Speaker
Description
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.
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