Beta-delayed neutron spectroscopy of ¹³²Cd

We studied the beta decay of Z=48, N=84 132Cd at the ISOLDE facility, CERN. Following our recent measurement of the decay of 133In [1], we expected the large majority of the beta- decay strength to populate unbound 1+ states through a Gamow-Teller transformation of a deep g7/2 neutron into a g9/2 proton. Using the neutron time-of-flight detector VANDLE, we find that 2/3 of the neutrons are emitted at 2 MeV. Supported by our new large scale shell model calculation (LSSM) using the N3LO interaction [1], we conclude the beta decay preferentially populates a few 1+ states built on the νg7/2 → πg9/2 transformation. We will show our LSSM produces short half-lives in the Z<50 N=82,84 region, matching well observations, and predicts much shorter half-lives than leading global models [2, 3] for r-process waiting points of Pd and Ru isotopes. We will also present calculations using our LSSM of the neutron branching ratios of N>82 cadmium isotopes, obtaining larger values than global models [2, 3] and matching well observations [4].

[1] Z. Xu et al., Phys. Rev. Lett. 131, 022501 (2023).

[2] P. Moller, M. R. Mumpower, T. Kawano, and W. D. Myers, Atomic Data and Nuclear Data Tables 125, 1 (2019).

[3] I.N. Borzov, Physics of Atomic Nuclei 79, 910 (2016).

[4] V.H. Phong et al., Phys. Rev. Lett. 129, 172701 (2022)