A new kind of seniority isomers, and their consequences

The interest in studying “Nuclear Isomers” from all over the world has increased over the last few decades due to their importance in exploring nuclear structure and various other possible applications. A large amount of experimental data is now available. A keen yet patient eye on nuclear isomers and their properties has led to a tabulation of more than 2500 isomers in our “Atlas of Nuclear Isomers”. The data provide many systematic features to explore on. Seniority is a beautiful concept due to the pairing of nucleons in nuclei, and explains many interesting features and phenomena; one of them is the emergence of seniority isomers. We have recently extended this seniority picture in single-j to the generalized seniority scheme in multi-j, and successfully established a new set of seniority selection rules in the mixed configurations. One of the important findings is to achieve a new kind of seniority isomers, odd tensor decaying ones for the first time. This new set of selection rules explains the known experimental data for various mass regions remarkably well, and predicts some unknown numbers for the gaps in the experiments. In short, the generalized seniority works as a reasonably good quantum number for a set of states, particularly in semi-magic nuclei. We demonstrate that the generalized seniority plays a connecting key for all the mass regions throughout the nuclear chart and leads to the similarities among them, while the involved valence spaces, orbitals, and nucleons are totally different.