$(h_{11/2})^2$ alignments in neutron-rich $^{132}$Ba with negative-parity pairs

TL;DR

This study uses a shell-model approach with negative-parity pairs to analyze the $(h_{11/2})^2$ alignment in neutron-rich $^{132}$Ba, predicting an isomer and confirming deformation characteristics.

Contribution

It introduces a shell-model collective-pair truncation method with negative-parity pairs to study specific alignments in $^{132}$Ba, providing new predictions and deformation insights.

Findings

Proposed an $E ext{~}4.6$ MeV isomer with $ au ext{~}0.5~ ext{μs}$ in $^{132}$Ba.

Confirmed neutron $(h_{11/2})^{-2}$ alignment in multiple bands.

Identified gamma-unstability and deformation characteristics of $^{132}$Ba.

Abstract

The shell-model collective-pair truncation with negative-parity pairs is adopted to study the $(h_{11/2})^2$ alignment in $^{132}$Ba. The proton $(h_{11/2})^2$-alignment state is predicted as an $E\sim4.6$ MeV and $\tau\sim 0.5~\mu$s isomer with relatively strong E3 decay channels. The oblately deformed neutron $(h_{11/2})^{-2}$ alignment in the yrast band and four negative-parity bands are confirmed, even although two of these negative-parity bands favor the prolate deformation, which directly manifests the $\gamma$ unstability of $^{132}$Ba.