Evolution of nuclear shell structure in neutron-rich nuclei N=32 and N=34

Abstract

This paper presents an overview of the experimental setup to study the structure of unstable nuclear isotopes in the region from ⁴⁷Cl to ⁶³V of the SEASTAR 3 project and the evolution of shell structure in neutron-rich nuclei N=32 and N=34. The first excited energies of Cl, Ar, and K isotopes around N=32, N=34 obtained from the SEASTAR 3 project were determined. The evolution of shell structure in neutron-rich nuclei N=32 và N=34 is explained by the contribution of tensor forces in addition to central and spin-orbit forces. The appearance of new magic neutron N=34 in ⁵⁴Ca is explained due to protonneutron tensor force that pulls neutron 0f_5/2 lower than 1p_1/2 level, leading to not only causes the spin inversion of neutrons at 1p_1/2 and 0f_5/2 levels and enlarges an energy gap between these levels. The change of proton and neutron energy levels in Cl, Ar, and K isotopes around N=32, N=34 driven by tensor force was also discussed in this article.