Abstract
Garrett et al. systematically investigated band-crossing frequencies resulting from the rotational alignment of the first pair of neutrons (AB) in rare-earth nuclei. In that study, evidence was found for an odd-even neutron number dependence attributed to changes in the strength of neutron pairing correlations. The present paper carries out a similar investigation at higher rotational frequencies for the second pair of aligning neutrons (BC). Again, a systematic difference in band-crossing frequencies is observed between odd- and even- Er, Yb, Hf, and W nuclei, but in the BC case, it is opposite to the AB neutron-number dependence. These results are discussed in terms of a reduction of neutron pairing correlations at high rotational frequencies and of the effects of Pauli blocking on the pairing field by higher-seniority configurations. Also playing a significant role are the changes in deformation with proton and neutron numbers, the changes in location of single-particle orbitals as a function of quadrupole deformation, and the position of the Fermi surface with regard to the various components of the neutron shell.
- Received 22 March 2019
DOI:https://doi.org/10.1103/PhysRevC.100.014302
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