Formation of Superconducting Pair Correlations in Spherical Even-Even Nuclei

The occurrence of like-nucleon pair correlations in the ground state of spherical even-even nuclei is considered on the basis of the special Bogoliubov transformation. It is confirmed that, in closed-subshell nuclei, superconducting pair correlations occur at coupling constants G greater than a certain threshold value. Rough estimates of upper and lower bounds are obtained for the threshold value. It is shown that, in open-subshell nuclei, superconducting correlations exist at any positive G, and nucleon pairs are distributed over all subshells participating in the pairing interaction.