Nuclear Structure Studies in the Z = 50 Region

Abstract

The purpose of this article is to present briefly the state of our knowledge of nuclei in a particular region of the periodic table, namely those nuclei with proton number near fifty. It is natural to group these together. According to our simplest models, their structures are intimately related. They are spherical nuclei, or at least not strongly deformed. The tin isotopes, with Z = 50, are classified as “single-closed-shell nuclei,” since 50 is a magic number, and the differences in their structure are determined completely by differences in the numbers of neutrons in the valence shells. The indium and antimony isotopes (with Z = 49 and 51) have a proton particle or hole in addition to the fifty in the closed shell. There is a close relationship between their structure and that of the tin nuclei as well as relationships between their various isotopes. The shell-model description of nuclei in this region is thus fairly simple, and makes possible detailed microscopic calculations. On the other hand, the even-mass cadmium and tellurium isotopes (Z = 48 and Z = 52, respectively) look experimentally quite different from the single-closed-shell tin isotopes. It is also much more difficult to calculate their structure. For these reasons, the tin, antimony and indium isotopes make an island of nuclei, about fifty in number, whose properties can profitably be discussed as a unit.