Odd-mass nickel isotopes in a generalized-seniority approach

The nickel isotopes exist over a wide range of neutron numbers, extending from proton-rich to very neutron-rich nuclei. Here we report a consistent study of the odd-mass Z=28 nuclei in the full pf+g(9/2) shell using the generalized-seniority shell model. We include up to three unpaired nucleons in the odd sector, and up to two in the even sector. We also report related results for the odd-mass Cu-69 and odd-odd Co-66 nuclei. Our calculations make use of a realistic shell-model interaction, whose monopole part has been renormalized to fit the properties of nuclei near closed shells. The calculated results are in good global agreement with experimental data, and contain some evidence of the persistence of the N=40 subshell closure around Ni-68. The results demonstrate the importance of keeping the entire pf+g(9/2) space as active, both for neutrons and protons.