively, emitted from the two reactions have an exponential relationship of the form,
\begin{equation}
\tag{1}
R_{21}=\dfrac{Y_2(N,Z)}{Y_1(N,Z)}= C exp{(\alpha N+\beta Z)}
\end{equation}
where, $Y_2(N,Z)$ and $Y_1(N,Z)$, are the yields of the isotope from the neutron rich system and neutron deficient system, respectively, C is the normalization constant, $\alpha$ and $\beta$ are the isoscaling parameters. The parameter $\alpha$ and $\beta$ have a relationship with C$_{sym}$, which is derived on the basis of statistical models, where the emitted fragments are considered to be at saturation density,
\begin{equation}
\tag{2}
\alpha =\dfrac{4C_{sym}}{T} \left[{\left(\dfrac{Z_{1}}{A_{1}}\right)}^2 -{\left(\dfrac{Z_{2}}{A_{2}}\right)}^2\right]
\end{equation}
where T is the common temperature for both systems; Z$_1$, A$_1$ and Z$_2$, A$_2$ are the atomic and mass numbers of the two multifragmenting systems.

In this paper, we shall show the dependence of symmetry energy on excitation energy (E$^{*}$) from the study of isoscaling property of intermediate mass fragments (IMF). The availability of the first beam at the K500 superconducting cyclotron has enabled such investigations over a range of excitation energies at VECC, Kolkata. The experiment was conducted using neon ion beams with energies 18 and 22 MeV/ nucleon, as well as nitrogen ion beams with energies of 19 and 30 MeV/ nucleon. Enriched $^{112}$Sn ($\sim$ 2.6 mg/ cm$^{2}$), $^{116}$Sn ($\sim$ 2.23 mg/ cm$^{2}$) and $^{124}$Sn ($\sim$ 2.81 mg/ cm$^{2}$), were used as targets. Fragments produced in the reactions $^{20}$Ne + $^{112,116,124}$Sn and $^{14}$N + $^{112,124}$Sn, were detected isotopically using silicon strip $\Delta$E - E detector telescopes. Experimentally obtained yields of different fragments have been normalized with the incident number of particles and number of target nuclei per unit area. The isotopic yield ratios of each element emitted from the reacting systems were plotted with neutron number N and fitted individually using Cexp($\alpha$N), while the isotonic yield ratios were plotted with atomic number Z and fitted with C$'$exp($\beta$Z). It was observed that isoscaling is well respected by the IMFs emitted in all reactions across the excitation energy range studied. The fitted parameters for both plots were found to be nearly identical.

Accurate determination of C$_{sym}$ from the isoscaling parameters requires precise measurements of the nuclear temperature of the composite systems formed during the nuclear reaction. In this study, two independent methods were employed to calculate the nuclear temperatures: the double isotope ratio method and the Fermi gas model. The values of C$_{sym}$ at a particular excitation energy were extracted using the average values of $\alpha$ and $\beta$ at that energy. The values obtained are approximately $\sim$ 26–20 MeV using the temperature from the Fermi gas model and $\sim$ 24–17 MeV using the double isotope ratio method, for E/A = 2.1 - 2.8 MeV. A decreasing trend of C$_{sym}$ with excitation energy is observed for E/A $>$ 2 MeV, consistent with previous studies. However, an anomaly is observed at E/A = 1.8 MeV, which may be attributed to the reduction or absence of multifragmentation below E/A = 2 MeV.

The experimental results were compared with the isospin-dependent hybrid model of nuclear multifragmentation [S. Mallik and G. Chaudhuri, Nucl. Phys. A 1002, 121948 (2020)]. In this model, the initial stages of the reaction, where the projectile and target fuse, is taken care of by dynamical approaches. The fragmentation of the excited system is described by a statistical model. The model calculation involves three distinct stages: The initial stage of the reaction is studied using the Boltzmann-Uehling-Uhlenbeck equation in an isospin-dependent transport model (BUU@VECC-McGill). Pre-equilibrium emission in the early stages can influence the yields of the emitted fragments. Therefore, excitation and isospin asymmetry of the compound nuclear system, formed after the dynamical stage are determined by considering 98\% of the total mass, with the remaining part attributed to pre-equilibrium emission. The Canonical Thermodynamical Model (CTM) is then applied to analyze the fragmentation of the compound nuclear system, using the excitation energy (E) and isospin asymmetry obtained from stage (i). (iii) Finally, the secondary decay of the excited fragments produced in stage (ii) is studied using the evaporation model based on Weisskopf's formalism. The freeze-out volume in the calculation is assumed to be three times the normal volume of the compound nuclear system. The model satisfactorily reproduces the experimental results, C$_{sym}$, at E/A = 2.1, 2.6 and 2.8 MeV, but fails for 1.8 MeV. The experimental value of C$_{sym}$, E/A =1.8 MeV, much less that the theoretical value, which may be due to reduction or vanishing of multifragmentation below E = 2 MeV/nucleon.

Speaker: Samir Kundu (Variable Energy Cyclotron Centre)

Presentation_ID55_Kundu.pdf

376 Heavy Ion Collision Simulation using the Quark Meson Coupling Model

Heavy-ion collisions, particularly those involving rare-isotope beams, provide a crucial opportunity to investigate properties of high-density nuclear matter. To study these collisions, we use the DaeJeon Boltzmann-Uehling-Uhlenbeck (DJBUU) transport model, which solves the Relativistic Boltzmann-Uehling-Uhlenbeck equation via the test-particle method. In this framework, nucleons propagate within relativistic mean fields and undergo collisions with their in-medium cross sections. Recently, we have incorporated the Quark Meson Coupling (QMC) model, which successfully describes nuclear matter and neutron stars, into DJBUU to enable its application to heavy-ion collisions. Compared with the previously implemented Quantum Hadron Dynamics (QHD) model, QMC employs quark-meson couplings to describe nuclear forces, offering advantages such as a more natural description of the effective mass of the $\Delta$ baryon. This turned out to be crucial for pion production.
In this work, we validate the QMC-based approach for heavy-ion collisions by comparing simulation results from QMC and QHD within the DJBUU framework. Preliminary results indicate that the overall trends for both models are similar, but QMC tends to yield slightly higher baryon densities and fewer pions than QHD.

Speaker: Dae Ik Kim (Pusan National University)

Presentation_DJBUU+QMC_Daeik.pdf

Presentation_DJBUU+QMC_Daeik.pptx

377 Hints of the momentum-dependent nucleon effective mass splitting via heavy ion collisions

The neutron-proton effective mass splitting (Δm^*_np) is investigated through analyses of heavy-ion collisions using the improved quantum molecular dynamics (ImQMD) model with both standard and extended Skyrme interactions. We find a strong correlation between the slope of the neutron-to-proton yield ratio with respect to the kinetic energy (i.e., Sn/p) and Δm^*_np, with correlation coefficients exceeding 0.80. For the ¹²⁴Sn + ¹²⁴Sn system, this correlation reaches 0.928. By comparing theoretical predictions with experimental data, we reveal a novel dependence of the neutron-proton effective mass splitting on momentum: at low kinetic energies, the data favor m^*_n > m^*_p, which is consistent with the nucleon-nucleus scattering analysis, while at high kinetic energies, they favor m^*_n < m^*_p, which is an extended understanding of effective mass splitting at high kinetic energy region. This finding provides the first direct evidence that the momentum-dependent symmetry potential likely decreases initially and then increases with momentum.

Speaker: Yingxun Zhang (China Institute of Atomic Energy)

presentation-ID688-Zhang.pptx

Parallel Session: 7_Nuclear Structure (1)

Convener: Giovanna Benzoni (INFN-Milano)

378 Revealing the nature of yrast states in neutron-rich polonium isotopes

Polonium isotopes having two protons above the shell closure at $Z = 82$ demonstrate a wide variety of high-spin isomeric states across the whole chain.
The structure of neutron-deficient isotopes up to $^{210}$Po ($N = 126$) is well established thanks to being easily produced through different methods, as opposed to their neutron-rich counterparts for which not much information is currently available and only selective techniques can be used for production.
The presentation will focus on first fast-timing measurements of yrast states up to $8^+$ in $^{214,216,218}$Po isotopes produced in the β-decay of $^{214,216,218}$Bi at the ISOLDE Decay Station of ISOLDE-CERN. The only half-life value previously available in literature corresponding to the $8^+$ state in $^{214}$Po was 20 times larger than the presently reported one. The extracted transition probabilities $B(E2)$ values provide a crucial test of the different theoretical approaches describing the underlying configurations of the yrast band.
The new experimental results are described by shell-model calculations using the KHPE and H208 effective interactions and their pairing modified versions. These results contradict the previous expectations of isomerism for the $8^+$ yrast states in neutron-rich polonium isotopes, showing an increase in configuration mixing as opposed to the simple seniority scheme applicable in the neutron-deficient cases.

Speaker: Razvan Lica (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), Romania)

Presentation_ID305_Lica.pdf

379 Progress on Decay and Resonance Laser Ionisation Spectroscopy of Neutron Rich Polonium at ISOLDE

Beyond Bi ($Z=83$) and the $N=126$ neutron shell closure, the longest lived isotopes of each element are found beyond $N=134$. This is due to the fast alpha decay of isotopes towards the $N=126$ shell closure. While this has been well established, information on the ground state properties is missing for Po ($Z=84$) isotopes. Moreover, this region is known for the occurrence of octupole deformation in the ground state [1] and is of interest for ongoing searches for atomic electric-dipole-moments.

Polonium isotopes with $N\geq137$ have been observed in fragmentation studies, however, the half-life, $\alpha$-to-$\beta$-decay branching ratio and charge radius of $^{220}$Po remain unknown due to difficulties in measuring $^{220}$Po in fragmentation studies and producing pure beams in laser spectroscopy studies [2]. We have performed decay spectroscopy of $^{219, 220}$Po at CERN ISOLDE with the ISOLDE Decay Station (IDS) and the Alpha SETup (ASET). Laser spectroscopy measurements were performed, in the ion source, using IDS as a highly sensitive ionization rate detection setup. These investigations were made possible by utilizing a Perpendicularly Illuminated Laser Ion Source and Trap (PI-LIST) device [3], in LIST mode, to reduce the isobaric Fr contamination which previously prevented measurements at ISOLDE in this region. We present the first results for the half-life and $\alpha$-to-$\beta$-decay branching ratio of $^{220}$Po, the hyperfine structure and isotope shift measurements of $^{211, 217, 218, 219, 220}$Po including high-spin isomers in $^{211, 212}$Po, and preliminary analysis of the hyperfine structure of $^{219}$Po.

References
[1] L. P. Gaffney, P. A. Butler, M. Scheck, et al., “Studies of pear-shaped nuclei using accelerated radioactive beams,” Nature, vol. 497, no. 7448, pp. 199–204, May 1, 2013, issn: 1476-4687. doi:10.1038/nature12073. [Online]. Available: https://doi.org/10.1038/nature12073.
[2] D. A. Fink, T. E. Cocolios, A. N. Andreyev, et al., “In-Source Laser Spectroscopy with the Laser Ion Source and Trap: First Direct Study of the Ground-State Properties of Po 217 , 219,” Physical Review X, vol. 5, no. 1, p. 011 018, Feb. 20, 2015, issn: 2160-3308. doi:10.1103/PhysRevX.5.011018. [Online]. Available: https : / / link . aps . org / doi / 10 . 1103 / PhysRevX . 5 . 011018 (visited on 07/23/2024).
[3] R. Heinke, M. Au, C. Bernerd, et al., “First on-line application of the high-resolution spectroscopy laser ion source PI-LIST at ISOLDE,” Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, vol. 541, pp. 8–12, Aug. 2023, issn: 0168583X. doi: 10.1016/j.nimb.2023.04.057. [Online]. Available: https://linkinghub.elsevier.com/retrieve/pii/S0168583X23001945 (visited on 06/22/2024).

Speaker: Jack Shaw (KU Leuven, Instituut voor Kern- en Stralingsfysica, B-3001 Leuven, Belgium)

Presentation_ID494_Shaw.ppt

380 Axial quadrupole and octupole dynamics in even-even and odd mass nuclei

A quadrupole-octupole axially symmetric geometric model is proposed for the description of alternate parity bands in even-even nuclei [1,2] and parity doublet bands in odd mass nuclei [3]. The shape and the dynamical behaviour of the considered nuclei are ascertained from the phenomenology of the adopted model and the obtained parameters. The model parameters exhibit a regular evolution as a function of neutron number [3,4]. As a result, the quadrupole shape phase transition around N=90 is found to be accompanied by the increase of the vibrational character for the octupole deformation. A similar critical point is also identified in the A = 224–228 mass region of the Ra and Th nuclei. It marks different stages of the transition between static and dynamic octupole deformation with a specific spin dependence for the electromagnetic transitions. Model extrapolations are performed for various types of excited states, for which distinguishing spectral signatures are forwarded [5].

[1] R. Budaca, P. Buganu, A. I. Budaca, Phys. Rev. C 106, 014311 (2022).
[2] R. Budaca, A. I. Budaca, P. Buganu, Phys. Scr. 99, 035309 (2024).
[3] R. Budaca, At. Data Nucl. Data Tables, 101692 (2024).
[4] R. Budaca, P. Buganu, A. I. Budaca, Il Nuovo Cimento C 47, 25 (2024).
[5] R. Budaca, P. Buganu, A. I. Budaca, Eur. Phys. J. A 59, 242 (2023).

Speaker: Radu Budaca (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering)

Presentation_ID21_Budaca.pdf

381 Investigation of Alpha Formation Based on the Configuration Interaction Shell Model

Based on the configuration interaction shell model, the quartet amplitude is defined to calculate the formation probability of $\alpha$ particle during $\alpha$ decay. Within such theoretical framework, the $\alpha$ formation probability of Po isotopes are calculated. The results are consistent with the $\alpha$ formation probability extracted from the experimental $\alpha$ decay half-life.

Speaker: Cenxi Yuan (Sun Yat-sen University)

Presentation_597_Yuan.pdf

382 Lifetime measurements of low-energy octupole states in radium-224

For certain nuclei long-range octupole-octupole residual interactions can cause a reflection-asymmetric (pear) shape to occur. This octupole deformation, combined with quadrupole deformation, causes a separation between the centre of mass and centre of charge in the nucleus, resulting in a significant electric dipole (E1) moment. This effect enhances the strength of the E1 and electric octupole (E3) transitions, characteristic features of such nuclei.

The presence of these low lying J$^π$= 1$^-$and 3$^-$ is indicative of octupole deformation. An example of one of these nuclei is radium-224 which is octupole deformed in the ground state as evidenced by the observation of enhanced E3 transitions[1]. Their work measured a large E3 strength but could only give an upper limit on the reduced transition probability of the E1 transition (B(E1)).

The aim of this experiment was to measure the lifetimes of the low-lying J$^π$= 1$^-$and 3$^-$ states in radium-224 and, therefore, measure the E1 strength. This was done by observing the beta decay of francium-224 ions which were produced at the ISAC facility in TRIUMF. The lifetime of these states was measured by using the LaBr$_3$(Ce) detectors of the GRIFFIN array and the generalised centroid difference method. Measuring the lifetime of these states makes it possible to perform a direct measurement of the low-energy dipole response in radium-224 for the first time.

References

[1] L. P. Gaffney et al., “Studies of pear-shaped nuclei using accelerated radioactive beams,” Nature, vol. 497, pp. 199–204, May 2013.

Speaker: Dylan White (University of the West of Scotland)

Presentation_ID146_White.pdf

383 Fission isomer studies at IGISOL and FRS

The ‘island’ of fission isomers identified in the actinide region (Z = 92 - 97, N = 141- 151) originates from multi-humped fission barriers, which can be understood as the result of superimposing microscopic shell corrections to the macroscopic liquid drop model description. In a recent experiment, fission isomers $^{240f,242f}$Am have been produced with deuteron-induced reactions on a $^{242}$Pu target at the IGISOL facility in Jyväskylä, Finland. Measurements of their fission fragments with a background-free method have been performed. For the first time, the in-flight fragmentation and electromagnetic dissociation methods were applied at GSI for populating fission isomers. With the fragment separator (FRS) at GSI, the fragmentation of 1 GeV/u $^{238}$U projectiles gives access to isotopes that are hard or impossible to reach by light particle-induced reactions that are so far in use. In-flight separation with the FRS allows studying fission isomers with half-lives as short as 100 ns. Most importantly, it provides beams with high purity and enables event-by-event identification. Two detection methods were employed to study fission isomers with half-lives in the range of approximately 100 ns to 50 ms: beam implantation in a fast plastic scintillator, and beam thermalization in a cryogenic stopping cell at the FRS Ion Catcher followed by subsequent detection [1]. Results from these experiments will be presented in this contribution.

References
[1] J. Zhao et al., Proceedings of Science 419 (2023) PoS (FAIRness2022) 063.

Speaker: J. Zhao (Beihang University, Beijing, China)

Presentation_ID197_Zhao_v1.pdf

384 Structure of heavy actinides in the $^{252}$Fm region: recent results and future perspectives.

The existence of long-lived super heavy elements depends on the presence of shell gaps that increase nuclear stability against fission. The largest effects are expected in the so-called Island of Stability (IoS), where the next main spherical gaps are predicted to exist, near proton number $Z$=114, 120 and neutron number $N$=184. Small energy gaps occurring near $Z$=100,108 and $N$=152,162 also enhance the stability of heavy actinides and trans-actinides, creating a sort of "submerged rift" leading to the IoS. Notably, valence orbitals of nuclei in the heavy actinide region include some substates, lowered by deformation, of orbits predicted to give rise to the IoS. The properties of actinides near the deformed shell gaps thus provide imporant benchmarks for theoretical models that predict the location of the IoS and the properties of super heavy elements.
At the JAEA Tandem facility in Tokai, Japan, we have performed a number of $\gamma$-ray spectroscopy studies to deepen our understanding of the structure of actinides in the region near $^{252}$Fm, produced using multi-nucleon transfer reactions. In particular, we focused on the influence and role of the $Z$=100 and $N$=152 deformed shell gaps. Recent results, which include new information on $K$ isomers in $^{248}$Cf ($Z$=98,$N$=150)[1] and the ground state rotational band of deformed doubly magic $^{252}$Fm, will be presented.
Experimentally, one factor that limits the study of heavy actinides is the low detection efficiency for low-energy transitions (<60 keV), which are typical of rotational bands in this region. A possible solution, provided by an array of CdTe detectors that we are currently develping, will also be introduced.

[1] R. Orlandi et al., Phys. Rev C 106, 064301 (2022).

Speaker: Dr Riccardo Orlandi (Japan Atomic Energy Agency, Tokai, Japan)

contribution.pdf

Parallel Session: 7_Nuclear Structure (2)

Convener: Prof. Seonho Choi (Seoul National University)

385 The 36S(p,d)35S reaction: new results from an old tool

The neutron-removal reaction $^{36}$S($p,d$)$^{35}$S was studied at iThemba LABS up to an excitation energy of E$_x = 16$ MeV to investigate the effectiveness of the $N = 20$ shell closure and examine the neutron $d_{5/2} - d_{3/2}$ spin-orbit splitting in $^{36}$S. An unexpected and pronounced $j$-dependence of the cross-section angular distributions at forward angles enabled the study of spin-orbit splitting using cross section measurements alone.

The results indicate that the splitting between the reconstructed $d_{5/2}$ and $d_{3/2}$ single-particle spin-orbit partners increases from $^{36}$S to $^{40}$Ca, contrary to the generally observed trend predicting a decrease of approximately $\sim$450 keV. This atypical splitting offers a valuable test case for exploring the role of the tensor force, particularly because the neutron-proton tensor force counterbalances the spin-orbit force as protons occupy the $1d_{3/2}$​ orbital. These findings provide critical data to constrain state-of-the-art theoretical models, especially in evaluating the proton-neutron tensor component's impact.

