Oct 3 – 7, 2022
Science Culture Center, IBS
Asia/Seoul timezone

WISArD experiment: the precision frontier of BSM

Oct 4, 2022, 9:44 PM
S236 (Science Culture Center, IBS)


Science Culture Center, IBS

55 EXPO-ro, Yuseong-gu, Daejeon
Poster Session Poster Session


Jeongsu Ha (Instituut voor Kern- en Stralingsfysica, KU Leuven)


In the standard electroweak model, the weak current with a Vector – Axial-vector (V-A) form explains the weak interaction in a phenomenological context. However, the Lee-Yang Hamiltonian conserving Lorentz symmetry allows right-handed (V+A) as well as scalar, and tensor currents. For decades there have been efforts searching for such exotic currents as a test of the standard model. In particular, beta decay has been a powerful tool since the exotic currents are related to its kinematics [Ja57]. Furthermore, its precision is comparable with high energy physics experiments [Go19].

The WISArD experiment, succeeding the WITCH experiment, has carried out the weak interaction studies at the ISOLDE facility. We employ the beta-delayed proton emission of 32Ar to search for a scalar current in beta-neutrino correlations. The extent of the proton kinetic energy shift provides information indirectly on the kinematics of beta-decay recoil nuclei, which is different between scalar- and vector-type interactions.

In the WISArD setup, the 30-keV 32Ar+ ions are implanted in the catcher foil at the center. The positrons emitted upwards are guided by the field of a superconducting magnet and detected by a scintillator. Silicon detectors surrounding the catcher foil measure the kinematic shift of the beta-delayed protons. A proof-of-principle campaign was executed in 2018 [Ar20] and reached the 3rd best value for the angular correlation coefficients of vector decays. After upgrading the apparatuses, the first part of a new experiment was done in October 2021. We present details of the experimental devices and recent technical development for the setup.

[Ja57] J. D. Jackson, S. B. Treiman, and H. W. Wyld, Phys. Rev. 106, 517 (1957).
[Go19] M. Gonzàlez-Alonso et al, Prog. Part. Nucl. Phys. 104, 165 (2019).
[Ar20] V. Araujo-Escalona et al., Phys. Rev. C 101, 055501 (2020).

Primary authors

Jeongsu Ha (Instituut voor Kern- en Stralingsfysica, KU Leuven) Dr Philippe Alfaurt (CENBG, Bordeaux) Dr Pauline Ascher (CENBG, Bordeaux) Dr Dinko Atanasov (CENBG, Bordeaux) Dr Bertram Blank (CENBG, Bordeaux) Ms Federica Cresto (LPC Caen) Dr Laurent Daudin (CENBG, Bordeaux) Dr Xavier Flechard (LPC Caen) Dr Laurent Leterrier (LPC Caen) Dr Razvan Lica (CERN) Dr Etienne Lienard (LPC Caen) Dr Alejandro Garcia (University of Washington) Dr Mathias Gerbaux (CENBG, Bordeaux) Dr Jerome Giovinazzo (CENBG, Bordeaux) Dr Stephane Grevy (CENBG, Bordeaux) Dr Dan Melconian (Texas A&M University) Mr Morgan Nasser (Texas A&M University) Dr Marcin Pomorski (CENBG, Bordeaux) Dr Mathieu Roche (CENBG, Bordeaux) Dr Nathal Severijns (Instituut voor Kern- en Stralingsfysica, KU Leuven) Mr Simon Vanlangendonck (Instituut voor Kern- en Stralingsfysica, KU Leuven) Dr Dalibor Zakoucky (Nuclear Physics Institute of the Czech Academy of Sciences)

Presentation materials