Shell Evolution around and beyond N=28 Studied with Large-Scale Shell-Model Calculations

The evolution of the shell structure around N = 28 is described by the shell-model calculation using an effective interaction based on the monopole-based universal interaction. Performing shell-model calculations, we successfully describe the configuration mixing and deformation from which the shell evolution in this region is well clarified. The reduction of the proton spin-orbit splitting from N = 20 to 28 is dominated by the tensor force and is quantitatively reproduced well in terms of the distribution of the spectroscopic factors. This reduction also brings about a large oblate deformation in Si-42. The location of the neutron 0(g9/2) orbit in Ca isotopes is identified by their 3(1)(-) states.