Speaker: Retief Neveling (iThemba LABS)

Presentation_ID697_Neveling.pdf

386 Investigating the sd-shell structure of 16,17C via (d, p) transfer reactions

In unstable nuclei, single particle orbits undergo rearrangement, leading to various shell evolution phenomena, such as the new magic number $N=14$ and $N=16$ observed in neutron-rich O isotopes [1]. But in $^{16,17}\mathrm{C}$, the $N=14$ magic number disappear, and the $2s_{1/2}$ and $1d_{5/2}$ neutron orbits are nearly degenerate, which were proved by the close s- and d-wave states of them [2]. However, whether the $N=16$ magic number existing in $^{16,17}\mathrm{C}$ or not is still unclear in experiment, since the excited states with the valence neutron dominated by the $1d_{3/2}$ orbit (using “the $1d_{3/2}$ state” for short in the following text) in $^{16,17}\mathrm{C}$ were unbound states, and they were not observed in previous experiments.
In order to search for such kind of excited states in $^{16,17}\rm{C}$, we conducted the $^{15,16}\mathrm{C}(d,p) ^{16,17}\mathrm{C}$ experiments in inverse kinematics at the Radioactive Beam Line at Lanzhou (RIBLL1) in the Institute of Modern Physics (IMP) in 2022 [3,4]. As of now, we have completed the particle identification, and reconstructed the excitation energy spectra of $^{16,17}\mathrm{C}$ using the energies and angles of the recoil protons emitting to the backward angles with the missing mass method. According to the differential cross sections of each populated state comparing to the distorted wave Born approximation (DWBA) calculations, we found some candidates for the $1d_{3/2}$ state in the unbound states of $^{16,17}\mathrm{C}$. For $^{16}\mathrm{C}$, $1d_{3/2}$ states may lie around 8~10 MeV, and for $^{17}\mathrm{C}$ they may lie around 4~6 MeV. Further data analysis and theoretical calculations to determine if they are the $1d_{3/2}$ states or not are still in progress.

Reference:
[1] A. Schiller, N. Frank et al., Phys. Rev. Lett. 99, 112501 (2007).
[2] M. Stanoiu, D. Sohler et al., Phys. Rev. C 78, 034315 (2008).
[3] Pu W. L., Ye Y. L. et al., Nucl. Sci. Tech. 35, 12 (2024).
[4] Zhu H. Y., Lou J. L., et al. Nucl. Sci. Tech. 34, 159 (2023).

Speaker: Bolong Xia (Peking University)

Investigating the sd-shell structure of 16,17C via (d, p) transfer reactions-inpc2025.pptx

387 Probing exotic cross-shell interactions at N=28 with single-neutron transfer on 47K

Shell evolution in nuclei far from stability, such as those in the region of N ≥ 28 and Z < 20, is understood to arise from the complex interplay of orbital interactions, with different interactions accessible in unstable nuclei compared to stability. Experimental studies of these exotic regions provide stringent tests of modern shell model interactions, but are difficult to access experimentally. In this regard, the transfer reaction 47K(d,p)48K provides a unique opportunity to study the exotic pi(s1/2)-nu(fp) interaction in a near-doubly magic nucleus, owing to the pi(s1/2)^-1 ground state structure of 47K, which is near-degenerate with the `standard’ pi(d3/2)^-1 proton configuration in this region.

The first measurement of the 47K(d,p gamma)48K transfer reaction has been performed at GANIL, in inverse kinematics using a reaccelerated radioactive isotope beam. Heavy recoils, light ejectiles and prompt gamma-ray emissions were detected using the state-of-the-art MUGAST+AGATA+VAMOS experimental set-up. Through this work, the level scheme of 48K has been greatly extended with nine new bound excited states identified, spin-parities assigned and spectroscopic factors deduced. Detailed comparisons with SDPF-U and SDPF-MU shell-model calculations reveal a number of discrepancies between theory and experiment. Intriguingly, an apparent systematic overestimation of spectroscopic factors and a poor reproduction of the energies for 1− states suggests that the mixing between the pi(s1/2)^-1 and pi(d3/2)^-1 proton configurations in 48K is not correctly described using current interactions, challenging our descriptions of light nuclei around the N=28 island of inversion.

A complete analysis and discussion of the 47K(d,p gamma) reaction -- and the complementary 47K(d,t gamma) reaction -- will be presented.

Speaker: Charlie Paxman (GANIL)

Presentation_ID058_Paxman.pdf

388 Investigations near N=20 using nucleon transfer reactions with HELIOS and SOLARIS

Three reactions,$^{32}$Si(t,p)$^{34}$Si, $^{32}$Si($^{3}$He,d)$^{33}$P with the SOLARIS spectrometer and $^{34}$S(t,p)$^{36}$S with the HELIOS spectrometer, were measured in inverse kinematics at a 6.3 MeV/u incident energy in order to investigate the structure of nuclei around the “island of inversion”. Outgoing proton and deuteron spectra were measured from an angular range of ~20-40 degrees and populated excited states of $^{34}$Si, $^{33}$P, and $^{36}$S were identified at energies up to 5-7 MeV. In conjunction with classical recoil identification, some machine learning methods were used, including anomaly detection and multi-class classification predictive modeling. Measured proton angular distributions for the most populated states are used in comparison with distorted wave Born approximations (DWBA) calculations, including DWUCK and PTOLEMY, to make tentative spin assignments and extract spectroscopic amplitudes.

This research used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility. This work was supported by the US Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. This material is based upon work supported by NSF’s National Superconducting Cyclotron Laboratory which is a major facility fully funded by the National Science Foundation under award PHY-1565546; the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract Number DE-AC02-06CH11357 (Argonne) and under Award Number DE-SC0014552 (UConn); the Spanish Ministerio de Economia y Competitividad through the Programmes "Ramon y Cajal" with the grant number RYC2019-028438-I; the U.K. Science and Technology Facilities Council (Grant No. ST/P004423/1); and the International Technology Center Pacific (ITC-PAC) under Contract No. FA520919PA138. SOLARIS is funded by the DOE Office of Science under the FRIB Cooperative Agreement DE-SC0000661.

Speaker: Nate Watwood (Argonne National Lab)

Presentation Slides Presentation_ID463_Watwood.pptx

389 Recent results of experiment IS690: Exploring the excited structure of 11Li through (t,p) reactions at CERN-ISOLDE

Halo nuclei are a group of nuclei characterized by the combination of a low binding energy for their last nucleons and an unusually large spatial extension that deviates from the standard r=r$_oA^{1/3}$ relation. The first empirical observation of this behaviour came from experimental measurements of the interaction cross-section for neutron-rich nuclei, to be more precise, when the scattering cross-section of Lithium isotopes is measured as the number of neutrons gets closer to the dripline the interaction radius deviates from the theoretical predictions $^{11}$Li being the most noticeable case [1]. This discovery was interpreted as a new type of nuclear structure [2], formed by a compact core and an external set of nucleons, this hypothesis was confirmed a few years later in $^{11}$Li break-up experiments [3].
$^{11}$Li can be considered the archetype of a two-neutron type of halo: a three-body system formed by two somehow correlated neutrons loosely bound to the $^{9}$Li ground state (g.s) [4]. Despite having wildly been studied for a long time there are still some questions regarding the structure of $^{11}$Li, while the gs is known to be a mixture of p(59(1)%), s(35(4)%) and d(6(4)%) waves [5], knowledge of higher energy levels is not well established since different reaction studies give different results.$^{11}$Li has no bound excited state. The low-lying continuum spectrum is dominated by broad dipole structures observed in several experiments, while narrower resonances have been proposed between 3.2 and 6.2 MeV. Recent results on the low-lying continuum structure in $^{11}$Li have been obtained from inelastic p and d scattering at TRIUMF [6,7]. The elastic cross sections obtained from both experiments are consistent, however, the inelastic scattering results indicated a resonant state at 0.80(4) MeV, Г=1.15(6) MeV for the proton inelastic scattering channel [7] while this same resonance was characterized to be at 1.03(4) MeV, Г= 0.51(11) MeV in inelastic deuteron scattering [6]. In addition, there is a more relevant question concerning the physics process involved: excitation to resonance or directly to the continuum?
Most experiments exploring the excited structure of $^{11}$Li start from the $^{11}$Li gs nucleus that is promoted to the excited levels. The only exception is the study of the (very complex) $^{14}$C(π$^-$,p+d) reaction [8], whose results were limited by low resolution. The MAGISOL collaboration has performed the IS690 experiment [9] intending to probe the excited structure of $^{11}$Li through an alternate approach: populate directly the excited state of $^{11}$Li using a two-neutron transfer reaction $^{9}$Li(t,p)$^{11}$Li and obtain information of the excited states through the momentum distribution of the residual proton. This experiment acts as a complement to the $^{11}$Li(p,t)$^{9}$Li experiment carried out at TRIUMF [10], additionally, knowledge of the elastic scattering channel can be employed to fix optical potentials in the theoretical models.
IS690 took place at the Scattering Experimental Chamber (SEC) in the HIE-ISOLDE facility at CERN between the 14th and 22nd of October 2024. A post-accelerated 7 MeV/u $^{9}$Li impinged on upon a $^{3}$H-target (3H absorbed in a thin Ti-foil to a ~0.4/1 ratio). The energy of the incoming $^{9}$Li beam was chosen, to facilitate the 2n transfer while reducing the number of additional open channels. An upgraded detection set-up was prepared to detect the emitted protons from the $^{9}$Li(t,p)$^{11}$Li reaction and distinguish it from background reactions, (especially the $^{9}$Li(p,d)$^{10}$Li and elastic channels) while offering optimal angular coverage. This set-up consists of three detector structures: a) five particle telescopes (DSSD+PAD) forming a pentagon around the target (covering 32$^{o}$-83$^{o}$), b) a frontal telescope formed by two S3-CD detectors (covering 6.7$^{o}$-29.4$^{o}$), and c) a backwards S5 detector to detect the backward protons (covering 111$^{o}$-143$^{o}$).
In this contribution, we will provide an overview of the experiment, a summary of the (very recent) data, and our preliminary analysis.

References
1. I. Tanihata et al., Phys. Rev. Lett 55 (1985) 2676.
2. P.G. Hansen and B. Jonson, Europhys. Lett 4 (1987) 409.
3. T.Kobayashi et al., Phys. Rev. Lett 60 (1988) 2599.
4. M.V. Zhukov et al., Phys Rep 231 (1995) 151.
5. J. Tanaka et al., Phys. Lett. B 774 (2017) 268.
6. R. Kanungo et al., Phys. Rev. Lett. 114 (2015) 192502.
7. I. Tanihata and K. Ogata, Eur. Phys. J. A 55 (2019) 239.
8. M.G. Gornov et al., Phys. Rev. Lett. 81 (1998) 766.
9. M.J.G. Borge and J. Cederkäl, Proposal to the ISOLDE and Neutron Time-of-Flight Committee (2021) European organization for nuclear research
10. T. Roger et al., Phys. Rev. C 79 (2009) 031603(R).

Speaker: Daniel Fernández Ruiz (Instituto de Estructura de Materia (IEM-CSIC))

PresentatioN_ID291_Fernandez_Ruiz.pptx

390 Study of the resonance region of 11B using the 10B(d,p)11B reaction

States above particle emission thresholds in $^{11}$B have been of recent interest due to its possible role in $\beta^-$ delayed proton emission from $^{11}$Be. To provide more data on this region, excitation energies from 8.4 to 13.6 MeV were studied using (d,p) reactions on enriched boron targets. A 16-MeV deuteron beam was produced at Florida State University's John D. Fox Superconducting Linear Accelerator. The outgoing protons were deflected and detected using the Super-Enge Split-Pole Spectrograph. Angular distributions for observed states were measured and analyzed with DWBA calculations. The recently observed 11.4-MeV resonance was not observed in this reaction, consistent with the interpretation that it is predominantly a proton resonance. An analogous narrow neutron resonance had been predicted at 11.6 MeV which was also not observed. Upper limits were placed on both states. Shell model calculations using the WBP interaction were perfumed to help interpret the structure of $^{11}$B.

Speaker: Anthony Kuchera (Davidson College)

Presentation_ID303_Kuchera.pdf

391 Gamma-Ray Angular Distribution and Linear Polarization Measurements with GRETINA and the Structure of 25Ne

In the region of neutron-rich nuclei centered around $^{32}$Mg (Z=12, N=20) known as the N=20 Island of Inversion, the conventional neutron magic number N=20 is known to no longer hold. Furthermore, around $^{24}$O (Z=8, N=16) a newly emerging neutron magic number of N=16 has been suggested. Detailed spectroscopy of the excited states in nearby $^{25}$Ne (Z=10, N=15), which abides in this zone of rapidly changing nuclear structure, can therefore provide important data probing nuclear shell evolution and its underlying mechanisms. Here, results from an $^{18}$O beam on $^{9}$Be target fusion evaporation experiment using the Gamma Ray Energy Tracking In-beam Nuclear Array (GRETINA) and the Fragment Mass Analyzer (FMA) at Argonne National Laboratory will be discussed. The angular distribution and linear polarization of the gamma rays emitted following fusion evaporation can be exploited as powerful spectroscopic tools to aid in the determination of the spins and parities of nuclear levels. A variety of types of transitions including mixed dipole-quadrupole transitions with both ΔJ=0 and 1 and stretched quadrupole transitions from the intense fusion evaporation products $^{25}$Mg, $^{25}$Na, and $^{22}$Ne were analyzed to benchmark the performance of GRETINA in angular distribution measurements and as a Compton polarimeter. These techniques were then applied to the observed $^{25}$Ne transitions, helping to clarify its level scheme. Shell model calculations using the FSU Hamiltonian were also performed which successfully reproduce the experimental results.

Speaker: Brenden Longfellow (Lawrence Livermore National Laboratory)

Presentation_ID510_Longfellow.pdf

Parallel Session: 7_Nuclear Structure (3)

Convener: Vandana Nanal (Tata Institute of Fundamental Research)

392 Scalable approaches to the ab initio description of nuclei

Ab initio calculations of atomic nuclei aim at describing their structure and reaction properties starting solely from the basic interactions between nucleons. In the past decade, thanks to developments in many-body theory and in the modelling of nuclear forces, ab initio techniques have steadily progressed and are now able to reach several tens of isotopes up to mass A~100, as well as selected heavy nuclei. The long-term goal is to eventually extend such calculations to the whole nuclear chart, i.e. to several thousands of nuclei up to mass A~300. In this context, one of the main challenges consists in devising computational schemes that can tackle complex, i.e. doubly open-shell, systems and at the same time scale gently with mass number. I will discuss current efforts towards this objective, present recent examples of ab initio calculations of doubly open-shell nuclei and address future perspectives.

Speaker: Vittorio Somà (CEA Saclay)

Presentation_ID698_Soma.pdf

393 Multi-neutron correlations around the neutron drip line

Structure and neutron correlations of nuclei at and beyond the neutron drip line have attracted lots of attention in the last decades [1-3]. They are not only important for advancing our understanding of the structure and interactions of the finite nuclei, and could also bring new insights into the properties of neutron-rich matter that makes up neutron stars. In this talk, I will discuss our recent progress in light neutron-rich nuclei (11Li, 7He, 8He) which are based on experiments performed at the RIKEN RIBF facility.

[1] Siwei Huang and Zaihong Yang, Front. Phys. 11, 1233175 (2023).
[2] F. M. Marqués and J.Carbonell, Eur. Phys. J. A 57, 105(2021) 57.
[3] Y. L.Ye et. al, Nature Reviews Physics (2024).

Speaker: Prof. Zaihong Yang (Peking University)

Presentation_ID196_Yang.pptx

394 Experimental study of neutron-rich 7He and its 3n decay

Multiparticle emission, a novel decay mode discovered in proton-rich and neutron-rich nuclei at and beyond the dripline, represents a frontier in nuclear physics. Impressive experimental progress has been made for nuclei unbound by two or three protons [1]. However, multineutron emission remains largely unexplored on the neutron-rich side due to the very limited capability of multineutron detection. Recently, the 3$n$ emitter $^{27}$O and the first 4$n$ emitter $^{28}$O were observed [2]. The simultaneous detection of these constituent neutrons provides critical insights into the structural properties of these extremely neutron-rich nuclei. Moreover, studying multineutron correlations is crucial for understanding neutron clusters composed purely of neutrons. Low-lying resonance-like structures have been observed in tetraneutron ($^{4}n$) system [3,4], but no distinct peak was found for trineutron ($^{3}n$) system [5]. The existence of these neutron clusters remains controversial between experimental data and theoretical calculations.

The excited state of $^{7}$He is a prospective 3$n$ emitter decaying into $^{4}$He + 3$n$, as indicated by a missing-mass measurement [6]. However, due to the lack of three-neutron detection, the decay mode of $^{7}$He cannot be elucidated. Therefore, a new measurement with improved resolution, low background and 3$n$ detection is essential to solidly establish the structure of $^{7}$He.

We have carried out a new experimental study of $^{7}$He at RIKEN RIBF facility using the quasi-free one-neutron knock out reaction $^{8}$He($p$, $pn$)$^{7}$He. The momentum of the charged fragments was analyzed by the SAMURAI spectrometer and its associated detectors. Taking advantage of the large neutron detector array combining the NeuLAND demonstrator from GSI and the existing NEBULA array, multiple neutrons can be detected. This is the first invariant-mass measurement of the $^{7}$He excited state and its 3$n$ emission. The measured 3$n$ correlations also enable the search for a trineutron resonance.

In this talk, our results will be presented.

[1] M. Pfützner, I. Mukha, S.M. Wang, Two-proton emission and related phenomena, Prog. Part. Nucl. Phys. 132, 104050 (2023).
[2] Y. Kondo et al., First observation of $^{28}$O, Nature 620, 965. (2023).
[3] K. Kisamori et al., Candidate Resonant Tetraneutron State Populated by the $^{4}$He($^{8}$He, $^{8}$Be) Reaction, Phys. Rev. Lett. 116, 052501 (2016).
[4] M. Duer et al., Observation of a correlated free four-neutron system, Nature (London) 606, 678 (2022).
[5] K. Miki et al., Precise Spectroscopy of the 3$n$ and 3$p$ Systems via the $^{3}$H($t$, $^{3}$He)3$n$ and $^{3}$He($^{3}$He, $t$)3$p$ Reactions at Intermediate Energies. Phys. Rev. Lett. 133, 012501 (2024).
[6] A. A. Korsheninnikov et al., Observation of an Excited State in $^{7}$He with Unusual Structure. Phys. Rev. Lett. 82, 3581 (1999).

Speaker: Siwei Huang (Peking University)

Presentation_ID289_Huang.pdf

395 Beta-delayed neutron emission from 8He

8He with 2 protons and 6 neutrons exhibits the most extreme neutron to proton ratio of all known nuclides. It decays by beta-decay with a lifetime of 119ms and a Q-value of 10.65MeV. The decay of 8He is challenging to measure and interpret because the decay produces final states as diverse as 8Li+gamma, 7Li+n, 7Li+n+gamma and triton+alpha+n. The decay mechanism of the decay channel with three hadrons is not known presently.

The decay of 8He represents an irreducible background for reactor antineutrino experiments because it can be produced by cosmic rays impinging on the liquid scintillator used in the neutrino detectors. The correct treatment of this decay is important for developing methods for reducing this cosmogenic background. Existing data on the decay of 8He are insufficient for an adequate treatment of this background in current and planned reactor antineutrino experiments.

We have measured the decay of 8He at the ISOLDE decay station (IDS) at CERN. The IDS is a versatile detection station based around an array of HPGe Clover detectors, which can be supplemented with different auxiliary detectors for electrons, charged hadrons or neutrons. For this experiment a compact array of double-sided silicon strip detectors (DSSDs), plastic detectors with high timing resolution for beta detection and the IDS neutron detector array (INDiE) was used.

The analysis is well advanced. With a digital trace captured for each event in the beta and INDiE detectors, different timing algorithms have been explored to maximize timing resolution for neutron time of flight and consequently energy. As part of the analysis, we have made use of the excellent energy resolution and segmentation of DSSDs to do particle identification of charged particles in coincidence with neutrons by conservation of momentum. Here we have observed neutrons in coincidence with recoiling 7Li nuclei, as well as the alpha-triton-neutron break up of highly excited states of 8Li. In all, this provides complete kinematics identification of all decay channels of 8He with high statistics as well as high spatial and energy resolution.

Speaker: Jeppe Schultz Nielsen (Aarhus University)

Presentation_ID535_Nielsen.pdf

396 Elucidating the isospin mixing of the 8Be 2+ doublet populated via 8B beta-decay

The decay of $^8$B into $^8$Be is of great interest for both nuclear structure and astrophysics. For astrophysics, the decay of $^8$B is the main source of solar neutrinos with energy higher than 2 MeV mainly coming from the intense (88%) beta branch of the $^8$B decay to the 3 MeV state of $^8$Be.

From the nuclear structure point of view, the 2$^+$ ground state of $^8$B is the only well-established proton halo state known. The $\beta^+$/EC decay of this stage could give access to the 2$^+$ doublet at 16.6 and 16.9 MeV in $^8$Be observed in reaction studies more than fifty years ago [1]. These states have dominant configurations as $^7$Li+p and $^7$Be+n, respectively and constitute the highest mixed isospin doublet known [2] (almost 50%), this interpretation aligns well with experimental reaction data, though a direct confirmation remains elusive. The beta decay of $^8$B into $^7$Be offers a valuable tool to probe the isospin composition of this doublet by analyzing the selective contributions from Fermi and Gamow-Teller components. Nonetheless, resolving the feeding to the 2+ doublet poses challenges due to low beta feeding.

