Moments and radii of exotic Na and Mg isotopes

The ground-state properties of neutron-rich exotic Na and Mg isotopes with even numbers of neutrons, N, are studied up to drip lines. The shell-model calculations with an ab initio effective nucleon-nucleon interaction reported by Tsunoda, Otsuka, Takayanagi et al. [Nature (London) 587, 66 (2020)] are extended to observables such as magnetic dipole and electric quadrupole moments, and charge and matter radii. Good agreements with experimental data are found, and predictions are shown up to drip lines. A prescription to extract the deformation parameters for the eigenstates of the Monte Carlo shell model is presented, and the obtained values are used to calculate charge and matter radii. The increase of these radii from the droplet model is described as the consequences of the varying deformation of the surface and the growing neutron excitations or occupations in the pf shell, consistent with the drip-line mechanism presented in the above reference. The neutron skin thickness is shown to be about 0.1 fm for N = 20, which can be compared to the value for Pb-208 in an A(1/3) scaling. The relation of the neutron skin thickness to the electromagnetic moments is discussed for an exotic nucleus, Na-31.

Automated summary

The ground-state properties of neutron-rich exotic Na and Mg isotopes with even numbers of neutrons, N, are studied up to drip lines. The shell-model calculations with an ab initio effective nucleon-nucleon interaction reported by Tsunoda, Otsuka, Takayanagi et al. are extended to observables such as magnetic dipole and electric quadrupole moments, and charge and matter radii. Good agreements with experimental data are found, and predictions are shown up to drip lines.