# Diversity of shapes and rotations in the gamma-soft 130Ba nucleus: first observation of a t-band in the A=130 mass region

## TL;DR

This paper reports the first observation of a two-quasiparticle t-band in 130Ba, revealing diverse shapes and rotational behaviors in a gamma-soft nucleus at medium and high spins, supported by theoretical models.

## Contribution

It presents the first detection of a t-band in the A=130 region and provides comprehensive experimental and theoretical analysis of shape coexistence and rotational modes.

## Key findings

- First observation of a two-quasiparticle t-band in 130Ba
- Identification of multiple new bands including odd-spin partners
- Evidence of shape coexistence and diverse rotational behaviors

## Abstract

Several new bands have been identified in 130Ba, among which there is one with band-head spin 8+. Its properties are in agreement with the Fermi-aligned \nu h11/2^2 , 7/2+[523] \otimes 9/2-[514] Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the A=130 mass region. The t-band is fed by a dipole band involving two additional h11/2 protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, 130Ba presents one of the best and most complete sets of collective excitations that a gamma-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A = 130 mass region.