Stability of Nuclei

The dependence of the interaction between a nucleon and the nucleus on N/ Z was investigated. An estimation of the maximal A/Z is given; this ratio is found to vary between 3 and 3.8. lt is shown that when N equals the number of neutrons in a closed shell the minimal Z discontinuously changes by several units. It is suggested that these jumps in the values of Z/sub min/ upon closure of the neutron shell may be responsible for the considerable abundance of certain isotopes, providing that the synthesis of atomic nuclei occurred in brief neutron bursts. (auth)