High-resolution spectroscopy of neutron-rich Br isotopes and signatures for a prolate-to-oblate shape transition at N=56

TL;DR

This study provides detailed spectroscopic data on neutron-rich Br isotopes, revealing a shape transition from prolate to oblate at N=56, supported by experimental results and advanced shell-model calculations.

Contribution

It presents the first systematic experimental investigation of these isotopes using state-of-the-art techniques and compares findings with modern theoretical models.

Findings

Identification of shape transition at N=56

Spectroscopic data for isotopes $^{87-93}$Br

Agreement with shell-model predictions

Abstract

The first systematic experimental study of the neutron-rich Br isotopes with two complementary state-of-the-art techniques is presented. These isotopes have been populated in the fission process at two different facilities, GANIL and ILL. New spectroscopic information has been obtained for odd-even $^{87-93}$Br isotopes and the experimental results have been compared with state-of-the-art Large-Scale Shell-Model and DNO Shell-Model calculations. As a result of such theoretical approaches, a transition from prolate ($^{87,89}$Br) to oblate ($^{91,93}$Br) shapes is obtained from the subtle balance between proton and neutron quadrupole deformations, as a clear signature of pseudo-SU3 quadrupole regime.