Experiment IS633 was performed at the ISOLDE-CERN facility's decay station (IDS), focused on investigating the 2$^+$ doublet of $^8$Be through the beta decay of $^8$B. In this process, $^8$B feeds the excited states of $^8$Be which subsequently break up into two particles or a proton plus $^7$Li, depending on the level fed. Detection of charged particles was achieved through four particle telescopes, each comprising a Double-Sided Silicon Strip Detector (DSSD) stacked with a thick Si-PAD detector. The present data constitute a two-order-of-magnitude improvement in statistics over the preceding benchmark experiment JYFL08 [3] achieving a good separation of the two states for the first time.

In this contribution, a comprehensive description of the IS633 experiment will be presented. The obtained $^8$Be excitation spectrum has been analyzed using a convolution function for the detector response [4] and a four-level R-matrix approach. From it, the feeding to the levels and the deduced fermi and GT transitions to the doublet are extracted. A complementary method based on beta recoil has also been applied. From these two analyses, the isospin mixing of the doublet is determined.

[1] C. P. Browne et al., Phys. Lett. 23 (1966) 371.
[2] P. von Brentano, Phys. Rep. 264 (1996) 57.
[3] O. Kirsebom et al., Phys. Rev. C 83 (2011) 065802.
[4] S. Viñals et al., Eur. Phys. J. A 57 (2021) 49.

Speaker: Prof. Maria J G. Borge (Instituto de Estructura de la Materia, CSIC, Madrid, Spain)

S1_5_borge.pptx

397 Revealing the structures of extremely neutron-rich Helium-9 and Helium-10

Nuclear resonant states far from the stability line provide a stringent test of nuclear forces at extreme isospin asymmetry. Nowadays, it is possible to make ab initio nuclear-structure calculations for very light nuclei. In this talk, I will report on the low-lying resonant states of extremely neutron-rich 9He and 10He populated via the proton induced knockout reactions from 2n-halo nucleus 11Li at ~250 MeV/nucleon. The obtained 9He spectrum shows a clear peak at 1.3 MeV with a width of ~ 1 MeV, which is probably a p-wave resonance. The resonance parameters play a key role to understand the elusive 8He-neutron interactions. The 10He spectrum was obtained from the three-body invariant mass of 8He+2n, with much higher statistics and better sensitivities than previous measurements. The spectrum was compared to the theoretical calculation that combines the coupled-channel three-body model of 11Li and the quasi-free knockout (p, 2p) reaction model. Two low-lying 0+ resonant states of 10He were identified at ~ 1 MeV and at ~2 MeV, which have a [s1/2 s1/2]0+ configuration and a [p1/2 p1/2]0+ configuration, respectively. Unique features of these newly identified states will be discussed.

Speaker: Yelei Sun (Beihang University)

Presentation_ID474_Sun.pdf

398 Two-neutron halo structure of $^{14}$Be studied by its Coulomb breakup

We report on the kinematically complete measurement of the Coulomb breakup of the two-neutron halo nucleus $^{14}$Be on Pb at 220 MeV/nucleon at SAMURAI,RIBF,RIKEN. The previous study [1] showed significantly large E1 excitation of $^{14}$Be at low excitation energies, which was indicative of the revelation of the soft E1 excitation for halo nuclei, while the statistics was very low and the quantitative comparison with theories was not sufficient. The current measurement has significantly higher statistics, and the gamma rays were measured in coincidence to evaluate the core-excited contribution which was missing in the previous work. We will present the energy spectrum of Coulomb breakup cross sections and E1 strength distribution dB(E1)/dEx. The integrated B(E1) strength is applied to assess the spatial dineutron correlation using the non-energy weighted E1 sum rule. The energy spectrum will be compared with the three-body model to discuss the $^{12}$Be-n-n structure, where the valence two-neutron configuration is considered to be a mixture of (1d$_{5/2}$)$^2$, (2s$_{1/2}$)$^2$ and (1p$_{1/2}$)$^2$ due to the N=8 shell gap melting. We discuss the characteristic of dineutron configuration due to such shell structure, which can be different from those in $^6$He [2], $^{11}$Li [3,4] and $^{19}$B [5].

References
[1] M. Labiche, et al., Phys. Rev. Lett. 86, 600 (2001).
[2] Y.L. Sun, et al., Phys. Lett. B 814, 136072 (2021).
[3] T. Nakamura, et al., Phys. Rev. Lett. 96, 252502 (2006).
[4] Y. Kubota, et al., Phys. Rev. Lett. 125, 252501 (2020).
[5] K. J. Cook, et al., Phys. Rev. Lett. 124, 212503 (2020).

Speaker: Yuma Ohsawa (Department of Physics, Institute of Science Tokyo)

Presentation_ID578_Ohsawa.pdf

Parallel Session: 7_Nuclear Structure (4)

Convener: Nadia Tsoneva Larionova

399 New directions for nuclear spectroscopy at the Australian Heavy Ion Accelerator Facility

The shell model has underpinned much of our understanding of nuclear structure for over 70 years. However, many fundamental questions about the nature of atomic nuclei remain unanswered. Obtaining high-quality data to determine key spectroscopic observables, such as electromagnetic transition strengths, and direct measurements of single- and two-nucleon properties form important steps towards attaining a deeper understanding of nuclear structure. In the current ‘era of discovery’ with advanced radioactive-ion-beam facilities, addressing these open questions in systems closer to stability remains a critical task.

The Australian Heavy Ion Accelerator Facility (HIAF) holds a distinguished track record with regards to developing innovative technical infrastructure to explore diverse aspects of pure and applied research in nuclear science. Several equipment upgrades in recent years have enhanced the nuclear-structure research program at HIAF. For decades, the CAESAR array of HPGe and LEPS detectors facilitated extensive research into the nature of nuclear isomers via time-correlated gamma-ray spectroscopy. The CAESAR target chamber has been upgraded with a compact arrangement of charged-particle detectors to facilitate Coulomb-excitation studies. The addition of six ultrafast, lanthanum-bromide detectors and a Pixie-16 digital data acquisition system has also successfully extended the access of experimental measurements to the 10s-of-picoseconds range. To complement this, significant engineering work has also been undertaken to restore the capacity of the HIAF Enge spectrometer to perform nuclear spectroscopy with high-resolution nucleon scattering and transfer reactions. In this presentation, I will discuss results of recent shell-model studies performed at HIAF and future prospects for nucleon-transfer-reaction studies with the new Enge focal-plane detector.

Speaker: Dr AJ Mitchell (Australian National University)

Presentation_ID585_Mitchell-v2.pdf

400 New perspectives for studying nuclear collective states and exotic shapes with the EAGLE gamma spectrometer and the upgraded Recoil Filter Detector at HIL UW

In this presentation, we will discuss the scientific objectives and prospects of the upcoming experimental campaign at the Heavy Ion Laboratory (HIL) in Warsaw. The integration of the modernized Recoil Filter Detector (RFD) with the EAGLE gamma-ray spectrometer [1] offers new opportunities to advance spectroscopic studies of deformed medium-mass nuclei at high spins. This setup is designed to improve sensitivity to gamma rays with high energies, which are typically subject to significant Doppler broadening due to the high recoil velocities of the emitting nuclei. Additionally, the upgraded system will enable the investigation of shape transitions in octupole-deformed thorium nuclei, where gamma-ray spectra are dominated by a large background from competing processes, such as particle evaporation and prompt fission.
The presentation will highlight selected results previously obtained with the RFD detector [2-6], with a particular emphasis on recent technical advancements in the experimental setup, i.e. modernization of its active elements and implementation of a digital signal readout system, which will significantly boost the efficiency of the device, enhance its performance, improve measurement precision, and broaden the scope of future experiments. It will make feasible gamma-ray spectroscopic studies of fast recoiling nuclei in light and medium mass regions as well as very heavy nuclei produced in fusion-evaporation reactions with very low cross-section. The combined use of the RFD and the particle detector DIAMANT [7-8] will improve the EAGLE setup's sensitivity, especially in experiments aimed at high spin studies in exotic nuclei.
References
[1] J. Mierzejewski et al., NIM A, 659, 84 (2011).
[2] W. Męczyński et al., NIM A 580, 1310 (2007).
[3] P. Bednarczyk et al., Eur. Phys. J A 20, 45 (2004).
[4] M. Lach et al., Eur Phys J. A 16, 309 (2003).
[5] D. Rodrigues et al., Phys. Rev C 92, 024323 (2015).
[6] M. Matejska-Minda et al., Phys. Rev C 100, 054330 (2019).
[7] I. Kuti et al., Acta Phys. Pol. B Proc. Suppl. 17, 3-A13 (2024).
[8] J. Sheurer et al., NIM A 385, 501 (1997).

This work is supported by the National Science Centre, Poland under the SONATA BIS-13 Grant Agreement No. 2023/50/E/ST2/00621.

Speaker: Magdalena Matejska-Minda (IFJ PAN Kraków, Poland)

Presentation_ID588_Matejska-Minda.pdf

401 LISA: LIfetime measurements with Solid Active targets

The coexistence of single-particle and collective degrees of freedom in atomic nuclei gives rise to various exotic phenomena. In nuclei with very asymmetric proton-to-neutron ratios, the strong nuclear interaction drives shell evolution which alters the orbital spacing, and in some cases even the ordering present in stable nuclei. In the absence of large gaps between orbitals, nuclei can take on non-spherical shapes and their excitations proceed through coherent and collective motion of many nucleons. Where and how collectivity emerges from the single-particle dynamics of protons and neutrons is an open question in nuclear structure physics that will be addressed with LISA in a unique way.
The aim of the LISA (LIfetime measurements with Solid Active targets) project is to develop a novel method for lifetime measurements in atomic nuclei. Lifetimes probe the collectivity of a nucleus through its electromagnetic transition properties. The experimental approach is based on active solid targets and will dramatically enhance the scope of measurements of excited-state lifetimes and thus transition probabilities achievable in exotic nuclei. Coupled to state-of-the-art gamma-ray tracking detectors such as AGATA, this novel instrument will overcome the present challenges of lifetimes measurements with low-intensity beams of unstable nuclei.
In this talk, I will present an overview of the LISA project and show the potential for future physics experiments at GSI, FAIR, and FRIB.

Speaker: Kathrin Wimmer (GSI)

Presentation_ID13_Wimmer.pdf

402 The Connection Between the 𝛽 decay of 92Rb, the Reactor Antineutrino Anomaly, and the Pygmy Dipole Resonance

The 𝛽-decay of neutron-rich nuclei generated during the fission processes at the cores of nuclear reactors have played a key role in our understanding of neutrino physics and are the source of energy production following reactor shut down known as decay heat. Measurements of the antineutrino flux produced from the beta decay of these nuclei had shown a 6-10% discrepancy between the measured antineutrino flux compared to modern theoretical predictions and has led to intense activity involving multiple approaches to investigate this phenomenon. This Reactor Antineutrino Anomaly (RAA) prompted much excitement as possible evidence for hypothetical sterile neutrinos however recent evidence points towards deficiencies within the model predictions themselves rather than new physics. As the source of these antineutrinos, it is essential that the beta decay of these nuclei is well understood. However, our current understanding of the decay of any of these nuclei is still unsatisfactory.
The 𝛽-decay of 92Rb is one of the main contributors to the reactor high-energy antineutrino spectrum and, consequently, is an important contributor to the RAA. Its decay has been recently studied in Total Absorption Spectroscopy (TAS) and shows significant differences with previous High-Resolution Spectroscopy performed in the early 70s, which can be attributed to the so-called pandemonium effect, when 𝛽 decay branching ratios are poorly measured or even unknown especially for the isotopes that decay with large 𝑄𝛽 values.
We have thus revisited the 𝛽-decay of 92Rb (I = 0-; t1/2 = 4.48(3) s) with the GRIFFIN spectrometer at TRIUMF that consists of up to 16 Compton-supressed HPGe clover detectors. Due to the high intensity radioactive beam of 92Rb of 106 pps and the high efficiency for detecting 𝛾 rays of GRIFFIN we have obtained an unparallel picture of 92Sr with over 180 levels and 850 𝛾-ray transitions up to and beyond the neutron separation energy of ~7.3 MeV, and performed comprehensive 𝛾-ray spectroscopy, including angular correlations to assign spins to the new states.
The decay the I = 0- ground state of 92Rb takes place with a large 𝑄𝛽 value of 8095 keV and populates numerous high-lying 1− levels in 92Sr. These 1- states are situated in the region of the Pygmy Dipole Resonance (PDR) that manifests as an enhancement of 𝐸1 strength below the neutron separation energy, located at the low-energy tail of the Giant Dipole Resonance. The PDR is interpreted as an out-of-phase oscillation between the neutron-skin and an isospin saturated core, however, this remains a matter of debate. The new information of nuclear levels in 92Sr points to the possibility of to investigate the PDR via 𝛽-decay experiments.
The results of this study are also compared to recent TAS experiments and with theoretical shell model calculations and show a great agreement despite of the large density of levels and fragmented decay in 92Sr.

Speaker: Corina Andreoiu (Simon Fraser University)

Andreoiu INDICO.pdf

403 Observation of multi-phonon gamma vibrations in odd-odd nucleus

Neutron-rich nuclei in the A∼100 region show rapid change in shape as a function of both proton and neutron numbers. The shape of some of the even-Z nuclei in this region also exhibits ellipsoidal oscillations, known as gamma vibrations. These gamma-vibrational bands are a measure of triaxiality and gamma softness in this region. Furthermore, the two-phonon gamma-vibrations also provide tests of Pauli principle. As part of a study of the evolution of the structure of even-odd and odd-odd neutron-rich Nb isotopes, the structure of 104Nb was investigated from two complementary methods: i) high statistics triple- and four-fold gamma coincidences from the spontaneous fission of 252Cf using Gammasphere and ii) prompt gamma from the induced fission of the 238U+9Be reaction with isotopic fragment identification using the VAMOS++ and the AGATA spectrometers. Observation of multi-phonon gamma vibrations and shape coexistence of this odd-odd nucleus will be presented.

Speaker: Enhong Wang (Shangdong University)

INPC2025-ehwang.pptx

404 Investigation of excited states in As-76 of interest for double-beta decay

L. Domenichetti, C. Michelagnoli, J. M. Daugas
Institut Laue-Langevin, 71 Av. des Martyrs, 38000 Grenoble, France
M. Scheck, J. Deary, J. Keatings
School of Computing, Engineering, and Physical Sciences, University of the West of Scotland, Paisley, UK
G. Colombi, V. Bildstein, P.E. Garrett
Dept. of Physics, University of Guelph, 50 Stone
Road East, Guelph, ON N1G2W1, Canada
J. Bardak
Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovića 3, 21102 Novi Sad, and GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt
A. Blazhev, A. Esmaylzadeh, J. Fischer, C. Fransen, J. Jolie, C. Lakenbrink, M. Ley, A. Pfeil, F. Spee
Institut für Kernphysik, Universit\"at zu Köln, Köln, Germany
M. Krtička
Charles University, Prague, Czech Republic
D. Patel, P.C. Srivastava
Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, India
J. Suhonen
University of Jyväskylä, Department of Physics, P. O. Box 35 (YFL), FI-40014, Finland

Investigation of excited states in $^{76}$As of interest for $\beta \beta$ decay

In recent years, double-beta decay studies have been conducted both experimentally and theoretically, due to their potential to provide insights into neutrino properties and the conservation of symmetries. While the two-neutrino decay channel is predicted by the Standard Model and has been measured for various nuclei, the neutrino-less channel is yet to be found experimentally and is one of the best-known examples of possible beyond-standard-model physics. A measurement of this process would imply that the neutrino is its own antiparticle and would provide an accurate estimate of its mass, provided that the nuclear matrix element is known. Among many candidates, significant efforts have been made to study, theoretically \cite{Menéndez} and experimentally \cite{Agostini, Šimkovic}, the double-beta decay of $^{76}$Ge to $^{76}$Se. Experiments performed so far have only been able to set a lower limit on the decay lifetimes. The predicted lifetimes and decay rates vary significantly depending on the chosen theoretical description. Theoretically, the wave functions of the $^{76}$Ge ground state and the $^{76}$Se low-lying states play a crucial role. Additionally, theory shows that the structure of the intermediate $^{76}$As nucleus plays a non-negligible role in the decay process \cite{Suhonen}. Therefore, very precise nuclear-physics data are needed to constrain the uncertainty in theoretical predictions. This work aims at studying the structure of $^{76}$As, the intermediate nucleus in the $\beta\beta$ decay of $^{76}$Ge.

The structure of $^{76}$As was investigated in detail through the measurement of the $^{75}$As(n,$\gamma$) reaction using the FIPPS+IFIN array at ILL, in Grenoble. The array consists of 16 HPGe clover detectors, each equipped with anti-Compton shields. The total efficiency of the array was around 3\% at 1408 keV, and its energy resolution was around 5.5 keV at 7 MeV. The setup used a thermal neutron beam from the ILL nuclear reactor, with an intensity of around $10^7\, n/s/cm^2$ \cite{FIPPS}. The experiment was carried out in November 2023 and lasted 14 days. The results of such experiment will be presented. These include 700 new transitions found for states up to 1.5 MeV in excitation energy, the resolution of doublets, and spin assignment of levels up to 500 keV in excitation energy. For the assignment of new decay lines, the coincidence method was used, analyzing both $\gamma\gamma$ matrices and $\gamma\gamma\gamma$ cube projections. To assign spins, the angular correlations of coincident $\gamma$ rays were analyzed. The available information in literature on tentative spin assignments and mixing ratio values was used as a base for the angular correlation analysis. Additionally, the comparison of the experiment results to large-scale Shell Model, RPA and interacting boson-fermion-fermion \cite{Jolie} calculations will be presented. The complexity of the analysis and the difficulty of linking very precise experimental results to theories lead the analysis towards a statistical approach, in complement to the level scheme analysis. Since no analysis of this kind was previously run at FIPPS, a neutron-capture test experiment was performed using the HPGe array in June 2024 using a $^{95}$Mo target. The test aimed to verify the literature values obtained in previous experiments \cite{Milan96Mo}. The same analysis has been applied to $^{76}$As and the results of such analysis will also be presented. To confirm the results found during the ILL experiment, and study states with higher spins, a fusion-evaporation experiment was run at IKP (University of Köln) in October 2024. This experiment exploited the HORUS experimental setup, consisting of 14 Ge detectors, among which six equipped with anti-Compton shields. The performed experiment measured the $\gamma$ rays coming from a $^{76}$Ge(p,n) reaction at 9 MeV on a highly enriched $^{76}$Ge target. The results of the analysis of this experiment will also be presented, and compared to both neutron capture data and recently published fusion-evaporation experimental results \cite{76AsiThemba}.

\bibitem{Menéndez} M. Agostini et al.: \emph{Toward the discovery of matter creation with neutrinoless double-beta decay}, Rev. Mod. Phys. 95, 025002 (2023).

\bibitem{Agostini} M. Agostini et al.: \emph{Results on neutrinoless double-$\beta$ decay of $^{76}$Ge from phase 1 of the GERDA
experiment}, Phys. Rev. Lett. 111, 122503 (2013).

\bibitem{Šimkovic} M. Agostini et al.: \emph{NFinal results of GERDA on the search for neutrinoless double-$\beta$ decay}, Phys. Rev. Lett. 125, 252502 (2020).

\bibitem{Suhonen} J. T. Suhonen: \emph{Value of the axial-vector coupling strength in and decays: A review.}, Frontiers in Physics 5, 55 (2017).

\bibitem{FIPPS} C. Michelagnoli et al.: \emph{FIPPS (FIssion Product Prompt $\gamma$-ray Spectrometer) and its first experimental campaign}, 2018, EPJ Web of Conferences 193.

\bibitem{Jolie} P. Van Isacker, J. Jolie: \emph{Description of vibrational odd-odd nuclei with the interacting boson-fermion-fermion model}, 1989, Nuclear Physics A503.

\bibitem{Milan96Mo} M. Krti\v{c}ka, et al.: \emph{Two-step $\gamma$ cascades following thermal neutron capture in }$^{95}$Mo, 2008, Phys. Rev. C 77.

\bibitem{76AsiThemba} W. Z. Xu, et al. \emph{First observation of band structure in $^{76}$As: Possible chirality and octupole correlations}, 2024, Phys. Rev. C 109.

