Decrement of Spin-orbit Splitting Near Calcium Region

Abstract

Explanation of the observed decrement of splitting of spin-orbit partners near shell closure, has been sought through an introduction of tensor interaction in a mean field type of calculation.    The strength of the tensor interaction used in the Skyrme Hartree Fock theory has been optimized by the reproduction of the experimentally determined splitting of 1d, 1f and 2d shell model states (both neutron and proton) of the isotopes of Calcium (40,48) and Nickel-56. Due to two large shell gaps and availability of experimental data in the Calcium region, the change in the splitting of the neutron as well as the proton shell model 1f and 2p states of the nuclei near Calcium have been evaluated and compared with the experiment. It appears that the splitting of spin-orbit doublets decreases for proton (neutron) states near the Fermi surface with the increase of neutron (proton) numbers for these nuclei vindicating the importance of tensor interaction in explaining the observed decrease.