Charge radii, moments and masses of mercury isotopes across the N = 126 shell closure

TL;DR

This study combines advanced spectroscopic and mass measurement techniques to analyze charge radii and moments of neutron-rich mercury isotopes around the N=126 shell closure, providing insights into nuclear structure and shell effects.

Contribution

It presents new measurements of charge radii, moments, and masses of mercury isotopes, and compares experimental data with covariant density functional theory to understand shell effects.

Findings

Observation of odd-even staggering in charge radii

Identification of a kink at N=126 in charge radii

Dependence of the kink magnitude on orbital occupation and pairing

Abstract

Combining laser spectroscopy in a Versatile Arc Discharge and Laser Ion Source, with Penning-trap mass spectrometry at the CERN-ISOLDE facility, this work reports on mean-square charge radii of neutron-rich mercury isotopes across the $N = 126$ shell closure, the electromagnetic moments of $^{207}$Hg and more precise mass values of $^{206-208}$Hg. The odd-even staggering (OES) of the mean square charge radii and the kink at $N = 126$ are analyzed within the framework of covariant density functional theory (CDFT), with comparisons between different functionals to investigate the dependence of the results on the underlying single-particle structure. The observed features are defined predominantly in the particle-hole channel in CDFT, since both are present in the calculations without pairing. However, the magnitude of the kink is still affected by the occupation of the $1i_{11/2}$ and $2g_{9/2}$ orbitals with a dependence on the relative energies as well as pairing.