Speaker: Mr Lorenzo Domenichetti (ILL)

Presentation_Domenichetti_final_024.pdf

Presentation_ID024_Domenichetti.pdf

Parallel Session: 7_Quantum Computing and Artificial Intelligence in Nuclear Physics

Convener: Michael Smith (Stellar Science Solutions LLC)

405 Deep learning for exploring hadron-hadron interactions

In this study, we introduce deep learning technologies for studying hadron-hadron interactions. To extract parameterized hadron interaction potentials from collision experiments, we employ a supervised learning approach using Femtoscopy data. The deep neural networks (DNNs) are trained to learn the inverse mapping from observations to potentials. To link between experiments and first-principles simulations, we further investigate hadronic interactions in Lattice QCD simulations from the HAL QCD method perspective. Using an unsupervised learning approach, we construct a model-free potential function with symmetric DNNs, aiming to learn hadron interactions directly from simulated correlation functions (equal-time Nambu-Bethe-Salpeter amplitudes). On both fronts, deep learning methods show great promise in advancing our understanding of hadron interactions.

Speaker: Lingxiao Wang (RIKEN)

Presentation_ID183_Wang.pdf

406 Adiabatic Perturbation Theory

The growing field of quantum computing shows potential for studying nuclear many-body systems. Unfortunately, current quantum-computational costs do not scale well even for the leading orders of nuclear effective field theories. Our work presents a two-step method for solving hard-to-simulate Hamiltonians. First, we solve the simplest part of the Hamiltonian as a zeroth-order step. This can be done using methods such as the Rodeo Algorithm. Second, we leverage the adiabatic theorem to find perturbative corrections from the easily computable Hamiltonian to a difficult Hamiltonian of interest. This algorithm can be scaled to find increasingly higher order corrections. Used in tandem with methods such as wave function matching, adiabatic perturbation theory can be a powerful tool for solving nuclear many-body problems.

Speaker: Nicholas Cariello (Facility for Rare Isotope Beams)

Presentation_ID390_Cariello.pptx

407 Progress in Machine Learning and Quantum Computing for Nuclear Physics Problems

Machine learning and quantum computing are new tools for scientific research and attracted strong interests in nuclear physics. We applied the Bayesian machine learning for evaluation of noisy, discrepant and incomplete fission yields, which is a practical example of machine learning in nuclear physics [1,2,3], for which it is crucial to merger with physics information in machine learning. The data fusion by machine learning can provide more accurate and useful information [2]. Currently the quantum computing has some initial applications in studies of light nuclei and simple models. We performed quantum computing of a pairing Hamilton at finite temperature on a superconductor quantum computer [4], and applied various methods for error mitigation. We also implemented efficient quantum computing of excited states and constructed low-noise quantum circuit using symmetries. Other progress in machine learning and quantum computing for nuclear physics will also be introduced.

1. Zi-Ao Wang, Junchen Pei, Yue Liu, and Yu Qiang，Bayesian Evaluation of Incomplete Fission Yields， Phys. Rev. Lett. 123, 122501 (2019)
2. Z. A. Wang, J. C. Pei, Y. J. Chen, C. Y. Qiao, F. R. Xu, Z. G. Ge, and N. C. Shu， Bayesian approach to heterogeneous data fusion of imperfect fission yields for augmented evaluations， Phys. Rev. C 106, L021304 (2022)
3. C. Y. Qiao, J. C. Pei, Z. A. Wang, Y. Qiang, Y. J. Chen, N. C. Shu, and Z. G. Ge，Bayesian evaluation of charge yields of fission fragments of 239 U，Phys. Rev. C 103, 034621 (2021)
4. Chongji Jiang and Junchen Pei，Quantum computing of the pairing Hamiltonian at finite temperature, Phys. Rev. C 107, 044308 (2023)

Speaker: Junchen Pei (Peking University)

Presentation_ID59_Pei.pdf

408 Simulating Non-Hermitian Nuclear Systems on Quantum Computers

Quantum resonances are remarkable phenomena observed across various systems, including atomic nuclei. A well-established theoretical method for calculating resonance properties is complex scaling [1], in which we scale the co-ordinate by a complex phase factor $\theta$ i.e $r \to re^{i\theta}$, transforming the Hamiltonian to $H({r}, \theta) = U(\theta)H(r)U(\theta)^{-1}.$ This widely used method requires a large basis set for accurate predictions of complex energy eigenvalue, leading to significant computational challenges. Quantum computers present a promising avenue to address this complexity. Due to the limitations in qubit count and fidelity, hybrid quantum-classical algorithms, such as the Variational Quantum Eigensolver (VQE), are particularly well-suited for noisy intermediate-scale quantum (NISQ) devices [2,3]. However, VQE cannot be directly applied to resonances due to the non-Hermitian nature of the Hamiltonian. To overcome these obstacles, alternate approaches have been proposed in the literature where they embed the non-Hermitian operator into a higher-dimensional unitary matrix, enabling the use of quantum algorithms for direct computation of both real and imaginary components of resonance energies [4].

In the present work, we propose a more efficient algorithm utilizing the spectrum scanning approach for Variational Quantum Algorithm (VQA) [5] and advance the framework to explore the eigenstates of non-Hermitian operators efficiently on a quantum computer. We demonstrate the efficiency of this approach by calculating the resonances of a schematic potential, which is set as a benchmark and extended to nuclear systems, and the results are validated against the traditional diagonalization techniques. Our findings highlight the potential of quantum computing in advancing nuclear physics research, particularly in leveraging noisy intermediate-scale quantum (NISQ) devices for the study of complex quantum systems.

References
1. N. Moiseyev, et al., Molecular Physics 36, 1613 (1978).
2. P. Siwach, P. Arumugam, Phys. Rev. C 104, 034301 (2021).
3. P. Siwach, P. Arumugam, {Phys. Rev. C 105, 064318 (2022).
4. T. Bian, et al., J. Chem. Phys. 154, 194107 (2021).
5. Xu-Dan Xie, et al., Front. Phys. 19, 41202 (2024).

Speaker: Ashutosh Singh (Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, India)

Presentation_ID175_Singh.pptx

409 Application of Machine Learning-Based Enhanced Fault Detection and Predictive Maintenance for Nuclear Reactor Cooling Efficiency

This study discusses the application of artificial intelligence (AI) and machine learning (ML) to address critical challenges in nuclear reactor safety and efficiency, with a focus on fault detection, predictive maintenance, and the optimization of secondary cooling systems. The paper presents an innovative hybrid machine-learning approach for monitoring reactor performance, detecting anomalies, and predicting maintenance needs by combining support vector machines (SVM), K-nearest neighbors (KNN), SARIMA, and LSTM time-series models. Using real-time sensor data, this model enhances fault detection accuracy, supports better decision-making, and reduces operational risks.

Applied to a pressurized water reactor (PWR) model, the approach yielded exceptional results, improving fault classification precision and reliability. The hybrid model achieved a 15% increase in fault detection accuracy and reduced unplanned downtime by 25% compared to traditional methods. This work is unique in integrating advanced machine learning techniques with real-time reactor data to optimize cooling system efficiency, contributing to both operational safety and energy sustainability.

By combining AI-driven predictive maintenance and operational optimization, this research contributes to the development of more reliable and sustainable nuclear reactor systems, improving reactor safety and supporting their long-term viability in the global energy mix.

Speaker: Mr SRI KARNESWARAN SONAIMUTHU (Research Scholar, Indian Institute of Science)

410 Machine Learning for the Automated Analysis of Data from Large-Scale Gamma-Ray Spectrometers

Recent decades have witnessed exponential growth in both the quality and volume of experimental nuclear data, driven by advancements in detector technologies and accelerator capabilities. Gamma-ray spectroscopy, in particular, has benefited from these technological improvements, enabling the collection of increasingly complex datasets from large-scale spectrometers such as GRIFFIN and TIGRESS at TRIUMF, located in Vancouver, Canada. However, the traditional, labor-intensive methods of visually inspecting one- and two-dimensional histograms, time-gating on gamma-gamma coincidences, fitting spectra, and building upon existing level diagrams have struggled to keep pace with the mounting data.

To specifically address the challenges associated with constructing excited-state decay schemes, this research reformulates the construction of level schemes as an inverse optimization problem, taking the gamma-ray singles spectrum and symmetric gamma-gamma coincidence matrices as primary inputs into the algorithm. Using modern software packages for numerical optimization, a machine learning framework is employed to recover directed level-scheme graphs. Furthermore, we investigate hybrid quantum machine learning algorithms and alternative paradigms in high-performance computing to improve scalability and optimization convergence when dealing with higher-dimensional coincidence matrices. Preliminary benchmarking of these frameworks will be presented.

Speaker: Samantha Buck (University of Guelph)

Presentation_351_buck.pdf

10:30 Break

Parallel Session: 8_Hadron Structure and Reactions

Convener: Marc Vanderhaeghen (University Mainz)

411 Deeply Virtual Compton Scattering with CLAS12 at Jefferson Lab

A key step toward a better understanding of the nucleon structure is the study of Generalized Parton Distributions (GPDs). GPDs are nowadays the object of an intense effort of research since they convey an image of the nucleon structure where the longitudinal momentum and the transverse spatial position of the partons inside the nucleon are correlated. Moreover, GPDs give access, via Ji's sum rule, to the contribution of the orbital angular momentum of the quarks to the nucleon spin. Deeply Virtual Compton scattering (DVCS), the electroproduction of a real photon off the nucleon at the quark level, is the golden process directly interpretable in terms of GPDs of the nucleon. The GPDs are accessed in DVCS mainly through the measurements of spin-dependent asymmetries. Combining measurements of asymmetries from DVCS experiments on both the neutron and the proton will allow performing the flavor separation of relevant quark GPDs via linear combinations of proton and neutron GPDs. This talk will mainly focus on recent DVCS measurements from the CLAS12 experiment at Jefferson Lab with the upgraded ~11 GeV CEBAF polarized electron beam. In particular, details on the recent published results of the measurement of Beam Spin Asymmetries from neutron-DVCS will be presented. The impact of the measurement on the extraction of the Compton form factor (CFF) E related to the GPD E of the neutron will be discussed. Further discussion will motivate the foreseen measurements on a transversly polarized proton target aiming to extract the CFF E of the proton.

Speaker: Adam Hobart (IJCLab CNRS-IN2P3)

Presentation_723_HOBALLAH_HOBART.pdf

412 Measurement of the finite transverse single spin asymmetry for very forward neutral pion production in diffractive and non-diffractive processes

The Transverse Single-Spin Asymmetry ($A_{\mathrm{N}}$) provides valuable insights into the motion and structure of quarks and gluons within a nucleon. The RHICf experiment, in collaboration with the STAR experiment, measured neutral particles in very forward ($\eta > 6$) regions in transversely polarized $p+p$ collisions at $\sqrt{s}$ = 510 GeV during the 2017 data-taking period. Previous results from the RHICf Collaboration indicated that the $A_{\mathrm{N}}$ of inclusive neutral pions is non-zero within $\eta > 6$ and $p_{\mathrm{T}, \pi^{0}} < 1$ GeV/$c$. The result also hinted a potentially large contribution from soft processes, such as diffractive reactions. On the other hand, it raises a new question of whether contributions from non-diffractive processes are completely excluded. In this study, we present and compare the $A_{\mathrm{N}}$ for neutral pions in Diffractive-Like and Non-Diffractive-Like events. Event classification is performed based on the particle distribution measured by the STAR detector system. The results highlight the trends in $A_{\mathrm{N}}$ for neutral pions between diffractive and non-diffractive processes.

Speaker: Seunghwan Lee (Sejong University)

Presentation_ID355_Lee.pdf

413 Hard exclusive reactions with baryon number transfer: status and perspectives

Nucleon-to-meson Transition Distribution Amplitudes (TDAs) appear as building blocks in the collinear factorized description of amplitudes for a class of hard exclusive reactions prominent examples being hard exclusive pion electroproduction off a nucleon in the backward region and baryon-antibaryon annihilation into pion and a lepton pair.

We discuss general properties of nucleon-to-meson TDAs and argue that
these non-perturbative objects turn to be a convenient complementary tool to explore the structure of hadrons at the partonic level. We present an overview of hard exclusive reactions admitting a description in terms of TDAs. We discuss the first signals from hard exclusive backward meson electroproduction at JLab and explore further experimental opportunities to access TDAs atJLab, PANDA, J-PARC and EIC.

Speaker: Kirill Semenov-Tyan-Shanskiy (Kyungpook National University, Daegu, Korea)

Presentation_ID483_Semenov-Tyan-Shanskiy.pdf

414 Nucleon axial form factor from lattice QCD

In this talk, I will review the status of lattice QCD calculations
critical for analyzing neutrino interactions with nuclear targets,
focusing on the nucleon axial charge and form factors. The Deep
Underground Neutrino Experiment (DUNE), an upcoming neutrino
oscillation experiment, will benefit significantly from precise
lattice QCD calculations of these quantities. Improved preliminary
results for the nucleon axial charge and form factors will be
presented, along with a discussion of systematic challenges, such as
removing excited-state contributions and obtaining results at the
physical point.

Speaker: Sungwoo Park (Lawrence Livermore National Laboratory)

inpc_sungwoo_v3.pdf

415 Consistency of the pion form factor and unpolarized transverse momentum dependent parton distributions beyond leading twist in the light-front quark model

We investigate the interplay among the pion’s form factor, transverse momentum dependent distributions (TMDs), and parton distribution functions (PDFs) extending our light-front quark model (LFQM) computation based on the Bakamjian-Thomas construction for the two-point function [1,2] to the three-point and four-point functions. Ensuring the four-momentum conservation at the meson-quark vertex from the Bakamjian-Thomas construction, the meson mass is taken consistently as the corresponding invariant meson mass both in the matrix element and the Lorentz factor in our LFQM computation. We achieve the current-component independence in the physical observables such as the pion form factor and delve into the derivation of unpolarized TMDs and PDFs associated with the forward matrix element. We address the challenges posed by twist-4 TMDs and exhibit the fulfillment of the sum rule. Effectively, our LFQM successfully handles the light-front zero modes and offers insights for broader three-point and four-point functions and related observables.

Speaker: Homeoyng Choi (Kyungpook National University)

Presentation_ID307_Choi.pdf

416 Accessing the internal structure of exotic resonances

Exotic resonances were first observed in scattering experiments in 1970s, but the nature of these short-lived resonances still remains debatable. The understanding of such exotic hadrons can provide better insight into the non-perturbative regime of Quantum Chromodynamics (QCD). Resonances such as f$_{0}$(980) and f$_{1}$(1285) challenge the conventional quark model, with their nature remaining uncertain—potentially being tetraquark states or meson-meson molecular states. Similarly, measurements of f$_{2}$(1270), f$_{2}$(1525) and f$_{0}$(1710) productions are sensitive probes to explore gluonic bound states.

Leveraging the advanced particle identification capabilities of the ALICE detector, detailed studies have been conducted on the production of these exotic resonances in proton--proton and proton--nucleus collisions at LHC energies. This contribution will present new measurements of the differential spectra and integrated yields of f$_{0}$(980) and f$_{1}$(1285), along with comparisons to model calculations to verify their internal structure. In addition, this presentation will cover the production of other exotic resonances, such as f$_{2}$(1270), f$_{2}$(1525), and f$_{0}$(1710), which may provide further insights into the nature of Glueballs.

Speaker: Junlee Kim (CERN)

INPC2025_junleekim_v2.pdf

Parallel Session: 8_Hot and Dense Nuclear Matter

Convener: Fuqiang Wang (Purdue University)

417 Heavy flavor under extreme conditions

I will discuss heavy quarks and heavy flavor hadrons at high temperature, high baryon density, strong magnetic field and strong rotation.

Speaker: Pengfei Zhuang (Tsinghua University)

ID308-Zhuang.pptx

418 Lattice calculation of the pairing gap of a unitary fermi gas

The inner crust of a neutron star can be approximated by a dilute gas of strongly interacting non-relativistic two-component fermions, which is characterized by a large negative scattering length and small interaction range. The extreme limit for which both the inverse of the scattering length and the interaction range become zero corresponds to a unitary fermi gas which can be realized from ultra-cold atom experiments in the laboratory. We perform numerical calculations of unitary fermions by employing lattice Monte-Carlo method in the canonical approach. Of particular interest is in the pairing gap, a measure of fermion pairing correlations. We report our results for the pairing gap at zero temperature and critically assess them by comparing to both theoretical and experimental results in the literature.

Speaker: Jong-Wan Lee (Institute for Basic Science (IBS))

unitary_JWL.pdf

419 The spectral reconstruction problem for thermal dilepton and photon production rates from lattice QCD

Thermal dilepton and photon production rates are central probes for understanding QCD at high temperatures. As a consequence there is a strong interest to determine them using lattice QCD calculations. However, this is made difficult as they are related to thermal spectral functions that are not directly accessible through lattice calculations. Instead, they are indirectly obtainable through inverse-Laplace-type transformations of Euclidean-time lattice correlation functions. In this talk our recent results in full QCD with a focus on advancements in spectral reconstruction are presented.

Speaker: Anthony Francis (National Yang Ming Chiao Tung University)

afrancis-inpc25-spf.pdf

420 Extracting the transport coefficients of the QGP with Bayesian inference utilising the latest RHIC and LHC data

The evolution of the strongly interacting quark-gluon plasma (QGP) formed in heavy-ion collisions is modelled with multi-stage models. The models are driven by a large number of parameters that quantify the properties of the medium as well as the initial stage of a heavy-ion collision. The need to find model parameters that give the best description of experimental data imposes a multidimensional optimisation problem. The Bayesian analysis has shown to be successful in constraining the parameter values, and the combined inclusion of LHC Pb$-$Pb 5.02 and 2.76 TeV data, along with additional flow observables, has greatly narrowed down the uncertainties [1].

In this talk, we present our latest study in inferring the transport properties of QGP by including the RHIC Au$-$Au collision data in addition to the LHC data used in the previous studies [1]. Additionally, we now define the centrality separately for all parametrisations instead of using a singular definition for all of them. With the added Au$-$Au data and exclusive centrality calibration, the data now favour smaller values for nucleon width and minimum distance between nucleons. The model calculations with the maximum a posteriori (MAP) parameters show notably better agreement with the data for the anisotropic flow and the identified particle yields than the previous results.

Furthermore, we quantify the sensitivities of newly developed flow observables, Asymmetric Cumulants and Symmetry Plane Correlations, highlighting the importance of measuring independent and sensitive observables. Finally, we explore alternative initial-state models with fewer parameters to improve the estimation and address the current model limitations. This is further studied by comparing the marginal likelihood of the models. These efforts require ongoing advancements in both theoretical frameworks and computational methods.

[1] J.E. Parkkila et al., New constraints for QCD matter from improved Bayesian parameter estimation in heavy-ion collisions at LHC, Phys Lett. B 835, 137485

Speaker: Maxim Virta (University of Jyväskylä)

Presentation_ID670_Virta.pdf

421 Energy dependence of transverse momentum fluctuations in Au–Au collisions from a multiphase transport model

Event-by-event mean transverse momentum fluctuations (⟨pT ⟩) offer a sensitive probe of initial state overlap area and energy density fluctuations in relativistic heavy-ion collisions. We investigate these fluctuations in Au+Au collisions at 3.0–19.6 GeV, focusing on the centrality and energy dependence using an improved multiphase transport (AMPT) model. A power-law dependence of pT cumulants on centrality is observed, consistent with the independent source picture.
Normalized mean transverse momentum ⟨pT⟩ fluctuations and scaled cumulants are conducted, with variances aligning well with the trends observed in experimental data. Using a two-subevents method, short-range correlations are slightly suppressed compared to the standard approach. These findings potentially establish a robust framework for investigating initial state fluctuations across different energies in heavy-ion collisions.

Speaker: Liuyao Zhang (Fudan University (CN))

INPC2025_Liuyaozhang_May302025_v2.pdf

422 Charged-Particle Jet and Jet Quenching Measurement in pp Collisions at $\sqrt{s}$ = 13.6 TeV during LHC Run 3 with ALICE

Jets, collimated showers of particles originating from high-energy parton scatterings, are powerful probes for testing perturbative quantum chromodynamics (pQCD) in large momentum transfer ($Q^2$) events. They may also provide insights into the possible emergence of Quark-Gluon Plasma (QGP) in high-multiplicity events, through jet quenching phenomena, such as hadron-jet correlations.
The ALICE Collaboration commenced Run 3 with upgrades to the Inner Tracking System (ITS2) and the Time Projection Chamber (TPC), both pivotal for probing rare phenomena. The upgraded ITS2 enables higher tracking resolution, while the improvements to the TPC allow for continuous readout, significantly boosting data acquisition. Using these improvements, this work presents key studies: the measurement of inclusive charged-particle jet cross sections and exploration of jet quenching effects using hadron-jet observables in pp collisions at $\sqrt{s} = 13.6\ \mathrm{TeV}$. Using the anti-$k_{\rm T}$ algorithm at midrapidity with background subtraction, these results demonstrate the advanced jet-finding capabilities of ALICE and provide new insights into jet production, fragmentation, and the potential medium effects in high-energy hadron collisions.

