Beta-decay study on the neutron-unbound states in 133Sn at ISOLDE Decay Station

In this contribution, we will present a recent experimental work studying the neutron-unbound states in 133Sn from the beta decay of 133In at ISOLDE Decay Station. The beta decay in this region ($Z<50$ and $N>82$) is characterized by a large beta-decay energy window $Q_{\beta}$ and low neutron separation energy Sn. Due to the valence proton and neutron orbitals having opposite parities, Gamow-Teller transitions create deep-neutron holes in the 132Sn core. The large N=82 shell gap makes these neutron-hole states in 133Sn neutron unbound. The neutron time-of-flight detector VANDLE was used to identify these states for the first time. Neutron resonances were observed at energies between 1.5 and 3.7 MeV corresponding to candidate 11/2- (h11/2), 3/2+ (d3/2), 1/2+ (s1/2), and 7/2+ (g7/2). The neutron h11/2 state had been previously identified in gamma-ray spectroscopy, suggesting a strong suppression of the neutron emission channel. In this experiment, for the first time in the 132Sn region, it was possible to observe the neutron emission from a gamma-decaying state, thus allowing to establish partial decay widths for the gamma and neutron channels. Partial decay widths can be useful to calculate (n,$\gamma$) capture rates for rapid neutron capture (r-process) abundance calculations.