Consistent description of nuclear charge radii and electric monopole transitions

TL;DR

This paper uses the interacting boson model to systematically describe energy spectra, charge radii, and electric monopole transitions across rare-earth nuclei, highlighting successes and limitations related to nuclear shape deformations.

Contribution

It provides a consistent IBM framework for describing charge radii and monopole transitions, revealing its applicability and limitations in the rare-earth region.

Findings

IBM accurately describes spherical-to-deformed shape transitions.

The model successfully predicts charge radii and monopole transitions for most nuclei.

Breakdown occurs in tungsten isotopes, likely due to hexadecapole deformation.

Abstract

A systematic study of energy spectra throughout the rare-earth region (even-even nuclei from $_{58}$Ce to $_{74}$W) is carried out in the framework of the interacting boson model (IBM), leading to an accurate description of the spherical-to-deformed shape transition in the different isotopic chains. The resulting IBM Hamiltonians are then used for the calculation of nuclear charge radii (including isotope and isomer shifts) and electric monopole transitions with consistent operators for the two observables. The main conclusion of this study is that an IBM description of charge radii and electric monopole transitions is possible for most of the nuclei considered but that it breaks down in the tungsten isotopes. It is suggested that this failure is related to hexadecapole deformation.