Speaker: Joonsuk Bae (Sungkyunkwan University)

Presentation_ID521_Bae.pdf

Parallel Session: 8_New Facilities and Instrumentation

Convener: Prof. Seonho Choi (Seoul National University)

423 Future Prospects of the J-PARC Hadron Experimental Facility

The J-PARC Hadron Experimental Facility was established to investigate the origin and evolution of matter in the universe through experiments utilizing the world’s most intense particle beams. Over the past decade, the facility has made significant advancements in particle and nuclear physics. To further expand its research scope and explore uncharted areas of physics, an extension of the Hadron Experimental Facility is currently under active discussion and planning. This presentation will highlight the achievements to date and the potential contributions of the extended facility to strangeness nuclear physics, hadron physics, and flavor physics.

Speaker: FUMINORI SAKUMA (RIKEN)

085_Sakuma.pdf

085_Sakuma.pptx

424 Study of Heavy Ion Beam Acceleration at J-PARC

This ABSTRACT is prepared for the J-PARC-HI collaboration.

For further development of physics research using high energy heavy ion beams (>10 GeV/u) in the Asia-Pacific region, we are planning to accelerate heavy ion beams at the J-PARC accelerator facility, which consists of a 400 MeV proton linear accelerator (LINAC), a 3 GeV Synchrotron (RCS), and a 30 GeV Main Synchrotron (MR), which can accelerate protons to 30 GeV. When heavy ions are accelerated to the same momentum as protons in this accelerator, even heavy ions such as lead and gold reach 11~12 GeV per nucleon, which is enough to cover the energy range where QGP is expressed.
Unfortunately, LINAC is dedicated to protons and cannot accelerate heavy ions. Therefore, we will prepare an injector dedicated to heavy ions that can accelerate heavy ions to a momentum equivalent to that of 400 MeV protons and inject heavy ions into the RCS.
We came up with the idea of reusing the 500 MeV booster synchrotron of KEK-12GeV-PS, which has already been shut down, to realize this heavy ion injector at a relatively low cost and in a short time. This small accelerator is stored in working condition at KEK Tsukuba, and in combination with an appropriate injector (e.g., a linear accelerator that can accelerate heavy ion beams up to several MeV/u), a heavy ion injector for the RCS can be configured.
In this presentation, the latest status of the heavy-ion acceleration plan, which can be realized at J-PARC as early as possible, will be introduced.

Speaker: Prof. KAZUHIRO TANAKA (IPNS-KEK and ASRC-JAEA)

Presentation＿ID100＿Tanaka.pptx

425 Exploring high-density matter at J-PARC Heavy-Ion Project (J-PARC-HI)

J-PARC is one of the world’s highest-intensity proton accelerators for material and life sciences, neutrino physics, and hadron and nuclear physics in a few ten GeV energy range. J-PARC-HI (J-PARC Heavy-Ion Project) aims to accelerate heavy-ion beams at J-PARC. A new heavy-ion injector consisting of a new heavy-ion linac and a booster ring are required, while heavy-ion beams from the injector can be accelerated in the existing 3-GeV synchrotron (RCS) and 30-GeV synchrotron (MR). The maximum beam rate is expected to reach the world's highest rate of $10^{11}$ Hz, and the energy can vary from 1 to 12 AGeV/c. We will explore QCD phase structures such as the first-order phase boundary, the QCD critical point, and color superconducting phases in a high-baryon density regime in the QCD phase diagram, using various probes such as event-by-event fluctuations, dileptons, collective flow, and two-particle correlations. We also search for various multi-strangeness particles/nuclei and study hadron-hadron interactions including strangeness.
In this talk, we will focus on physics goals, and experimental plans including the staging strategy with a low-intensity injector and an experiment at the existing J-PARC E16 spectrometer (Phase 1), and with a high-intensity injector and an experiment with a new large acceptance spectrometer (Phase 2). We will show the status of the dilepton and hadron measurements in p+A collisions at J-PARC which serves as a baseline experiment for J-PARC-HI. Then, we will show the physics and experime

Speaker: Dr Hiroyuki Sako (Japan Atomic Energy Agency)

INPC2025-J-PARC-HI-final.pdf

INPC2025-J-PARC-HI.pptx

426 Activities from the Korea ALICE group for the development and production of the next generation of silicon tracker

ALICE 3 is the next-generation heavy-ion experiment proposed for LHC Run 5 and 6. Its tracking system will be based on a vertex detector, integrated into a retractable structure inside the beam pipe to achieve the best possible pointing resolution, and a large outer tracker, surrounding the vertex detector and covering a wide range of pseudorapidity. The tracking system will be based on Monolithic Active Pixel Sensor (MAPS) technology. It will leverage the sensor developments carried out for the recently upgraded ALICE Inner Tracking System and the future ALICE ITS3. The total area of the ALICE 3 silicon tracker is a factor of five, larger than the ALICE ITS2, so one of the challenges is a mass chip test and module assembly. R&D has already started to utilize an automatic die-attach machine, which is generally used in the semiconductor packaging industry. This talk will discuss the overall activities of the Korea ALICE group for developing and producing the next generation of silicon trackers.

Speaker: Sanghoon Lim (Pusan National University)

INPC2025_KoALICE_shlim_reduced.pdf

INPC2025_KoALICE_shlim_reduced.pptx

427 Overview of ALICE Inner Tracking System: Current Performance and Future Upgrade

The Inner Tracking System (ITS2) plays a crucial role in tracking and vertex reconstruction in the ALICE experiment at Large Hadron Collider (LHC). The detector consists of seven cylindrical layers equipped with Monolithic Active Pixel Sensors (MAPS), featuring a pixel size of 27 by 29 $\mu$m and sensor thickness of 50-100 $\mu$m. Since the beginning of Run 3 in August 2022, ITS2 has demonstrated stable operation at interaction rates up to 4 MHz in pp and 50 kHz in Pb--Pb collisions, having recorded more than 82 pb$^{-1}$ proton--proton events at $\sqrt{s}$ = 13.6 TeV and 3 nb$^{-1}$ PbPb events at $\sqrt{s_{\rm{NN}}}$ = 5.36 TeV.

In preparation for the LHC Long Shutdown 3 (2026-2029), the ALICE collaboration is developing ITS3, which will replace the three innermost layers of ITS2. This innovative upgrade employs stitching technology in 65 nm CMOS MAPS to produce large-area sensors (approximately 10 x 26 cm$^{2}$). The ultra-thin sensors (50 $\mu$m) can be bent into a half-cylindrical shape, enabling a simplified mechanical structure with only six silicon sensors and light carbon forms. This design achieves a remarkable material budget of 0.07\% X$_{0}$ per layer and reduces the innermost layer radius to 19 mm, projecting a factor of two improvement in tracking performance at low transverse momentum.

This talk will introduce the operational experience and performance of the current ITS2, followed by the design and structure of ITS3, including recent R\&D activities, achievements and expected physics performance improvements.

Speaker: Jiyoung Kim (Inha University)

Presentation_ID263_Kim_ver2-1.pdf

Parallel Session: 8_Nuclear Astrophysics

Convener: Taka Kajino (Beihang University/NAOJ/University of Tokyo)

428 Fine-Features of Nuclear Equation of State from Bayesian Analyses of Future Neutron Star Radius Measurements to 0.1 km Accuracy

To more precisely constrain the Equation of State (EOS) of supradense neutron-rich nuclear matter, future high-precision X-ray and gravitational wave observatories are proposed to measure the radii of neutron stars (NSs) with an accuracy better than about 0.1 km. However, it remains unclear what particular aspects (other than the stiffness generally spoken of in the literature) of the EOS and to what precision they will be better constrained. In this talk, we report results of a recent study [1] within a Bayesian framework using a meta-model EOS [2,3] for NSs. In particular, we infer the posterior probability distribution functions (PDFs) of incompressibility $K_{0}$ and skewness $J_{0}$ of symmetric nuclear matter (SNM) as well as the slope $L$, curvature $K_{\rm{sym}}$, and skewness $J_{\rm{sym}}$ characterizing the density dependence of nuclear symmetry energy $E_{\rm{sym}}(\rho)$, respectively, from mocked NS radii from future measurements with accuracy $\Delta R$ ranging from about 1.0 km to 0.1 km. We found that (1) the $\Delta R$ has little effect on inferring the stiffness of SNM at suprasaturation densities, (2) smaller $\Delta R$ reveals more accurately not only the PDFs but also pairwise correlations among parameters characterizing high-density $E_{\rm{sym}}(\rho)$, (3) a double-peak feature of the PDF($K_{\rm{sym}}$) corresponding to the strong $K_{\rm{sym}}-J_{\rm{sym}}$ and $K_{\rm{sym}}-L$ anti-correlations is revealed when $\Delta R$ is less than about 0.2 km, and the locations of the two peaks are sensitive to the maximum value of $J_{\rm{sym}}$ reflecting the stiffness of $E_{\rm{sym}}(\rho)$ above about 3 times the saturation density $\rho_0$ of SNM, (4) the high-precision radius measurement for canonical NSs is more useful than that for massive ones for constraining the EOS of nucleonic matter around $(2-3)\rho_0$.

References
[1] Bao-An Li et al., Phys. Rev. D 110 (2024) 10, 103040
[2] Nai-Bo Zhang and Bao-An Li, Astrophys. J. 921 (2021) 2, 111
[3] Wen-Jie Xie and Bao-An Li, Astrophys. J. 899 (2020) 1

Speaker: Bao-An Li (Texas A&M University-Commerce)

Presentation_ID499_Li.pdf

429 Photonuclear Reactions by Photon Vortex with Bessel Waves in Astronomical System

Photon vortices are light that carry large orbital angular momentum (OAM) in quantum level　[1]. They can be described by Laguerre-Gaussian or Bessel wavefunctions, which are waves being the eigenstates of the distinct angular momentum along their propagation direction . Unlike plane-wave photons, photon vortices interact differently with materials because their OAM changes the process where they transfer the relatively large angular momentum. In gamma-ray bursts (GRBs), photons in the keV range can become highly polarized due to strong magnetic fields.
We study the process that photon vortices form when electrons have spiral motion in magnetic fields as strong as 10^{12}-10^{13} G. Our results, which considered the Landau quantization, show that that these vortices are likely generated in places with extremely strong fields, such as magnetars or magnetized accretion disks around black holes [2]. Photon vortices can change the total angular momenta of compound nuclei transferred from the photon vortices when they interact with them. This is thought to play an important role in nucleosynthesis in the Universe. Liu et al. [3] found that the amplitudes of low multipole giant resonances become weaker when a photon vortex interacts on a nucleus with a relatively small impact parameter. In real system, however, we need to take the average of the reaction probabilities over the impact parameter.
Our results show that the photon vortices and the photons described by the plane-wave produce similar excitation probabilities [4]. However, the photon vortices allow transitions to states with a wider range of the magnetic quantum numbers, providing a unique perspective on the angular distributions of particle reactions. While these differences may not have a significant impact on stellar nucleosyntheses, they provide valuable insights into the properties of the photon vortices and open up an opportunity for experimental studies with control of the impact parameter to observe states which cannot be easily observed using the plane-wave photons.

[1] L. Allen, et al. Phys. Rev. A 45, 8185 (1992).
[2] T. Maruyama, et al. Phys. Lett. B826. 136779 (2022).
[3] Z.-W, Lu, et al., Phys. Rev. Lett. 131, 202502 (2023).
[4] T. Maruyama, et al. Astro. J. 975, 51 (2024).

Speaker: Tomoyuki Maruyama (Nihon university)

INPC_T.Maruyama.pptx

430 Vortex Creep Heating in Neutron Star Cooling: New Insights into Thermal Evolution of Heavy Neutron Stars

Neutron stars serve as unique natural laboratories for studying nuclear matter under extreme conditions. The temporal evolution of neutron star luminosity and temperature is intricately linked to various physical properties including the equation of state (EoS) of dense nuclear matter, nucleon superfluidity and superconductivity, envelope composition, and magnetic field, allowing us to indirectly probe these properties through observational data. Recent observations (e.g. [1]) have revealed unexpectedly warm temperatures in old neutron stars. The standard cooling scenario, which considers only neutrino emission processes and photon emission during the cooling, predicts much lower temperatures for these old neutron stars, suggesting the presence of additional heating sources. Following previous studies [2] that established vortex creep heating$-$arising from the friction associated with the creep motion of superfluid vortex lines in the neutron star crust$-$as a potential heating mechanism, we extend this framework by incorporating both vortex creep heating and Direct Urca processes in our cooling calculations.

In this work, we implement these mechanisms in our computational framework to explore various evolutionary scenarios using the established relationship between heating luminosity and pulsar rotational evolution. We particularly focus on massive neutron stars where Direct Urca processes become active, a regime not previously investigated in conjunction with vortex creep heating. Through detailed numerical calculations, we systematically investigate how the interplay between heating and cooling mechanisms affects the thermal evolution of neutron stars by varying multiple physical parameters: rotational properties (period $P$, period derivative $\dot{P}$, and initial period $P_0$), EoS (APR, BSk24), pairing gap models for superfluidity and superconductivity, and envelope compositions. In this talk, we will present new evolutionary pathways for massive neutron stars, suggesting that vortex creep heating can significantly modify the rapid cooling traditionally expected from Direct Urca processes.

[1] V. Abramkin et al., Astrophys. J. 924, 128 (2022).
[2] M. Fujiwara et al., Journal of Cosmology and Astroparticle Physics (JCAP) 03, 051 (2024).

Speaker: YOONHAK NAM (Department of Physics, Institute of Science Tokyo)

Presentation_ID122_YOONHAK.pptx

431 Microscopic Investigation of Proton Fluxtubes and Neutron Quantum Vortices in the Neutron Star Core and its Implication to the Pulsar Glitch Phenomenon

Neutron stars are high-density steller objects composed mainly of neutrons and are one of the most important research targets in nuclear physics. Neutron stars are known to exhibit sudden changes of its rotational velocity, known as "pulsar glitches". It has been believed that glitches are mainly caused by dynamic rearrangemenmt of superfluid neutron vortices in the inner crust of neutron stars. However, importance of contributions of the outer core has been recently discussed, and further microscopic investigations of quantum vortices and flux-tubes in the outer core of neutron stars are highly desired.

In this study, we investigate the interaction between quantum vortices of $^3P_2$ superfluid neutrons and flux-tubes of $^1S_0$ superconducting protons in the outer core of neutron stars, based on a successful bosonic theory of superfluid, the Gross-Pitaevskii equation (GPE). In this talk, we will discuss the effects of the interaction between the superfluid quantum vortices and the superconducting magnetic flux-tubes on the $^3P_2$ superfluid quantum vortices and its implication to the mechanism of the pulsar glitch phenomenon.

Speaker: Tatsuhiro HATTORI (Institute of Science Tokyo)

Presentation_ID136_HATTORI.pptx

432 NucleiML : A machine learning tool for finite nuclei properties

The relativistic mean-field (RMF) theory is a versatile framework widely employed in nuclear physics, offering applications that range from calculating finite nuclei properties, such as binding energies and charge radii, to generating the nuclear matter equation of state (EoS) for characterizing neutron star properties, including mass, radius, and tidal deformability. Recent studies have demonstrated that imposing explicit constraints on the finite nuclei properties significantly influences the global behavior of the EoS. However, the computational cost of RMF theory poses challenges for integrating these constraints within a Bayesian analysis framework. In this work, we address this challenge by employing machine learning techniques, specifically neural networks, to develop a predictive model termed NucleiML. This model is trained on an extensive dataset comprising nuclear matter parameters, neutron and proton numbers, and corresponding finite nuclei properties generated by the RMF model. NucleiML demonstrates exceptional accuracy in replicating finite nuclei properties across a wide range of nuclei, closely aligning with RMF theory predictions. Moreover, incorporating NucleiML into Bayesian analyses yields results that are consistent with those obtained using the RMF model, offering a computationally efficient alternative without compromising accuracy.

Speaker: Sarmistha Banik (BITS Pilani, Hyderabad)

Presentation_ID734_banikv2.pdf

Parallel Session: 8_Nuclear Reactions (1)

Convener: Benjamin Kay (Argonne National Laboratory)

433 Pygmy Dipole Resonances within a semiclassical coupled channel model

Nuclei with neutron excess, along and far from the stability valley, shows up a hump, in the excitation region close to the neutron emission threshold, in the isovector dipole strength distribution. This is well separated from the Isovector Giant Dipole Resonance (IVGDR) and with a very small percentage of Energy Weighted Sum Rule (EWSR). This new excitation modes, the so-called Pygmy Dipole Resonance (PDR) has been extensively investigated both experimental and theoretical point of view. Extensive and detailed studies of this mode have been the subject of many experimental and theoretical reviews [1-5].
One of the main characteristic of the mode is its strong isospin mixing which allow the excitation of these states via both isoscalar and isovector probes. Together with the standard electromagnetic ($\gamma, \gamma'$) process, these dipole states have been studied also with isoscalar probes like alpha-particle, $^{17}O$, $^{12}C$ and ($p, p'$) reactions. The use of these different ways of investigation, often on the same nucleus, has brought new informations on the nature and excitation of these low-lying dipole mode.
Therefore, the calculation of the inelastic cross section is of paramount importance for the description the low-lying dipole excitation with isoscalar probes. The use of a semiclassical coupled channel models, based on realistic radial form factors, calculate with a double folding procedure, has revealed a good method to describe the excitation of the PDR. A description of the method and its applications to several nuclear systems will be the content of this contribution.

[1] N. Paar, D. Vretenar, E. Khan, G. Colò, Reports on Progress in Physics 70 (2007) 691–793.
[2] D. Savran, T. Aumann, A. Zilges, Prog. Part. Nucl. Phys. 70 (2013) 210.
[3] A. Bracco, F. Crespi, E. Lanza, Eur Phys. J. A 51 (2015) 99.
[4] A. Bracco, E. G. Lanza, A. Tamii, Prog. Part. Nucl. Phys. 106 (2019) 360.
[5] E. G. Lanza, L. Pellegri, A. Vitturi, M. V. Andrés, Prog. Part. Nucl. Phys. 129 (2023) 104006.

Speaker: Edoardo G. Lanza (INFN - Sezione di Catania)

Lanza-INPC2025-last.pdf

434 Strong nuclear collectivity in the drip-line nucleus $^{11}$Li

The Gamow-Teller Giant Resonance (GTGR) in $^{11}$Li was measured via the $^{11}$Li(p,n)$^{11}$Be charge-exchange reaction at 182 MeV/u in inverse kinematics at the RIKEN Radioactive Isotope Beam Factory. No data has been available for giant resonances studied in drip-line nuclei prior to this work. Specifically, isovector spin-flip giant resonances have only been studied up to (N-Z)/A > 0.25 [1]. Our work explores this uncharted region, focusing on $^{11}$Li ((N-Z)/A = 0.45).
The (p,n) charge-exchange reactions in inverse kinematics, combined with the missing-mass technique, provide an effective method for studying the GTGR in radioactive isotopes across a wide excitation energy range (up to 50 MeV) without the Q-value constraints of β decay [2,3].
The experiment was performed with high luminosity using a combined setup [4] that included the PANDORA low-energy neutron spectrometer [5], the SAMURAI large-acceptance magnetic spectrometer [6], and a thick liquid hydrogen target. PANDORA enabled the detection of recoil neutrons with kinetic energies ranging from 0.1 to 10 MeV, while SAMURAI identified the decay channels of the reaction residues.
In this talk, we present the results of our study. The deduced double differential cross-section up to ~40 MeV, including the observed strong collectivity in the GTGR region, will be reported. We will discuss the seven newly identified decay channels of $^{11}$Be among the 13 observed channels. A comparison of the deduced B(GT) values with those from β-decay studies highlights differences, underscoring the challenges posed by Q-value constraints in β-decay measurements [7-9].
Furthermore, we will discuss the position of the GT peak below the Isobaric Analog State in $^{11}$Li, linking it to the residual spin-isospin interaction and the role of SU(4) symmetry in exotic nuclei.

[1] K. Nakayama, et al., Phys. Lett. B 114, 217 (1982).

[2] M. Sasano et al., Phys. Rev. Lett. 107, 202501 (2011).

[3] J. Yasuda et al., Phys. Rev. Lett. 121, 132501 (2018).

