Different particle alignments in N ≈ Z Ru isotopes studied by the shell model

الأصل · EN

Experimentally observed heaviest N ≈ Z nuclei, Ru isotopes, are investigated by the shell model on a spherical basis with the extended P+QQ Hamiltonian. The energy levels of all the Ru isotopes can be explained by the shell model with a single set of force parameters. The calculations indicate enhancement of quadrupole correlations in the N=Z nucleus ⁸⁸Ru as compared with the other Ru isotopes, but the observed moments of inertia seem to require much more enhancement of quadrupole correlations in ⁸⁸Ru. It is discussed that the particle alignment takes place at 8+ in ⁹⁰Ru but is delayed in ⁸⁸Ru till 16+ where the simultaneous alignments of proton and neutron pairs take place. The calculations present interesting predictions for ⁸⁹Ru that the ground state is the 1/2- state and there are three ΔJ=2 bands with different particle alignments including the T=0 p-n pair alignment.