Comparative study on charge radii and their kinks at magic numbers

TL;DR

This study compares theoretical models of isotope shifts in charge radii with experimental data, highlighting the importance of tensor interactions, spin-orbit coupling, and single-particle orbitals in reproducing the observed kink behavior at magic numbers.

Contribution

It demonstrates that tensor interactions and specific spin-orbit terms are essential for accurately modeling isotope shift kinks in nuclear charge radii.

Findings

Tensor interactions are crucial for reproducing kink behavior.

Spin-orbit interaction with nonzero isovector channel is necessary.

Single-particle orbitals near Fermi energy influence kink size.

Abstract

Isotope dependences of charge radii, i.e., isotope shifts, calculated by the Skyrme Hartree-Fock, the relativistic mean-field, and the relativistic Hartree-Fock calculations are compared against the experimental data of magic and semimagic nuclei. It is found that the tensor interaction plays a role in reproducing the ``kink'' behavior, irregularity of isotope shifts at the neutron magic number, in the relativistic Hartree-Fock approach. With several Skyrme models, it is found that the kink behavior can be reproduced with the spin-orbit interaction having nonzero isovector channel. The single-particle orbitals near the Fermi energy are crucial to determine the kink size. The effects of the symmetry energy and the pairing interaction are also discussed in relation to the kink behavior.