E2 collectivity in shell-model calculations for odd-mass nuclei near 132Sn

T J Gray,L A Fuderer,J M Allmond,A E Stuchbery

doi:10.1051/epjconf/202023204007

T J Gray, L A Fuderer + Show 2 more

Open Access

https://doi.org/10.1051/epjconf/202023204007

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Abstract

Shell-model calculations for 127,129In and 129,131Sb are presented, and interpreted in the context of the particle-core coupling scheme, wherein proton g9/2 holes or g7/2 particles are added to semimagic 128,130Sn cores. These results indicate that the particle-core coupling scheme is appropriate for the Sb isotopes, whilst less so for the In isotopes. B(E2) excitation strengths are also calculated, and show evidence of enhanced collectivity in both Sb isotopes, especially 131Sb. This observation suggests that 131Sb would be an excellent case for an experimental study seeking to investigate the early onset of collectivity near 132Sn.

Highlights

The emergence of nuclear collectivity from the underlying nucleonic motion is a leading inquiry in nuclear structure research [1]
The excited states of nuclei near doublemagic shell closures are well described by the nuclear shell model
Results indicate that in contrast, for the In isotopes, the particle-core “multiplet” configurations are highly fragmented over several excited states, so that the simplicity of the E2 sum rule is lost. 131Sb looks to be a promising candidate for experimental Coulomb excitation studies that could help elucidate the emergence of quadrupole collectivity as protons and neutrons are added to doubly magic 132Sn

Summary

Introduction

The emergence of nuclear collectivity from the underlying nucleonic motion is a leading inquiry in nuclear structure research [1]. The excited states of nuclei near doublemagic shell closures are well described by the nuclear shell model. In regions away from shell closures, collective phenomena such as vibrations or rotations dominate the low-excitation behaviour of the nucleus. Understanding how and why the collective phenomena emerge from the underlying nucleon-nucleon interactions remains an open question. Studies of emerging collectivity examine chains of even-even nuclei that transition from the single-particle toward collective limits. We present systematic shell-model calculations of odd-mass nuclei around 132Sn and their semimagic eveneven Sn cores, with a view to aiding experimental investigation into the question of emerging collectivity when a single proton (or hole) is added to a notional core

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