Matter radii of the ${}^{34–40}\mathrm{Mg}$ nuclei are investigated by self-consistent Hartree-Fock-Bogolyubov calculations assuming the axial symmetry. With the semirealistic M3Y-P6 interaction, the $N$ dependence of the matter radii observed in the experiments is reproduced excellently. Both the pairing and the deformation play significant roles in an intertwined manner. The ${}^{35}\mathrm{Mg}$ nucleus has a smaller radius than the neighboring even-$N$ nuclei, which is attributed to its smaller deformation. On the other hand, a neutron halo is obtained in ${}^{37}\mathrm{Mg}$. We point out that, in contrast to the pairing antihalo effect that may operate on the even-$N$ nuclei, the pair correlation enhances halos in odd-$N$ nuclei, owing to the new mechanism which we call unpaired-particle haloing. The halo in ${}^{37}\mathrm{Mg}$ is predicted to have a peanut shape in its intrinsic state, reflecting $p$-wave contribution as in ${}^{40}\mathrm{Mg}$. The $N$ dependence of the deformation is significant again, by which the single-particle level dominated by the $p$-wave component comes down.

• Received 1 May 2018

DOI:https://doi.org/10.1103/PhysRevC.98.011301