[4] L. Stuhl et al., Nucl. Instr. Meth. B 463, 189 (2020).

[5] L. Stuhl et al., Nucl. Instr. Meth. A 866, 164 (2017).

[6] T. Kobayashi, et al., Nucl. Instr. Meth. B 317, 294 (2013).
[7] R. Raabe et al., Phys. Rev. Lett. 101, 212501 (2008).

[8] M. Madurga et al., Nucl. Phys. A 810, 1 (2008).

[9] M.J.G. Borge et al., Nucl. Phys. A 613 199 (1997).

Speaker: Laszlo Stuhl (CENS, IBS)

Presentation_ID592_Stuhl.pdf

435 Role of higher-order collective excitations on the barrier distribution in back-angle quasi-elastic scattering of massive systems

Back-angle quasi-elastic (QE) scattering provides critical barrier information in massive nuclear reactions leading to the synthesis of superheavy nuclei. The shapes and peaks of QE barrier distributions serve as fingerprints of nuclear structures and reaction dynamics. In this work, we extend the high-accuracy R-matrix method [1] and the finite element method [2-4] to solve the coupled-channels equations for massive systems, which are demonstrated to be more stable than widely used modified Numerov method [5] and allows us to include higher-order vibrational and rotational couplings. Using the reactions 48Ti+208Pb and 51V +248Cm as examples, The calculations shows that higher-order collective excitations significantly smooth the barrier distributions, improving the agreement with experimental data.

References:
[1] Descouvemont, P. (2016). "An R-matrix package for coupled-channel problems in nuclear physics." Computer Physics Communications 200: 199-219.
[2] Wen, P. W., et al. (2020). "Near-barrier heavy-ion fusion: Role of boundary conditions in coupling of channels." Physical Review C 101(1): 014618.
[3] Wen, P. W., et al. (2021). "Potential roots of the deep subbarrier heavy-ion fusion hindrance phenomenon within the sudden approximation approach." Physical Review C 103(5): 054601.
[4] Chuluunbaatar, O., et al. (2022). "KANTBP 3.1: A program for computing energy levels, reflection and transmission matrices, and corresponding wave functions in the coupled-channel and adiabatic approaches." Computer Physics Communications 278: 108397.
[5] Hagino, K., et al. (1999). "A program for coupled-channel calculations with all order couplings for heavy-ion fusion reactions." Computer Physics Communications 123(1–3): 143.

Speaker: Prof. P.W. Wen (China Institute of Atomic Energy)

Presentation_ID86_Wen.pdf

436 Study of low-lying E1 excited states of $^{208}$Pb via the (p,p'$\gamma$) reaction

The Pygmy Dipole Resonance (PDR) is one of the hottest topics in the recent nuclear physics and is generally interpreted as the anti-phase oscillation of the excess neutron skin and core. On the other hand, some theoretical studies suggest that the conventional interpretation may not be complete, and the full description of the PDR is still under debate. For instance, Inakura et al. pointed out that the valence neutrons with low orbital angular momenta play important roles in the strength of the PDR.
In this context, we performed an experimental study of low-lying electric dipole states of $^{208}$Pb via ($p$,$p$'$\gamma$) reactions at $E_p$ = 80 MeV. This experiment is one of the studies undertaken as part of the CAGRA+GR campaign at RCNP, Osaka University. CAGRA stands for Clover Array Gamma-ray spectrometer at RCNP/RIBF for Advanced research, and the array was constituted by 12 clovers borrowed from Argonne National Laboratory in the US, the CCDC/Army Research Laboratory in the US, the Institute of Modern Physics in China, and Tohoku University in Japan. The angular differential cross sections in the range of 3.5-11.5 degrees were measured in coincidence with gamma rays emitted from the inelastically excited states. The non-interacted beam on the target was guided to the wall dump by the newly constructed Grand Raiden forward-mode beam line (GRAF). In the presentation, we discuss the preliminary results of the measurement and other results of the CAGRA+GR campaign collaboration.

Speaker: Nobuyuki Kobayashi (Research Center for Nuclear Physics, Osaka University)

inpc2025_nobu_kobayashi_ver202505230.pptx

437 ISGMR Measurement of Kr isotopes using Active Target CAT-M

The nuclear matter equation of state (EOS) is important not only for understanding the properties and structure of nuclei, but also astrophysical phenomena such as neutron star mergers and supernova explosions. In the field of experimental nuclear physics, efforts have been made to elucidate the EOS by determining the behaviour near saturation density and in symmetric matter by measuring various nuclear reactions or structure.

Recent studies suggest that high-precision, high-accuracy measurements of the isospin-dependent term of incompressibility ($K_\tau$) are important for determining the EOS. The value of $K_\tau$ can be directly derived from the isoscalar giant monopole resonance (ISGMR). Previous studies have obtained $K_\tau = -550 ± 100$ MeV from ISGMR measurements for Sn isotope. However, these measurements were limited to stable nuclei. Furthermore, there have been reports indicating the limitations of $K_\tau$ deriving using the droplet model, such as the splitting of the ISGMR spectrum in deformed nuclei and the so-called “softness,” where theoretical calculations do not match the experimental data. Therefore, it is necessary to measure ISGMR over a wide range of the nuclear chart and to investigate it in more detail, in order to elucidate the fundamental properties of nuclear matter, such as the incompressibility and the nuclear matter EOS.

To enable ISGMR measurements on unstable nuclei using inelastic scattering in inverse kinematics, an active target called CAT-M has been developed. The first experiments were conducted using stable Kr beams at the Heavy Ion Medical Accelerator in Chiba (HIMAC). As a result, we determined the centroid energy of ISGMR to be 17±1 MeV in $^{86}$Kr. In this presentation, we will report on the current status and results of these experiments, and discuss future plans for ISGMR measurements in unstable nuclei.

Speaker: Fumitaka ENDO (RCNP, Osaka University)

Presentation_ID587_ENDO.ppt

Parallel Session: 8_Nuclear Reactions (2)

Convener: Jose Benlliure (Instituto de Física Corpuscular (CSIC - Universitat de Vaència))

438 Emergence of α-cluster correlations probed by α-knockout reactions in Ca isotopes

The emergence of cluster correlations in finite quantum many-body systems is a fundamental topic in nuclear physics. Previous studies have demonstrated the presence of $ \alpha $-clusters in the nuclear surface of $ \mathrm{Sn} $ isotopes [1]. In the present study, we focus on the hypothesized correlation between the $ \alpha $-cluster formation probability and the $ Q_{\alpha} $ value. In the context of $ \alpha $-decay, the Geiger-Nuttall law describes the relationship between the $ Q_{\alpha} $ values and lifetimes, a phenomenon explained by quantum tunneling [2]. However, the direct connection between $ Q_{\alpha} $ values and $ \alpha$-cluster formation remains poorly understood. To address this gap, we investigate the abnormal isotopic dependence of $ Q_{\alpha} $ values in $ \mathrm{Ca} $ isotopes to evaluate their influence on $ \alpha $-cluster formation.

The $ \alpha $-knockout reaction was employed as a method to quantify $ \alpha $-cluster formation probabilities in $ \mathrm{Ca} $ isotopes. The experiment was performed at the RCNP, Osaka University, using a 392-MeV proton beam incident on the $ ^{40,42,44,48}\mathrm{Ca} $ targets. Recoil protons and knocked-out $ \alpha $-particles were analyzed using the Grand Raiden and Large Acceptance Spectrometers, which were optimized for quasi-free $ p $-$ \alpha $ scattering.

The $ \alpha $-cluster separation energy spectra revealed evidence of $ \alpha $-cluster formation in $ \mathrm{Ca} $ nuclei. Further analyses are underway to investigate the isotopic dependence of reaction cross-sections, which will provide insights into amplitudes of $ \alpha $-cluster formation. This work will clarify the relationship between known $ Q_{\alpha} $ values and $ \alpha $-cluster formation.

We will present the details of the experiment, along with preliminary results and ongoing data analyses.

[1] J. Tanaka, Z.H. Yang, S. Typel et al., Science 371, 260 (2021).
[2] H. Geiger and J.M. Nuttall, Philos. Mag. 22, 613 (1911); ibid. 23, 439 (1912).

Speaker: Junki Tanaka (RCNP, Osaka University)

Presentation_ID115_Tanaka.pdf

439 Searching deuteron clusters in mid-heavy nuclei via $^{40, 42, 44, 48}$Ca(p,pd) knockout reaction

Deuteron knockout reactions on calcium isotopes, $^{40,42,44,48}$Ca(p,pd) serve as a valuable probe for understanding nuclear clustering phenomena, particularly deuteron-like correlations within nuclei. These reactions provide a unique opportunity to study the interplay between cluster and shell components in nuclear structure. Recent experimental results have demonstrated the formation of $\alpha$ clusters in dilute neutron-rich tin isotopes, observed via (p,p$\alpha$) knockout reactions [1]. Additionally, the generalized relativistic density functional theory predicts that the clustering of deuterons, tritons, $^{3}$He, and $\alpha$ particles evolves simultaneously on the dilute surface of nuclei [2]. Furthermore, if the clustering mechanisms of deuterons and $\alpha$ particles resemble each other, the neutron-excess dependence of deuteron formation probability is expected to behave similarly [3].

Based on the theoretical and experimental insights mentioned above, a deuteron knockout experiment on calcium isotopes, $^{40,42,44,48}$Ca(p,pd), was carried out by the ONOKORO project group using a 230 MeV proton beam at RCNP, Osaka, Japan. Deuterons from the knockout reaction, acting as clusters, were unambiguously detected at the focal plane of the Large Acceptance Spectrometer for each calcium isotope. Incident protons, following the knockout of clusters, were also detected at the focal plane of the Grand Raiden spectrometer to correctly reconstruct the envisaged events. Results from the analysis of experimental data will be presented in this study.

References
[1] J. Tanaka, Z.H. Yang et al., "Formation of a clusters in dilute neutron-rich matter", Science 371, 260–264 (2021).
[2] S. Typel "Clusters in nuclear matter and the equation of state for astrophysical applications", AIP Conf. Proc. 1520, 68–102 (2013).
[3] T.Uesaka, N.Itagaki, "Nuclear clustering—manifestations of non-uniformity in nuclei", Phil. Trans. R. Soc. A 382 (2024).

Speaker: CheongSoo LEE (IBS)

440 Experimental evidences of the BEC-like states in light nuclei

After the determination of the Bose-condensed structure for the Hoyle state in C-12, continuous experimental works have been devoted to the observation of the BEC-like states in other nuclear systems. We present here a series of reaction-decay experimental works, which provide strong evidences of the 4-alpha condensation-like states in O-16 [1], the alpha + 2n + 2n condensation-like states in neutron-rich nucleus He-8 [2] and the latest preliminary results for the alpha + alpha + 6He condensation-like states in C-14 [to be submitted]. Some background information will also be introduced as recently given in [3, 4].

[1] J. Chen, Y. Ye et al, "New evidence of the Hoyle-like structure in 16O", Sci. Bull. 68, 1119(2023).
[2] Z. Yang, Y. Ye et al, "Observation of the Exotic 0^+_2 Cluster State in 8He", Phys. Rev. Lett. 131, 242501(2023) (Editors' Suggestions).
[3] Y. Ye, X. Yang, H. Sakurai and B. Hu, "Physics of exotic nuclei", nature reviews physics, Published online 25 November 2024 https://doi.org/10.1038/s42254-024-00782-5.
[4] K. Wei, Y. Ye and Z. Yang, "Clustering in nuclei: progress and perspectives", Nucl. Sci. Tech. 35, 216(2024), https://doi.org/10.1007/s41365-024-01588-x

Speaker: Yanlin Ye (Peking University)

Presentation_ID212_Ye.pptx

441 Search for a nuclear Josephson effect in 60Ni+116Sn sub-barrier transfer reactions with the PRISMA+AGATA set-up

Sub-barrier transfer experiments have been recently carried out at LNL in the 60Ni+116Sn system [1,2,3], where the two neutron transfer channel is well Q-value matched. Reaction products have been detected in inverse kinematic and at forward angles with the large solid angle magnetic spectrometer PRISMA, providing high efficiency and resolution. In these studies one follows the behavior of the transfer probabilities by varying the internuclear distance, a method which turned out to be fundamental to probe nucleon-nucleon correlation effects [4,5].
Very recently, the coupling of the AGATA gamma array to PRISMA offered a unique opportunity to study a nuclear (alternating current, AC) Josephson-like effect [6], with Cooper-pair tunneling between superfluid nuclei, whose manifestation has been recently proposed [7] using the 60Ni+116Sn data as a stepping stone. Predictions have been made of a specific gamma strength function associated with the dipole oscillations generated by the, mainly successive, two neutron transfer process. We directly tested for the first time the possible manifestation of this important effect of Cooper pair behavior, observed to date only in condensed matter physics. The experiment has been carried out with very high statistics at a bombarding energy below the Coulomb barrier, corresponding to a distance of closest approach close to the estimated correlation length, exploiting the unique characteristics offered by the PRISMA+AGATA setup in terms of resolution and efficiency. This talk focuses on the ongoing analysis of these new results.

References
[1] D. Montanari et al., Phys. Rev. Lett. 113, 052601 (2014).
[2] D. Montanari et al., Phys. Rev. C 93, 054623 (2016)
[3] L. Corradi et al., Phys. Lett. B 834, 137477 (2022).
[4] L. Corradi, G. Pollarolo, and S. Szilner, J. Phys. G: Nucl. Part. Phys. 36, 113101 (2009).
[5] S. Szilner et. al., Phys. Rev. Lett. 133, 202501 (2024).
[6] B.D. Josephson, Phys. Lett. 1, 251 (1962).
[7] G. Potel, F. Barranco, E. Vigezzi, and R. A. Broglia, Phys. Rev. C 103, L021601 (2021).

Speaker: Giuseppe Andreetta (INFN-LNL and UNIPD)

AndreettaGiuseppe_INPC_forPublication.pdf

442 Extraction of ground state deformation parameters of $^{154}$Sm via fusion barrier distribution

The intrinsic deformation of atomic nuclei has been explored employing a host of experimental techniques and theoretical approaches over the last several decades. Some of the experimental probes are high-energy heavy ion collisions, electron-scattering, muonic X-rays, isotopes shift, Coulomb excitation, neutron-scattering, $\alpha$-scattering, proton scattering, deuteron-scattering, $^3$He-scattering and low-energy heavy ion collisions. It has been found that extraction of unambiguous and accurate value of hexadecapole ($\beta_4$) deformation is rather challenging, compared to the lower-order multipoles $\textit{i.e.}$, quadrupole ($\beta_2$) and octopole ($\beta_3$).

It is well known from studies of low-energy heavy ion-induced reactions that the measured fusion cross sections ($\sigma_{\mathrm{fus}}$) below the barrier are significantly larger in comparison with the prediction of no-coupling model calculations. The observed enhancement can be understood in most cases by considering the couplings between the relative motion and the low-lying collective states of the collision partners and nucleon transfer channels. The couplings lead to a distribution of fusion barrier heights ($\mathcal{D}$) and, thus the shape of the $\mathcal{D}$ contains information about the inherent structure of the participating nuclei. $\mathcal{D}$ for a specific reaction can be derived from precisely measured fusion and differential quasielastic scattering excitation functions, as the two phenomena are complementary to each other due to conservation of incident flux.

In recent years, determination of ground state deformation parameters of $sd$-shell [1, 2], as well as rare earth [3, 4, 5] nuclei, based on either fusion or quasielastic scattering measurements in conjunction with coupled-channels (CC) calculations, has been reported. In this context, a combined analysis of both the fusion and the quasielastic scattering data [6] to extract the deformation parameters of a specific nucleus would be interesting and useful for verifying the robustness of the adopted methodology.

We present here CC analysis, using a modified version of the code ccfull [7], of both fusion and quasielastic scattering excitation functions and $\mathcal{D}$s for the system $^{16}$O+$^{154}$Sm. We note that the $\mathcal{D}$ is more sensitive to minor variations in the reaction parameters compared to the excitation function. The $\mathcal{D}$, which is defined as the double derivative of the $\sigma_{\textrm{fus}}$ times $E$ (energy available in the centre of mass frame of reference) with respect to $E$, is usually derived from measured fusion excitation function using the point difference formula [8]. This method suffers from an ambiguity, related to the energy step size ($\Delta E$), and also results in larger uncertainty in the higher energy end. We have derived the $\mathcal{D}$ from fusion data using a multi-Gaussian analytic recipe proposed by Jiang $\textit{et al.}$ [9], which circumvents these limitations to a large extent. In the CC calculations, $^{16}$O has been treated as inert, while rotational coupling has been considered for $^{154}$Sm including the states $0^{+}$, $2^{+}$, $4^{+}$ and $6^{+}$, for both fusion and quasi-elastic scattering. In both cases, a broad parameter space for $\beta_2$ and $\beta_4$, ranging from $-0.6$ to $+0.6$, has been scanned in fine steps of $0.01$ to obtain the best fit of the $\mathcal{D}$ through $\chi^2$-minimization.

Further, a Bayesian analysis has been performed using a Markov-Chain Monte Carlo (MCMC) framework to quantify the deformation parameters $\beta_2$ and $\beta_4$ along with their uncertainties. Uniform priors have been applied to $\beta_2$ and $\beta_4$ and a Gaussian likelihood function has been used based on the $\chi^2$ statistic. The $\texttt{emcee}$ Python package, which implements the Affine-Invariant MCMC Algorithm [10, 11], has been used to sample the posterior distributions. The fusion data has yielded the values of $\beta_2 = 0.32^{+0.02}_{-0.02}$ and $\beta_4 = 0.06^{+0.02}_{-0.02}$, based on $\mathcal{D}$ with a step size of 1.5 MeV.

For the quasi-elastic cases the optimum values have been found to be $\beta_2 = 0.34^{+11}_{-12}$ and $\beta_4 = 0.31^{+04}_{-04}$. Thus, the values of $\beta_2$ obtained from both fusion and quasielastic data agree quite well. However, determination of $\beta_4$ by this approach appears to be questionable. Similar studies on other nuclei are necessary to verify effectiveness of the method.

The present study demonstrates that the Gaussian analytic method can be useful in deriving the $\mathcal{D}$, which can be corroborated by CC calculations to obtain structural information of the collision partners. It might be rewarding to revisit the wealth of experimental data on heavy ion-induced fusion, that are available in the literature, for similar studies.

It is also important to note here that influence of the $2n$-pickup channel on fusion in the present system has been reported in earlier studies (see $\textit{ e.g.}$, in Ref. [12]). However, the current fusion models are inadequate to account for multi-nucleon transfer (MNT) channels that might affect fusion. Recent studies [13, 14], highlight the limitations of the conventional CC approach in describing low-energy heavy-ion collisions. These limitations suggest that the deformation parameters extracted from fusion and quasielastic scattering data, based on the current theoretical models, may change as deeper understanding of the interplay between MNT channels and fusion is achieved.

$\textbf{Reference}$

[1] Y. K. Gupta $\textit{et al.},$ Phys. Lett. B $\textbf{806}$, 135473 (2020).
[2] Y. K. Gupta $\textit{et al.},$ Phys. Lett. B $\textbf{845}$, 138120 (2023).
[3] Tapan Rajbongshi $\textit{et al.},$ Phys. Rev. C $\textbf{93}$, 054622 (2016).
[4] H. M. Jia $\textit{et al.},$ Phys. Rev. C $\textbf{90}$, 031601(R) (2014).
[5] G. Mohanto $\textit{et al.},$ Eur. Phys. J. A $\textbf{59}$, 234 (2023).
[6] Chandra Kumar and S. Nath, Phys. Lett. B (under review).
[7] K. Hagino $\textit{et al.},$ Comput. Phys. Commun. $\textbf{123}$, 143 (1999).
[8] N. Rowley $\textit{et al.},$ Phys. Lett. B $\textbf{254}$, 25 (1991).
[9] C. L. Jiang and B. P. Kay, Phys. Rev. C $\textbf{105}$, 064601 (2022).
[10] J. Goodman $\textit{et al.}$, Commun. Appl. Math. Comput. Sci. $\textbf{5}$, 65 (2010).
[11] D. Foreman-Mackey $\textit{et al.},$ Publ. Astron. Soc. Pac. $\textbf{125}$, 306 (2013).
[12] J. R. Leigh $\textit{et al.},$ Phys. Rev. C $\textbf{52}$, 3151 (1995).
[13] Kaitlin J. Cook $\textit{et al.},$ Nat. Commun. $\textbf{14}$, 7988 (2023).
[14] G. Colucci $\textit{et al.},$ Phys. Rev. C $\textbf{ 109}$, 064625 (2024).

