Magnetic moments of low-lying states in tin isotopes within the nucleon-pair approximation

Abstract

The magnetic moments of the first excited ${2}^{+}$ state in even-even nuclei ${}^{102--130}$Sn and the low-lying yrast states in odd-mass nuclei ${}^{101--109,123--131}$Sn are calculated within the framework of the nucleon-pair approximation (NPA) of the shell model, by using the standard multipole-multipole interaction. Our calculations agree reasonably well with available experimental data. The $g({2}_{1}^{+})$ values, as well as the contributions from their spin and orbital angular momentum components, are evaluated in terms of the small NPA subspace spanned by $S$ and $D$ nucleon pairs. The magnetic moment is suggested to be a sensitive probe of the nuclear wave function in this region.