Seniority and (9/2)n configurations in neutron-rich Nickel isotopes

Excited states in low-energy spectra of Ni70-76 are considered. Accordingly, pairing forces in the form of surface delta interaction are employed to account for the formation of the ground state multiplet with seniority nu = 2 states. The multiplet splitting is described with mass relationships of masses of neighboring nuclei. Subsequently, the seniority model is adopted to reproduce or predict the states nu = 3 in odd-even isotopes and nu = 4 in even-even isotopes. The correct account of the 2(1)(+) state should allow for the description of the reversed order of J = 4 states with nu = 2 and nu = 4 observed in experiments. The results obtained are compared with the structure of similar multiplets in N = 50 isotones.

Automated summary

This study investigates excited states in the low-energy spectra of Ni70-76. It employs pairing forces in the form of surface delta interaction to explain the formation of the ground state multiplet with seniority nu = 2 states. The splitting of the multiplet is described using mass relationships of neighboring nuclei. The seniority model is then used to reproduce or predict specific states in odd-even isotopes and even-even isotopes. The results are compared with the structure of similar multiplets in N = 50 isotones.