Effective nuclear interactions

Abstract

The energy level spectra of O¹⁷, O¹⁸, O¹⁹ and O²⁰ are analysed in the framework of the nuclear shell model. The matrix elements of the effective interaction in various two-particle states are deduced. It is shown that the singlet even interaction is not only short-ranged and attractive, but also contains a strongly repulsive central region. This demonstration of a repulsive non-singular core is the essential conclusion of this paper. It is also suggested that it may not be possible to represent the effective triplet odd interaction by a simple central potential. An experimental determination of the 3⁺ state in O¹⁸ would throw further light on this question. The excitation energy of this state is predicted.