Ground-State Electromagnetic Moments of Calcium Isotopes

TL;DR

This study used laser spectroscopy to measure electromagnetic moments of calcium isotopes, providing new data that tests and supports modern nuclear shell-model theories, especially for neutron-rich isotopes.

Contribution

First measurement of ground state magnetic and quadrupole moments for several calcium isotopes, including the model-independent determination of $^{51}$Ca's spin.

Findings

Excellent agreement with chiral effective field theory predictions for neutron-rich isotopes.

Evidence of particle-hole excitations in lighter isotopes.

First determination of $^{51}$Ca ground state spin $I=3/2$.

Abstract

High-resolution bunched-beam collinear laser spectroscopy was used to measure the optical hyperfine spectra of the $^{43-51}$Ca isotopes. The ground state magnetic moments of $^{49,51}$Ca and quadrupole moments of $^{47,49,51}$Ca were measured for the first time, and the $^{51}$Ca ground state spin $I=3/2$ was determined in a model-independent way. Our results provide a critical test of modern nuclear theories based on shell-model calculations using phenomenological as well as microscopic interactions. The results for the neutron-rich isotopes are in excellent agreement with predictions using interactions derived from chiral effective field theory including three-nucleon forces, while lighter isotopes illustrate the presence of particle-hole excitations of the $^{40}$Ca core in their ground state.