Nuclear shape / phase transitions in the N = 40, 60, 90 regions

TL;DR

This paper studies shape and phase transitions in isotopes of Se, Zr, Mo, and Nd around neutron numbers 40, 60, and 90, combining experimental indicators with microscopic and macroscopic models to understand structural evolution.

Contribution

It integrates experimental data with microscopic mean-field and macroscopic algebraic models to analyze nuclear shape transitions in specific isotopic regions.

Findings

Evidence of first-order shape/phase transitions from spherical to deformed structures.

Structural changes observed through energy ratios and B(E2) transition rates.

Potential energy curves align with theoretical models of shape transitions.

Abstract

We investigate the isotopes of Se, Zr, Mo and Nd in the regions with N = 40, 60 and 90, where a first-order shape / phase transition, from spherical to deformed, can be observed. The signs of phase transitional behavior become evident by examining structure indicators, such as certain energy ratios and B(E2) transition rates and, in particular, how they evolve with neutron number. Microscopic mean-field calculations using the Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer framework also reveal structural changes when considering the evolution of the resulting potential energy curves as functions of deformation. Finally, macroscopic calculations, using the Algebraic Collective Model, specifically for $^{74}$Se, $^{102}$Mo and $^{150}$Nd, after fitting its parameters to experimental spectra, result in potentials that resemble some of the potentials proposed in the framework of the Bohr Hamiltonian to describe shape transitions in nuclei.