Nilsson diagrams for light neutron-rich nuclei with weakly-bound neutrons

Abstract

Using Woods-Saxon potentials and the eigenphase formalism for one-particle resonances, one-particle bound and resonant levels for neutrons as a function of quadrupole deformation are presented, which are supposed to be useful for the interpretation of spectroscopic properties of some light neutron-rich nuclei with weakly bound neutrons. Compared with Nilsson diagrams in textbooks that are constructed using modified oscillator potentials, we point out a systematic change of the shell structure in connection with both weakly bound and resonant one-particle levels related to small orbital angular momenta $\ensuremath{\ell}$. Then, it is seen that weakly bound neutrons in nuclei such as $^{15\ensuremath{-}19}\mathrm{C}$ and $^{33\ensuremath{-}37}\mathrm{Mg}$ may prefer being deformed as a result of the Jahn-Teller effect, due to the near degeneracy of the $1{d}_{5/2}\text{\ensuremath{-}}2{s}_{1/2}$ levels and the $1{f}_{7/2}\text{\ensuremath{-}}2{p}_{3/2}$ levels in the spherical potential, respectively. Furthermore, the absence of some one-particle resonant levels compared with the Nilsson diagrams in textbooks is illustrated.