Speaker: Dr Subir Nath (Inter University Accelerator Centre)

Presentation_ID436_Kumar.pdf

443 Model bias and parameter optimisation with the example of INCL/ABLA

The accuracy (the bias) and precision (the uncertainties) of high-energy spallation models is a key issue for the design and development of new applications and experiments. In the case of the combination of the IntraNuclear Cascade model of Liège (INCL) [1, 2] and the Ablation model (ABLA) [3, 4], we address the problem through two orthogonal approaches, both based on a Bayesian framework. In the framework of the joined project NURBS, shared between the Swiss National Science Foundation (SNF) and the French National Agency for Research (ANR), we developed an approach to optimise the internal parameter of the model [5] and, on the other hand, we developed a method to estimate the bias of the model [6]. The first approach improve the accuracy and the second quantify the accuracy and the precision of model combination. This will be used to study observable ranging from the double differential neutron production to the hypernuclei fission cross section.

References
[1] A. Boudard et al., Phys. Rev. C 87, 014606 (2013). https://link.aps.org/doi/10.1103/PhysRevC.87.014606
[2] D. Mancusi et al., Phys. Rev. C 90, 054602 (2014). https://link.aps.org/doi/10.1103/PhysRevC.90.054602
[3] J. L. Rodrı́guez-Sánchez et al., Phys. Rev. C 105, 014623 (2022). https://doi.org/10.1103/PhysRevC.105.014623
[4] J. L. Rodrı́guez-Sánchez et al., Phys. Rev. Lett. 130, 132501 (2023). https://doi.org/10.1103/PhysRevLett.130.132501
[5] J. Hirtz et al., EPJ A 60, 149 (2024). https://doi.org/10.1140/epja/s10050-024-01370-y
[6] G. Schnabel, EPJ Nuclear Sci. Technol. 4, 33 (2018). https://doi.org/10.1051/epjn/2018013

Speaker: jason Hirtz (CEA Saclay)

Presentation_ID497_Hirtz.pdf

Parallel Session: 8_Nuclear Structure (1)

Convener: Hiroshi Watanabe (Center for Exotic Nuclear Studies)

444 Manifestation of the Berry phase in the atomic nucleus $^{213}$Pb

I will present some of our later results on the $^{213}$Pb neutron-rich nucleus [1] studied using the unique availability of a primary 1 GeV $A$ $^{238}$U beam and of the FRS-RISING setup at GSI. The products of the uranium fragmentation were separated in mass and atomic number and then implanted for isomer decay $\gamma$-ray spectroscopy. A level scheme from the decay of the $21/2^+$ isomer, based on $\gamma$ intensities, $\gamma$-$\gamma$ coincidences and state lifetimes was built up and the $E2$ transition probabilities from the $21/2^+$ isomer to two low-lying $17/2^+$ levels were also deduced.

This experimental data has evidenced one of the best examples of a semi-magic nucleus with a half-filled isolated single-j shell where seniority selection rules are obeyed to a very good approximation. In the most simple shell-model approach $^{213}$Pb can be described as five neutrons in the $1{\rm g}_{9/2}$ orbital on top of the $^{208}$Pb core. Large scale shell-model calculations in the full valence space beyond $^{208}$Pb confirm that although the $1{\rm g}_{9/2}$ orbital is not isolated in energy, it is found to carry the dominant component in the wave function of the low-energy states. The experimental level scheme and the reduced transition probabilities are in good agreement with the theoretical description that predicts the existence of two $17/2^+$ levels of a very different nature: one with seniority $\upsilon=3$, while the other with $\upsilon=5$. The absence of mixing between the two $17/2^+$ states follows from the self-conjugate character of $^{213}$Pb, where the particle-hole transformation defines an observable Berry phase that leads to the conservation of seniority for most but not all states in this nucleus.

The Berry phase [2], which is a gauge-invariant geometrical phase accumulated by the wavefunction along a closed path, is a class of observables that are not associated with any operator. It is a key feature in quantum-mechanical systems, that has far reaching consequences, and has been found in many fields of physics since its postulation in the eighties. In the atomic self-conjugate nucleus $^{213}$Pb, the quantized Berry phase is evidenced by the conservation of seniority under the particle-hole conjugation transformation. In atomic nuclei no experimental signature of the Berry phase was reported up to now.

[1] J.J. Valiente-Dob\’on et al., Physics Letters B 816, 136183 (2021).
[2] M. V. Berry, Proc. Roy. Soc. A392, 45 (1984).

Speaker: Jose Javier Valiente Dobon (CSIC-IFIC)

Presentation_ID7227_Valiente.pptx

445 Decay spectroscopy of a high-spin long-lived isomer in 187Ta using KISS facility

$^{187}$Ta (Z = 73, N = 114) is located in the neutron-rich A $\approx$ 190 region where a prolate-to-oblate shape transition via triaxial softness is predicited to take place. Using high mass resolving power at the Experimental Storage Ring at GSI, the ground state and two long-lived isomers in $^{187}$Ta were previously identified with their masses, which were translated into excitation energies of 1789(13) keV and 2933(14) keV for the first and second isomers, respectively [1]. In our work, the $^{187}$Ta isomers have been populated by a multi-nucleon transfer reaction with a $^{136}$Xe primary beam incident on a natural tungsten target using the KEK Isotope Separation System (KISS) [2] at RIKEN. A preceding analysis on the first isomer and a rotational band to which the isomer decays revealed that the isomer has K$^{\pi}$ = (25/2$^-$) and axial symmetry is slightly violated in this nucleus [3]. In this presentation, we will focus on new experimental findings obtained for the second isomer, such as the internal $\gamma$- and external $\beta$-decay branches and a neutral-atom half-life of 136(24) s [4]. The spin-parity assignment constrained by the evaluated hindrances for K-forbidden transitions and its interpretation based on configuration-constrained potential-energy surface calculations will be discussed.

Reference:
[1] M. W. Reed et al., Phys. Rev. Lett. 105(2010) 172501; Phys. Rev. C 86(2012) 054321.
[2] Y. Hirayama et al., Nucl. Inst. Meth. B353, 4(2015), and B412, 11(2017).
[3] P. M. Walker et al., Phys. Rev. Lett. 125(2020) 192505.
[4] J. L. Chen et al., Phys. Rev. C (accepted for publication).

Speaker: Jiulong Chen (Beihang University)

JLC_INPC2025.pdf

446 Evolution of High-spin Structure in Neutron-rich Au Isotopes near N=126 Shell Closure

Neutron-rich nuclei around A ≈ 200, near the doubly magic 208Pb, are particularly intriguing due to their transitional nature. Both collective and intrinsic degrees of freedom likely play a critical role in determining their level structure. Furthermore, experimental studies of nuclei near closed shells provide an excellent opportunity to test shell model predictions based on effective nuclear interactions. While substantial structural information is available for Pt (Z=78) and Hg (Z=80) to Pb(Z=82) isotopes [1], this is not the case for the high-spin structure of neutron-rich A~200 for the odd Z case, e.g. Au (Z=79) isotopes. To investigate the evolution of collectivity below the N=126 shell closure, the high-spin structure of odd-even and odd-odd $^{195-202}$Au isotopes has been studied using prompt-delayed $\gamma$-ray spectroscopy.
The neutron-rich N~126 nuclei in the southwest region of $^{208}$Pb were produced using multi-nucleon transfer reactions between $^{136}$Xe beam (7 MeV/u) and $^{198}$Pt target at GANIL. The Projectile-Like Fragments (PLFs) were fully identified by VAMOS++ spectrometer [2]. The corresponding Target-Like Fragments (TLFs) (N~126), were selected based on the isotopically identified PLFs and excitation energy of the fragments. The prompt $\gamma$ rays of the fragments were measured by the state-of-the-art HPGe tracking array, AGATA [3]. Several new methods for characterizing of TLFs have been used. CATLIFE, a ToF spectrometer coupled with EXOGAM HPGe detector array, is utilized to measure the delayed $\gamma$ rays of TLFs and obtain their mass number before the neutron evaporation [4]. For the analysis of the VAMOS++ data, a new calibration method, based on supervised learning techniques, for the kinetic energy was developed [5]. The new method improved the identification of ion charge state, especially at energies around the Bragg peak region.
In this contribution we will report on our recent results [6] where a dip like structure at N=119, a possible evidence for locally enhanced collectivity near the N=126 shell closure. This is shown from the evolution of the measured low-lying states above the isomers in Au isotopes. These levels in Au reflects the structure inherited from the corresponding states of the neighboring Hg core and is maintained consistently throughout the long isotopic chain.
Other experimental findings will also be presented. One is the disappearance of odd-j mirror band in the level scheme of odd-odd Au isotopes for N$\geq$117. New isomers in $^{199}$Au and $^{201}$Au have been identified with T$_{1/2}$ = 140(20) 𝜇s and 15.2(29) 𝜇s, respectively. The observed features are interpreted based on large-scale shell model calculations.

[1] NNDC — National Nuclear Data Center — https : / / www.nndc.bnl.gov.
[2] M. Rejmund et al. Nucl. Instrum. Methods. A646 (2011).
[3] S. Akkoyun et al. Nucl. Instrum. Methods. A668 (2012).
[4] Y. Son et al. Nucl. Instrum. Methods. B540 (2023).
[5] Y. Cho et al. Nucl. Instrum. Methods. B541 (2023)
[6] Y. Cho, Phd thesis Seoul National University (2025)

Speaker: Youngju Cho (Seoul National University)

Presentation_ID549_Cho.pdf

447 Nuclear spectroscopy of neutron-rich Ta, W, Re at KISS

The neutron-rich transitional nuclei with $A\sim190$ demonstrate a shape transition from well-deformed to $\gamma$-soft structures with increasing neutron number [1]. Some of the nuclei in this region have been well studied in previous experimental investigations of nuclear masses, nuclear structure, and transitions, as summarized in a recent review paper [2].
Recently, the use of multi-nucleon transfer reactions at KEK Isotope Separation System (KISS) [3] in RIKEN have enabled us to expand multi-faceted nuclear spectroscopy in this region via decay spectroscopy of $^{187}$Ta [4] and mass spectroscopy of $^{189}$W, $^{192}$Re using a MRTOF-MS [5]. In this work, the decay scheme of $^{187}$Ta has been newly established, connecting previously known $\gamma$-transitions in $^{187}$W. The masses of $^{189}$W and $^{192}$Re were successfully measured, and the trend of the two-neutron separation energies for neutron-rich W and Re isotopes was interpreted based on DFT calculations, suggesting that shape transitions from prolate deformation begin at $N = 116$ and $N = 117$ in the W and Re isotopic chains, respectively, consistent with previous studies.
In this talk, we will introduce the details of the experiments and discuss the above experimental results.

References:
[1] R. F. Casten, Nucl. Phys. A 443, 1 (1985).
[2] G. G. Kiss and Z. Podolyák, Eur. Phys. J. A 60, 175 (2024).
[3] Y. Hirayama et al., Nucl. Inst. Meth. B 353, 4 (2015), and B 412, 11 (2017).
[4] M. Mukai et al., Phys. Rev. C 105, 032331 (2022).
[5] M. Mukai et al., Phys. Rev. C, accepted for publication.

Speaker: Momo Mukai (WNSC, IPNS, KEK)

Presentation_ID368_Mukai.pdf

Presentation_ID368_Mukai.pptx

448 Shape-coexistence near the neutron mid-shell nucleus Pb-190 studied in in-beam experiments

Shape coexistence is a phenomenon where multiple shapes occur within the same nucleus and has been proposed to exist in all nuclei [1]. In particular, neutron-deficient Pb nuclei near the N=104 mid-shell provide fruitful ground for investigating this phenomenon. Notably, $^{186}$Pb, $^{188}$Pb and $^{190}$Pb isotopes exhibit three distinct shapes near their ground states [2-7]. In the shell-model picture, these three shapes are associated with 0p-0h (spherical), 2p-2h (oblate) and 4p-4h (prolate) multiproton-multihole configuration [8].

Recently, we have performed two complementary in-beam experiments to asses competing shapes in the $^{190}$Pb nucleus: one utilised a simultaneous in-beam γ-ray and conversion electron spectrometry, and the other employed plunger device for lifetime measurements of excited states. These experiments allowed for the reassigning of the yrast band with a predominantly oblate shape, confirmed predominantly prolate shape assignment for the non-yrast band, and discovered a candidate for the spherical 2$^+$ state. These findings highlight the power of combining these two distinct methods to enhance our understanding on shape coexistence.

This presentation will cover the latest in-beam experiments in this region performed at the Accelerator Laboratory in Jyväskylä, Finland [3,6,7].

[1] Heyde, K. & Wood, J. L. Phys. Scr. 91, 083008 (2016)
[2] Andreyev, A. N. et al. Nature 405, 430–433 (2000)
[3] Ojala, J. et al. Commun. Phys. 5, 213 (2022)
[4] Bijnens, N. et al. Z. Phys. A, 356, 1 (1999)
[5] Dracoulis, G. et al. Phys. Rev C, 69, 054318 (2004)
[6] Montes-Plaza, A. et al. Comm.phys. 8, 8 (2025)
[7] Papadakis, P. et al. Phys. Lett. B 858, 139048 (2024)
[8] Heyde, K. & Wood, J. L. Rev. Mod. Phys. 83, 1467–1521 (2011).

Speaker: Joonas Ojala (University of Jyväskylä)

Presentation_ID536_Ojala.pdf

Parallel Session: 8_Nuclear Structure (2)

Convener: Kota Yanase (RIKEN)

449 Unravelling the layers of future element discovery with SHREC

The heaviest elements on the periodic table ($Z = 114-118$) were first produced using beams of $^{48}$Ca in fusion-evaporation reactions with actinide targets. Since no target material with $Z > 98$ is available in sufficient quantities, a beam with higher $Z$ is required for new element discovery campaigns. At the 88-inch cyclotron facility of Lawrence Berkeley National Laboratory significant upgrades are underway in preparation for a potential element 120 search campaign using the $^{50}$Ti + $^{249}$Cf reaction and the Berkeley Gas-filled Separator (BGS). Over the past year, the ion source team has developed novel induction oven technology that has allowed for the production of $^{50}$Ti beams with on-target intensities in excess of 1.5p$\mu$A. At the BGS focal plane a new detector array for SuperHeavy RECoils (SHREC) has been implemented and commissioned alongside a modern digital data acquisition system. A significant upgrade to the BGS target area is also currently in development to better facilitate future experiments that use actinide targets such as $^{249}$Cf. In this presentation I will give an overview of these recent upgrades as we prepare to search for a new element with SHREC at the BGS and I will highlight the recent successful observation of $^{290}$Lv which was produced using a beam of $^{50}$Ti for the first time.

Speaker: Rodney Orford (Lawrence Berkeley National Laboratory)

450 First Fully Microscopic Description of Fission with Three Collective Dimensions

Nuclear fission occurs when a nucleus splits into smaller nuclei, releasing a significant amount of energy. Although nuclear fission was discovered more than seventy years ago, accurately predicting its behavior based on the basic constituents of nuclei remains challenging due to the extremely high dimensionality of the quantum space involving numerous particles. Hence, an approximation scheme is necessary to describe fissioning systems and simplify their complex nature into a more manageable form. The nuclear density functional theory is such a framework that can predict nuclear properties for most elements on the nuclear chart. However, it is still limited by computational constraints. As a result, most fully microscopic implementations have only considered two collective degrees of freedom, such as the elongation and the asymmetry of the fissioning system. Recently, we enhanced this approach by incorporating a third degree of freedom. This presentation explores our improvements to the theory and discusses the results we obtained with it.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.
Lawrence Livermore National Security, LLC.

Speaker: Marc Verriere (Lawrence Livermore National Laboratory)

Presentation_ID724_Verriere.pdf

451 How far does the area of superheavy nuclei extend? -Limit of existence of nuclei estimated from decay modes from a mass formula-

Decay modes and total half-lives of nuclei in the entire region of nuclear chart will be discussed with the use of the spherical-basis method [1]. This method is developed for calculation of ground-state nuclear masses, known as the KTUY mass model [2], and of potential energy surface (including fission barrier height) against nuclear deformations [3]. The global properties of each nuclear decay as alpha- decay [4], beta-decay [5,6], proton emission, and fission [3] will be presented. In the calculation, the existence of ‘Island of superheavy nuclei’ around Z=114 (or 126), and N=184 on the nuclear chart, and ‘Peninsula of superheavy nuclei along N=228, and beyond can be estimated [7]. The appearance of these landscapes is due to the shell closure of (spherical) single-particle levels of nuclei there [8]. We will discuss the limit of existence of nuclei estimated from decay modes with a mass formula, and show the entire landscape of nuclear chart.

[1] H. Koura, M. Uno, T. Tachibana, M. Yamada, Nucl. Phys. A. 674 47, (2000)
[2] H. Koura, T. Tachibana, M. Uno, M. Yamada, Progr. Theor. Phys. 113 305, (2005)
[3] H. Koura, Prog. Theor. Exp. Phys. 2014 113D02-1-10, (2014)
[4] H. Koura, J. Nucl. Sci. Technol., 49 816-823 (2012)
[5] H. Koura and S. Chiba, Phys. Rev. C 95, 064304 (2017)
[6] F. Endo and H. Koura, Phys. Rev. C 99, 034303 (2019)
[7] H. Koura, Nihonium -Physics in superheavy elements and superheavy nuclei-, Kyoritsu Shuppann Co., Ltd., Jun. 2021, (ISBN: 9784320035447) (in Japanese)
[8] H. Koura and S. Chiba, J. Phys. Soc. Jpn. 82, 014201 (2013)

Speaker: Hiroyuki Koura (Advanced Science Research Center, Japan Atomic Energy Agency)

Presentation_ID425_Koura.pdf

452 The spontaneous fission of heavy nuclei. Open questions

The new experimental data about spontaneous fission was obtained for a range of heavy nuclei. Short-lived isotopes were synthesised in complete fusion and multi-nucleon transfer reactions on velocity filter SHELS. The modern SFiNx system and planned SHE Fission TPC detector will be presented.

Speaker: Andrey Isaev (FLNR JINR)

453 Low-energy spectra of nobelium isotopes

The low-energy multipole spectrum in isotopes 250-260No is investigated in the framework of fully self-consistent Quasiparticle-Random-Phase-Approximation (QRPA) method with Skyrme forces (SLy6, SkM* and SVbas) is applied. The main attention is paid to nuclei 252No and 254No, where we have most of the experimental spectroscopic information [3,4]. In addition to low-energy one-phonon collective states (lm=20,22,30,31,32,43) and K-isomers (Kπ = 2-,8-,3+). In general, a good agreement with the experimental data is obtained. It is shown that, in the chain 250−260No, features of 252No and 254No exhibit essential irregularities caused by a shell gap in the neutron single-particle spectra and corresponding break of the neutron pairing. The low-energy pairing-vibrational Kπ = 0+ state is predicted in 254No.
[1] P.-G. Reinhard, B. Schuetrumpf, and J. A. Maruhn, Comp. Phys. Commun. 258, 107603 (2021).
[2] A. Repko, J. Kvasil, V.O. Nesterenko and P.-G. Reinhard, arXiv:1510.01248[nucl-th].
[3] R.-D. Herzberg and P.T. Greenlees, Prog. Part. Nucl. Phys. 61, 674 (2008).
[4] R.-D. Herzberg, arXiv:2309.10468[nucl-ex].
[5] F.L. Bello Garrote et all, Phys. Lett. B834, 137479 (2022).

Speaker: Mariia Mardyban (BLTP, JINR)

252-254No_Mardyban.pdf

252-254No_Mardyban.pptx

Parallel Session: 8_Nuclear Structure (3)

Convener: Takayuki Miyagi (University of Tsukuba)

454 Investigating Nuclear Structure using MR-ToF devices at CERN

Nuclear observables, such as binding energies, electromagnetic moments, and charge radii, arise from various effects that govern nuclear properties. Studying these properties often requires fast measurement techniques due to the short half-lives of the isotopes of interest. In recent years, the Multi-Reflection Time-of-Flight (MR-ToF) device has become a key instrument in the investigation of nuclear binding energies of isotopes with half-lives in the order of a few tens of milliseconds and is now also used to perform colinear laser fluorescence spectroscopy. In this contribution, we will explore the latest results of the MR-ToF devices at CERN-ISOLDE, including precision mass measurements and ion beam composition studies at ISOLTRAP, colinear laser spectroscopy at MIRACLS, and plans for employing a high-energy MR-ToF device for the antiproton-unstable matter annihilation experiment PUMA.

