Evolution of single-particle structure of silicon isotopes

Abstract

New data on proton and neutron single-particle energies $E_{nlj}$ of Si isotopes with neutron number $N$ from 12 to 28 as well as occupation probabilities $N_{nlj}$ of single particle states of stable isotopes ${}^{28,30}$Si near the Fermi energy were obtained by the joint evaluation of the stripping and pick-up reaction data and excited state decay schemes of neighboring nuclei. The evaluated data indicate following features of single-particle structure evolution: persistence of $Z=14$ subshell closure with $N$ increase, the new magicity of the number $N=16$, and the conservation of the magic properties of the number $N=20$ in Si isotopic chain. The features were described by the dispersive optical model. The calculation also predicts the weakening of $N=28$ shell closure and demonstrates evolution of bubble-like structure of the proton density distributions in neutron-rich Si isotopes.

Comments: 14 pages, 12 figures, accepted for publication in the European Physical Journal A - "Hadrons and Nuclei"