Shell model studies of nuclei withA=92–98

Abstract

Shell model calculations are carried out for the spectra of nuclei with $92<~A<~98$ in the model space in which the valence protons occupy the ${1f}_{5/2},$ ${2p}_{3/2},$ ${2p}_{1/2},$ and ${1g}_{9/2}$ orbitals, and valence neutrons occupy ${1g}_{9/2},$ ${2p}_{1/2},$ ${2d}_{5/2},$ ${2d}_{3/2},$ ${3s}_{1/2},$ and ${1g}_{7/2}$ orbitals using a partition truncation method. We first select partitions that are big enough to describe the spectra of nuclei with $N=50.$ Then we combine all possible valence neutron partitions with the selected valence proton partitions of the corresponding nuclei with $N=50$ to diagonalize the Hamiltonians for the nuclei with $54>~N>~51.$ The weak-coupling scheme is used to analyze the experimental data and the calculated results. The concepts of independent nucleon-pair motion in even-even nuclei and the homologous state structure in even-odd nuclei are held in this mass region. The spectra of ${}_{42}^{95}{\mathrm{Mo}}_{53}$ and ${}_{43}^{95}{\mathrm{Tc}}_{52}$ share a special similar structure; i.e., the low-lying states of ${}_{42}^{95}{\mathrm{Mo}}_{53}$ up to 2.5 MeV can be obtained by replacing the last odd proton in ${}_{43}^{95}{\mathrm{Tc}}_{52}$ and vice versa.