Abstract
The pairing correlation energy for two-nucleon configurations with the spin-parity and isospin of , and , are calculated with and pairing interactions, respectively. To this end, we consider the -shell-model space, including single-particle angular momenta of and . It is pointed out that a two-body matrix element of the spin-triplet pairing is weakened substantially for the orbits, even though the pairing strength is much larger than that for the spin-singlet pairing interaction. In contrast, the spin-triplet pairing correlations overcome the spin-singlet pairing correlations for the configuration, for which the spin-orbit splitting is smaller than that for the configurations, if the strength for the pairing is larger than that for the pairing by 50 or more. Using the Hartree-Fock wave functions, it is also pointed out that the mismatch of proton and neutron radial wave functions is at most a few percent level, even if the Fermi energies are largely different in the proton and neutron mean-field potentials. These results imply that the configuration with , is likely in the ground state of odd-odd -shell nuclei even under the influence of the strong spin-triplet pairing, except at the middle of the shell, in which the odd proton and neutron may occupy the orbits. These results are consistent with the observed spin-parity for all odd-odd -shell nuclei except for Cu, which has . The magnetic moment of a state is also discussed in order to show a manifestation of the change of the shell-model scheme from coupling to coupling.
- Received 18 December 2012
DOI:https://doi.org/10.1103/PhysRevC.87.034310
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