Proton-neutron-hole states in 51132Sb81 populated in the β-Decay of the doubly closed shell nucleus 132Sn

Abstract

The β-decay of the doubly closed 132Sn nucleide and the accompanying γ-rays in the pn−1 nucleus 51132Sb81 were studied using Ge(Li) and anthracene detectors. The tin samples were produced using the OSIRIS on-line isotope separator for fission fragments of 235U. A half-life of 40±1 sec has been determined for the ground state of 132Sn which decays by a single β-transition to a 1+ level at 1324.3 keV in 132Sb. This level is de-excited by γ-transitions of different energies. The first excited state (3+) of 132Sb occurs at 85.5 keV. Using a delayed-coincidence technique with fast timing, the half-life of this 3+ state has been measured to be T12 = 14.8±1.8 ns. The B(M1) value associated with this transition to the 4+ ground state is compared with the calculated transition probability. The states observed in 132Sb are interpreted in terms of different pn−1 configurations and calculations have been made using a δ-force interaction between the odd proton and the odd-neutron hole. The reduced transition probability for the 40 sec β-decay of 132Sn is compared with the calculated B(GT) value.