Proton-neutron force and proton single-particle strength in Sc, F, and Li isotopes

Abstract

In the present work, the effect of proton-neutron interaction and its different components, i.e., central, spinorbit, and tensor force, on proton shell-structure of odd-A Sc, F, and Li isotopes is studied within the nuclear shell model framework. It has been observed that the central force possesses strong-orbital node (nl) and weak-spin (j) dependency, and plays a key role in producing changes in proton shell-structure. The integrated effect of proton shell-structure and proton single-particle strength in building the level structure of 49,53,55Sc, 23,25F, and 9 Li isotopes are also discussed. Proton single-particle strength in the level structure of above-mentioned nuclei is studied using proton-transfer spectroscopic factors. It has been particularly discerned that the low energy of the 3 2 − 1 state of 55Sc is caused by the weakening of the N = 34 semimagic gap, the high energy of the 1 2 + 1 state of 23F is originated from an increase in the energy gap between orbitals π1s1/2 and π0d5/2 at N = 14, and the high energy of the 1 2 − 1 state of 9 Li is originated from the large energy gap between π0p1/2 and π0p3/2 orbitals which remained nearly constant from 5 Li to 9 Li.