Abstract
The hyperfine coupling constants of neutron deficient 37Ca were deduced from the atomic hyperfine spectrum of the 4s2S1/2↔4p2P3/2 transition in Ca ii, measured using the collinear laser spectroscopy technique. The ground-state magnetic-dipole and spectroscopic electric-quadrupole moments were determined for the first time as μ=+0.7453(72)μN and Q=−15(11)e2fm2, respectively. The experimental values agree well with nuclear shell-model calculations using the universal sd model-space Hamiltonians versions A and B (USDA/B) in the sd-model space with a 95% probability of the canonical nucleon configuration. It is shown that the magnetic moment of 39Ca requires a larger non-sd-shell component than that of 37Ca for good agreement with the shell-model calculation, indicating a more robust closed subshell structure of 36Ca at the neutron number N=16 than 40Ca. The results are also compared to valence-space in-medium similarity renormalization group calculations based on chiral two- and three-nucleon interactions.