n-p interaction in odd-odd nuclei and odd-Alpha nuclei

The interaction energies of the last i proton(s) and the last i neutron(s) were obtained from nuclear mass-data-base. The last n-p interaction energy epsilon(1p-1n) of odd-odd nuclei was compared with half of the average value of the last proton-dineutron interaction energy epsilon(1p-1n) in odd-Z nuclei and the last diproton-neutron interaction energy epsilon(2p-1n) in odd-N nuclei. It is found that the former is systematically greater than the latter. The enhancement of n-p interaction may be attributed to the effect of pairing weakening the n-p interaction in. odd-A nuclei as well as GM shifts. Additionally, it is found that epsilon(1p-2n) in odd-Z nuclei is generally approximate to epsilon(2p-1n) in odd-N nuclei with the same mass number A, which is equivalent to the Garvey-Kelson mass relation.