Effective two body interaction in simple nuclear spectra.

The low-lying spectra of some simple nuclei (two nucleons outside closed shells or the equivalent situations) are analyzed in terms of a force with a short range component, taken to be a delta force, and a long range core-mediated component. Formulas are given for the energy splitting among the members of the resulting multiplets. Both the cases of particles sitting in equivalent as well as in non-equivalent orbits are considered. An estimate of the contribution to the residual effective interaction from the different components of the force is obtained by means of a least fit to the data.