Effective interactions and energy spectra for N =28, 29 and 30 nuclei

A two-range central-plus tensor potential is assumed for the effective nucleon-nucleon interactions in the shell-model calculation of N =28, 29 and 30 isotones. A model space of fsub(7/2)sup(n-1), (psub(3/2,)psub(1/2,) fsub(5/2)] is assumed for the proton configuration of N = 28 nuclei. The correct isospin wavefunctions proposed by Osnes (Nucl. Phys.; A154; 353 (1970)) are considered. For N = 29 and 30 nuclei, the protons are restricted to the lfsub(7/2) orbit, and the valence neutrons are allowed to distribute in the 2psub(3/2,) 2psub(1/2) and lfsub(5/2) shells. Energy level spectra for N =28, 29 and 30 nuclei are calculated in a Talmi-type calculation. The calculated results are in good agreement with the experimental observations. (author)