Speaker: Lukas Nies (CERN)

Presentation_ID341_NIES.pptx

455 Present status on high-precision atomic mass measurements using MRTOF-MS at RIBF

One of the pillars for the study of exotic nuclides and astrophysical processes is the precise knowledge of the nuclear binding energy, which is directly and model-independently deduced from atomic-mass data. Tackling the increasing challenge to determine the mass of isotopes having low production yields and short half-lives, multi-reflection time-of-flight (MRTOF) mass spectrometry has grown from an initially rarely-used technology to the world’s most commonly-used method for measurements with a relative mass precision down to $\delta m/m = 10^{−8}$. This technology has been developed at RIKEN’s RIBF facility for about two decades in combination with gas-filled ion catchers for low-energy access of isotopes produced by the in-flight method.
In the recent past, three independent systems operating at different access points at RIBF, have provided substantial data in the medium- and heavy-mass region of the nuclear chart, reaching out to the superheavy nuclides. Recent achievements like high mass resolving power [1] followed by installations of α/β-TOF detectors [2] and in-MRTOF ion selection have tremendously increased the selectivity of the systems, allowing for background-free identification of the rarest isotopes.
In this contribution, I will give a short overview about the success of MRTOF atomic mass measurements using BigRIPS in the recent past [3-5], and further focus on new achievements from 2024. An outlook will be given for instrumentation, with a view to new MRTOF systems, and the combination with established methods for decay spectroscopy.

References:
[1] M. Rosenbusch et al., Nucl. Instrum. Meth. A 1047, 167824 (2023).
[2] T. Niwase et al., Theo. Exp. Phys. 2023(3), 031H01 (2023).
[3] S. Iimura et al., Phys. Rev. Lett. 130, 012501 (2023).
[4] D. S. Hou et al., Phys. Rev. C 108, 054312 (2023).
[5] W. Xian, S. Chen et al., Phys. Rev. C. 109, 035804 (2023).

Speaker: M. Rosenbusch (RIKEN Nishina Center)

INPC_Korea_talk_nobkp.pdf

456 High-precision direct mass measurement of trans-uranium isotopes using the MRTOF systems at RIKEN/KEK

The multi-reflection time-of-flight mass spectrograph (MRTOF-MS) [1] is one of the tools for high-precision direct mass measurement of the nuclides. We have operated several MRTOFs in the RIKEN RIBF facility. The SHE-Mass facility, which couples MRTOF-MS + α-TOF detector with the gas-filled recoil ion separator GARIS-II [2], is working on the mass measurement of heavy and superheavy nuclides produced in fusion reactions. The MRTOF-MS connected to the KEK isotope separation system KISS [3] allows the mass measurement of neutron-rich nuclides produced via multi-nucleon transfer reaction.
In the SHE-Mass facility, we have measured the mass of dubnium isotopes (Z=105) produced by the fusion reaction[4], which are the heaviest nuclides directly measured to present. Also, in the KISS setup, we have performed the first investigation of the MNT actinide products formed in the $^{238}$U + $^{198}$Pt system. We have succeeded in the direct mass measurements of nineteen neutron-rich actinide nuclides spanning from protactinium to plutonium, including the first identification of a new uranium isotope ($^{241}$U) since the 1970s [5].
In this talk, I will introduce the detail and result of the experiments, and our future plans.

[1] P. Schury et al., Nucl. Inst. Meth. B 335, 39 (2014).
[2] D. Kaji et al., Nucl. Instrum. Meth. B 317, 311 (2013).
[3] Y. Hirayama et al., Nucl. Instrum. Meth. B 412, 11 (2017).
[4] P. Schury et al., Phys. Rev. C 104, L021304 (2021).
[5] T. Niwase et al., Phys. Rev. Lett. 130, 132502 (2023).

Speaker: Dr Toshitaka Niwase (Kyushu University)

20250522INPC.pdf

457 Decay-correlated mass spectrometry

The use of multi-reflection time-of-flight mass spectrometry has become rather popular in the past decade. The technique provides for high mass resolving power ($m/\Delta m\sim10^6$) and fast analysis ($t_{obs}<<100~$ms) which makes it competitive with Penning trap time-of-flight ion cyclotron resonance measurements, with the added advantage of a much greater tolerance for contaminants and the fact that each measured ion carries identical statistical weight -- meaning that even one count could be a valid atomic mass determination. In order to realize such a single-ion measurement, however, it is necessary to fully exclude the possibility that the time-of-flight signal derived from noise or contaminant ions. In order to accomplish this, we have developed ion-detectors which combine a commercial dynode-based ion impact time-of-flight detector with silicon detectors to record $\alpha$- and $\beta$-decay [1,2] as well as spontaneous fission and $\beta$-delayed proton emission. We are in the process, also, of developing a number of new detectors to improve the efficiency of the decay detection and extend the technique to include X-rays and $\gamma$-rays. The addition of X-rays and $\gamma$-rays will be critical to future plans for exploring the actinide and trans-actinide region by multi-nucleon transfer reaction, wherein nuclides on both sides of $\beta$-stability are produced and conjugate nuclei are often difficult to mass resolve.
I will present a detailed review of the existing detectors' performance along with some discussion of our new detector plans. Depending on the 2025 springtime accelerator schedule, first results of the new detector for X-/$\gamma$-ray correlated mass spectrometry may also be presented.

[1] T. Niwase et al., NIM A 953 (2020) 163198
[2] T. Niwase et al., PTEP Volume 2023, Issue 3 (2023) 031H01

Speaker: Peter Schury (KEK Wako Nuclear Science Center)

Presentation_ID364_Schury.pptx

458 Accessing the immediate vicinity of tin-100 with a hot cavity laser ion source

The different configurations of the atomic nucleus, a self-bound quantum mechanical mesoscopic system, form a landscape of over 3000 known isotopes. However, even more than 100 years since its discovery by Ernest Rutherford, the complexity of the nucleus continues to elude a global theoretical description. To drive theory development, new experimental data are required from unexplored reaches of the chart of nuclei. A key area for new data is the immediate region below the heaviest bound self-conjugate nucleus, tin-100. This proton-rich region past the $N=Z=50$ shell closure has been and continues to be the subject of intense experimental and theoretical research [1]. However, only limited information is available for the ground-state properties in the region, mainly due to challenges in producing these isotopes with sufficiently high yields. Recently, new ultra-sensitive measurement techniques developed at the University of Jyväskylä Accelerator Laboratory opened the immediate vicinity of tin-100 to optical spectroscopy and mass spectrometry studies [2,3].

Here I will present our most recent result on mass and optical studies on silver [4] and palladium isotope chains, culminating on the masses of $N=Z$ isotopes 94-Ag and 92-Pd which we recently accessed at the IGISOL facility at the University of Jyväskylä Accelerator Laboratory.

[1] Magdalena Górska. “Trends in the Structure of Nuclei near 100Sn”. en. In: Physics 4.1 (Mar. 2022). Number: 1 Publisher: Multidisciplinary Digital Publishing Institute, pp. 364–382
[2] M. Reponen et al. “An inductively heated hot cavity catcher laser ion source”. In: Review of Scientific Instruments 86.12 (Dec. 2015), p. 123501.
[3] M. Reponen et al. “Evidence of a sudden increase in the nuclear size of proton-rich silver-96”. en. In: Nature Communications 12.1 (July 2021), p. 4596.
[4] Z. Ge et al. High-precision mass measurements of neutron deficient silver isotopes probe the robustness of the $N$ = 50 shell closure. Phys. Rev. Lett. 133, 132503, (2024).

Speaker: Mikael Reponen (University of Jyväskylä)

Presentation_ID435_Reponen.pdf

459 Mass measurements of short-lived nuclides using Brho-defined IMS at CSRe

Accurate nuclear masses not only provide indispensable information on nuclear structure, but also deliver important input data for applications in nuclear astrophysics. The challenge today is to obtain accurate masses of nuclei located far away from the valley of stability. Recently, we have developed a brand new technique, the Brho-defined isochronous mass spectrometry (IMS), at the cooler storage ring CSRe in Lanzhou. Using the simultaneously determined revolution times and velocities of the stored ions, the relation between ions’ magnetic rigidities and orbit lengths is established, allowing to determine the magnetic rigidity of any stored ion according to its orbit length. Consequently, m/q values of the unknown-mass nuclides are determined. High mass resolving power has been achieved covering a large m/q-range over the full Brho-acceptance of the storage ring, starting a new era of the IMS. By using the Brho-defined IMS, the masses of 70Kr, 66Se, 64As, 62Ge, 23Si, 26P, 27S, 31Ar were measured for the first time and the mass precision was improved for some other nuclides. The new mass results were used to study relevant problems in nuclear structure and astrophysics [1,2,3].
1. X. Zhou et al., Nature Physics 19, 1091–1097 (2023)
2. M. Wang et al., Phys. Rev. Lett. 130, 192501 (2023)
3. Y. Yu et al., Phys. Rev. Lett. 133, 222501 (2024)

Speaker: Meng Wang (Institute of Modern Physics, Chinese Academy of Sciences)

INPC2025-ID484-wang.pptx

460 Pushing the boundaries at FRIB: High-Precision Mass Measurements Near The Proton Dripline

With new radioactive-ion-beam facilities such as FRIB becoming operational, the properties of nuclei in close proximity to the driplines are coming within reach of high-precision measurements. Within the last year, at a fraction of FRIB’s ultimate beam intensity, we used the LEBIT facility [1] to successfully perform Penning-trap mass measurements of 101Sn, 103Sn [2], 23Si, and 22Al [3]. These masses are critical for nuclear astrophysics and nuclear structure studies, providing insights into the smoothness of the mass surface, and determining the level ordering and isospin symmetry breaking effects. As FRIB ramps up its beam intensity, the production of many more nuclei will enable new and exceptional research opportunities. However, the short half-lives of many of these nuclei pose challenges for Penning-trap mass spectrometry. To overcome these limitations, we are developing a next-generation MR-ToF device at FRIB based on the work in [4].
In this contribution, I will discuss the mass measurements of 101,103Sn, and 23Si and their significance for nuclear physics, along with an overview of the ongoing development of a next-generation MR-ToF device that will expand the mass measurement and separation capabilities of FRIB.
[1] R. Ringle, S. Schwarz and G. Bollen, Penning trap mass spectrometry of rare isotopes produced via projectile fragmentation at the LEBIT facility, IJMS 349-350, 87 (2013).
[2] C.M. Ireland, F.M. Maier et al., High-Precision mass measurements of 103Sn restores smoothness of the mass surface, PRC 111, 014314 (2025).
[3] S.E. Campbell et al., Precision Mass Measurement of the Proton Dripline Halo Candidate 22Al, PRL 131, 152501 (2024).
[4] F.M. Maier et al., Increased beam energy as a pathway towards a highly selective and high-flux MR-ToF mass separator, NIMA 1056, 168545 (2023).

Speaker: Franziska Maria Maier (FRIB)

Presentation_ID543_Maier.pptx

Parallel Session: 8_Outreach and Science Education

Convener: Hyunju Lee (Ewha Womans University)

461 Training the Future Workforce in Nuclear Science: Challenges and Opportunities

A sustained and skilled workforce is crucial for advancing nuclear science, both in uncovering the fundamental building blocks of matter and in developing innovative nuclear technologies. This presentation underscores a long-term dedication to training and inspiring students across all educational levels—from middle and high schools to universities—through active engagement in nuclear physics research projects. Additionally, it highlights ongoing efforts and future initiatives to expand global STEM outreach via the cosmic ray muon detector network, gLOWCOST, designed at Georgia State University to monitor dynamic changes in space and terrestrial weather. Our STEM model is: "Inspire to learn, Empower to know, Engage to participate, and Enjoy to live."

Speaker: Prof. Xiaochun He (Georgia State University)

Presentation_ID317_HE.pdf

Presentation_ID317_HE.pptx

462 Outreach and Science Education in the European Physics Community

Outreach and science education are essential for making scientific inquiry accessible to a wider audience. These efforts help people understand how scientists acquire knowledge through experiments and observations, emphasizing evidence-based learning and the importance of repeatability in research. By engaging the public, outreach initiatives foster scientific literacy and empower individuals to think critically about the world. Many scientific communities are committed to promoting these efforts, as demonstrated by various national and international projects, particularly within the European nuclear physics community, which aim to broaden the impact of nuclear science through large-scale initiatives.

Speaker: Alessandra Fantoni (INFN Laboratori Nazionali di Frascati)

Presentation_ID726_Fantoni.pdf

463 IPPOG : The International Particle Physics Outreach Group - Engaging the world with science

The pillar for outreach in particle physics, which is nowadays an integral part of our work as researchers, is IPPOG, the International Particle Physics Outreach Group. IPPOG is a network of scientists, science educators and communication specialists working across the globe in informal science education and public engagement for particle physics. The flagship activity of IPPOG is the International Particle Physics Masterclasses programme, to which other activities such as the Worldwide Data Day, the International Muon Week and International Cosmic Day organisation have been added. IPPOG members also participate in a wide range of events: public talks,festivals, exhibitions, teacher training, student competitions, and open days at local institutes. A resource database has also been developed containing a wealth of material for the dissemination of particle physics. In this paper the history and evolution of IPPOG is presented briefly, and its various activities are discussed, with emphasis on the masterclasses, which have been expanding both geographically and in scope during the years.

Speaker: Dr Despina Hatzifotiadou (INFN Bologna)

Presentation_706_Hatzifotiadou.pptx

464 High School Students' Interest in Particle Physics

Particle physics is a field of study that explores the fundamental particles and their interactions based on quantum mechanics and the theory of relativity, aiming to understand the foundation of the universe and nature. Advances in particle physics have become the basis for modern technologies such as medicine and artificial intelligence, significantly impacting everyday life.
The findings of an investigation into high school students' interest in particle physics revealed that students showed high interest in applications related to real-life contexts, such as medicine and technology. However, their interest in the principles of particle physics and basic scientific inquiry was relatively low. Additionally, differences in interest areas were observed based on students' chosen subjects, with significant disparities identified between general high school and science high school students.
To increase interest in particle physics, it is necessary to provide educational materials connected to careers and everyday life. Furthermore, opportunities to explore complex scientific principles and engage in discussions on the relationship between science and societal phenomena should be incorporated. This approach can motivate students to learn about particle physics, help them understand its societal and technological significance, and provide valuable opportunities to appreciate the importance of scientific advancements.

Speaker: Su-Kyeong Lee (Jeonbuk National University)

Presentation_ID711_Lee.pdf

Presentation_ID711_Lee.pptx

465 Cross Pollination of Artistic Ideas To Enhance Engagement At Grass Root Level

The nuclear industry is at a cornerstone of global energy security and technological advancement. It however faces some significant challenges in fostering diversity and inclusion (D&I) across its workforce. Starting science engagement at an earlier stage ensures addressing public misconceptions surrounding the nuclear sector. Development of interactive educational practices, such as using dance to demystify complex concepts can inspire generate a sustaining interest in nuclear science through curiosity.
Collaborations between artists and scientists can create accessible and inclusive STEM pathways, particularly targeting underrepresented communities and young learners. Initiatives like mobile science danceathons, nuclear themed theatre actives and interactive workshop are effective tools for fostering curiosity and dismantling stereotypes about careers in nuclear.
Furthermore, the role of social media and digital platforms in amplifying these creative outreach efforts with a focus on designing compelling narratives that emphasize the role of arts in innovation, and global sustainability.. Engaging with influencers and content creators content creators globally to teach and inspire next generation can bridge generational gaps and resonate with diverse audiences.
By adopting these forward-looking strategies, the nuclear sector can not only attract and inspire the next generation of talent but also cultivate a scientifically literate society that supports its critical contributions to energy, health, and security.

Speaker: Kinjal Dave (BAE Systems)

13:00 Lunch

IUPAP Award

Convener: Eberhard Widmann (Austrian Academy of Sciences)

Plenary Session: 8

Convener: Carlos Bertulani (East Texas A&M University)

466 Production and Experiments with Rare Isotope Beams at FRIB

The Facility for Rare Isotope Beams, FRIB, is a US Department of Energy User Facility dedicated to providing beams of rare isotopes for researchers from around the world. FRIB began operation in May 2022 and has since produced over 280 rare isotopes for research ranging from the study of halo nuclei to the measurement of reaction rates relevant to astrophysical processes. FRIB uses a high-power superconducting LINAC to accelerate beams from oxygen to uranium to around 200 MeV/u. Novel features include multiple charge-state acceleration and stripping of electrons with a flowing lithium film. The primary beam from the LINAC reacts with a rotating carbon target and rare isotopes are collected and separated with a fragment separator. The talk will provide an overview of rare isotope production and separation at FRIB. Examples of early science from FRIB, including production of 11 new isotopes, will be presented. The benefits of an FRIB400 upgrade will be presented.

Speaker: Bradley Sherrill (FRIB)

Presentation_ID467_Sherrill.pptx

467 New 12C(α, γ)16O reaction rate and its astrophysical implications

The 12C(α, γ)16O reaction is one of the most crucial reactions in nuclear astrophysics, and thus in the past several decades attracts great efforts that further our understanding of this fundamental reaction [1]. The properties of several states in 16O strongly affect the 12C(α, γ)16O reaction rate. In recent years we developed an independent technique based on the (11B, 7Li) transfer reaction [2,3], and with this technique constrained the contributions from the external capture [4] and two subthreshold resonances [5,6] by measurement of properties of the ground state and the excited states at Ex = 6.917 MeV and 7.117 MeV in 16O. An increase of up to 21% in the total reaction rate is found within the temperature range of astrophysical relevance compared with the previous recommendation of a recent review. The updated 12C(α, γ)16O reaction rate decreases the lower and upper edges of the mass gap of black holes about 12% and 5%, respectively [7]. Furthermore, we found that in a sufficiently hot and dense astrophysical environment the 12C(α, γ)16O rate is enhanced by a factor of 8.1 at typical temperature of 0.1 GK in inner AGB stars due to change of the effective width of the excited state at Ex = 9.558 MeV of 16O. Such enhanced rate well matches the observations of single CEMP stars with the stellar modelling, and thus presents an explanation of the formation of single CEMP stars [8].

References:
[1] R. J. deBoer, J. Görres, M. Wiescher et al., Rev. Mod. Phys. 89, 035007 (2017).
[2] Y. P. Shen, B. Guo, T. L. Ma et al., Phys. Lett. B 797, 134820 (2019).
[3] Y. P. Shen, B. Guo, W. P. Liu, Prog. Part. Nucl. Phys. 119, 103857 (2021).
[4] Y. P. Shen, B. Guo, R. J. deBoer et al., Phys. Rev. Lett. 124, 162701 (2020).
[5] Y. P. Shen, B. Guo, Z. H. Li et al., Phys. Rev. C 99, 025805 (2019).
[6] W. Nan, Y. P. Shen, B. Guo et al., Phys. Rev. C 109, 045808 (2024).
[7] Y. P. Shen, B. Guo, R. C. DeBoer et al., Astrophys. J. 945, 41 (2023).
[8] G. Fu, Z. An, S. Jin, B. Guo, submitted.

Speaker: Prof. Bing Guo (China Institute of Atomic Energy)

Presentation_ID441_Guo.pptx

468 Machine Learning and Quantum Computing Algorithms for Nuclear Many-Body Systems

I discuss recent developments in applying machine learning and quantum computing algorithms to the study of nuclear many-body systems. I cover several techniques developed by my research group with collaborators as well as those introduced by others in the field.

Speaker: Dean Lee (Michigan State University)

Lee_MachineLearningQuantumComputing2025.pptx

469 Yemilab - Korea's new underground laboratory

Yemilab is a new underground research facility in Korea, located 1,000 meters below ground within an active iron mine. The laboratory includes two large cavities for large-scale experiments and about 3,000 square meters of tunnel-based laboratory space. Access to the lab is provided by a rampway, which can accommodate large trucks, and a 600-meter vertical elevator shaft. At the base of these access points, a 700-meter-long tunnel leads to the main laboratory area.

The primary scientific programs at Yemilab focus on dark matter searches and neutrinoless double beta decay experiments. The COSINE experiments, which use updated NaI(Tl) crystals, will follow the COSINE-100 experiment conducted at Y2L. The AMoRE experiment, which uses lithium molybdate crystals coupled with low-temperature calorimetric sensors, searches for the neutrinoless double beta decay of Mo-100 isotopes. The first phase of AMoRE-II is scheduled to begin in 2025.

Other research programs at Yemilab include low-mass dark matter experiments, rare beta decay searches, and the development of ultra-low background environmental techniques. In addition to these flagship experiments, the facility also supports interdisciplinary research with several applications in other fields.

Speaker: Yeongduk Kim (Institute for Basic Science)

inpc-yemilab-v2.pdf

Closing Ceremony

17:30 Break

Public Lecture