The Quasi-Spin Scheme

In preceding sections we considered the seniority scheme for jⁿ configurations of identical nucleons. We saw examples where nuclear states may be fairly well approximated by such configurations. We also saw how well predictions of the seniority scheme agree with actual data. There are, however, semi-magic nuclei whose states cannot be described by pure jⁿ configurations. Yet, as we shall see later on, many properties of the seniority scheme are observed also in some cases where there is appreciable configurations mixing. The concept of seniority should then be generalized to include multi-configuration situations.