Pairing Effect in Nuclei

Abstract

It has been previously pointed out by Suess and Kowarski that near the closed neutron shells $N=50$ and $N=82$ the pairing energy of protons is greater than that of neutrons. Glueckauf found the same situation existing in heavy nuclides. Kohman has suggested that this effect may be fairly general in the region of medium-weight and heavy nuclides; however, several regions in which the effect is in the opposite direction have also been reported. On the basis of a generalized atomic mass equation for odd-$A$ nuclides, we have calculated the function $\ensuremath{\epsilon}$ defined by Kohman as the difference between proton pairing energy $\ensuremath{\pi}$ and neutron pairing energy $\ensuremath{\nu}$. It turns out that Kohman's suggestion seems to be in the right direction but with a restricted sense. A theoretical explanation consistent with the assumptions proposed by Mayer for the $j\ensuremath{-}j$ coupling single-particle model has been investigated. The effect on this explanation of the absence of odd-proton isomerism for $63lZl82$ has also been discussed.