Signatures of octupole shape phase transitions in radioactive nuclei

TL;DR

This paper investigates octupole shape phase transitions in medium-heavy and heavy nuclei using nuclear energy density functional theory and boson models, revealing systematic behaviors indicating shape transitions in certain isotopes.

Contribution

It introduces a combined microscopic and bosonic approach to identify signatures of octupole shape phase transitions in specific nuclear regions.

Findings

Systematic spectroscopic behaviors indicate phase transitions.

Octupole deformation and vibration coexist in certain isotopes.

The approach links potential energy surfaces to observable properties.

Abstract

We analyze the octupole deformations and the related collective excitations in medium-heavy and heavy nuclei based on the microscopic framework of the nuclear energy density functional theory. Constrained self-consistent mean-field calculation with a given energy density functional is performed to provide for each nucleus a potential energy surface with axial quadrupole and octupole shape degrees of freedom. Spectroscopic properties are computed by means of the interacting-boson Hamiltonian, which is determined by mapping the fermionic potential energy surface onto the bosonic counterpart. The overall systematics of the calculated spectroscopic observables exhibit phase transitional behaviors between stable octupole deformation and octupole vibration characteristic of the octupole-soft potential within the set of nuclei in light actinide and rare-earth regions, Th, Ra, Sm, Gd, and Ba isotopes, where octupole shapes are most likely to occur.