Physical Review Letters
Author:
Keywords:
Science & Technology, Physical Sciences, Physics, Multidisciplinary, Physics, NUCLEAR-STRUCTURE, 01 Mathematical Sciences, 02 Physical Sciences, 09 Engineering, General Physics, 40 Engineering, 49 Mathematical sciences, 51 Physical sciences
Abstract:
A low-lying state in 131In82, the one-proton hole nucleus with respect to double magic 132Sn, was observed by its γ decay to the Iπ ¼ 1=2− β-emitting isomer. We identify the new state at an excitation energy of Ex ¼ 1353 keV, which was populated both in the β decay of 131Cd83 and after β-delayed neutron emission from 132Cd84, as the previously unknown πp3=2 single-hole state with respect to the 132Sn core. Exploiting this crucial new experimental information, shell-model calculations were performed to study the structure of experimentally inaccessible N ¼ 82 isotones below 132Sn. The results evidence a surprising absence of proton subshell closures along the chain of N ¼ 82 isotones. The consequences of this finding for the evolution of the N ¼ 82 shell gap along the r-process path are discussed.