Ground-state Electromagnetic Moments of Ca37

The hyperfine coupling constants of neutron deficient Ca-37 were deduced from the atomic hyperfine spectrum of the 4s(2)S(1/2) <-> 4p(2)P(3/2) 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 mu = +0.7453(72)mu(N) and Q = -15(11) e(2) fm(2), 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 Ca-39 requires a larger non-sd-shell component than that of Ca-37 for good agreement with the shell model calculation, indicating a more robust closed subshell structure of Ca-36 at the neutron number N = 16 than Ca-40. The results are also compared to valence-space in-medium similarity renormalization group calculations based on chiral two- and three-nucleon interactions.