Shell-model study on spectroscopic properties in the region "south" of Pb 208

Abstract

Background: The properties of nuclei located in the region "south"of Pb208 are important for understanding the r-process nucleosynthesis. While some isomeric states and their spectroscopic properties have been investigated experimentally in neutron-rich Pb, Tl, and Hg isotopes recently, a large portion of the area still remains unreachable. Purpose: We aim to study the properties of nuclei in the region south of Pb208, including the binding and excitation energies and electromagnetic properties, in order to predict unknown properties of these nuclei, such as isomerism, utilizing a theoretical model which describes the experimentally known properties precisely. We also address whether the N=126 shell closure is robust or not when the proton number decreases from Pb208. Methods: We performed large-scale shell-model calculations with a new Hamiltonian suggested in the present work. The model space is taken as the 5 proton orbits within 50