Configuration Assignments to K = 1/2 Three-Quasiparticle Bands

In the present work, configuration assignments to K = 1/2 bandheads of given three-quasiparticle (3qp) quadruplets experimentally observed and yet to be observed in odd-A nuclei lying in the rare-earth mass region are carried out based on an improved version of an earlier empirical formulation. The important contributions of the irrotational component, residual n-p interactions, and rotor–particle coupling terms are explored and highlighted. The magnitude of the RPC term is found to be comparatively smaller (≈5–10 keV) than the irrotational and residual interactions and can affect the 3qp bandheads with small energy separation. We confirm the tentative configuration assignments of three K = 1/2 bandheads having configurations 1/2[411]π⊗7/2[523]π⊗5/2[523]ν and 1/2[411]π⊗9/2[514]π⊗7/2[514]ν in 175Yb and 9/2[514]π⊗7/2[514]ν⊗1/2[521]ν in 177Ta nuclides. The average deviation between experimental data and present model calculations for 175Yb and 177Ta is 37.9 keV and 163.2 keV, as compared to the earlier model estimates, which yielded a deviation of 249.7 keV and 222.3 keV, respectively. We also resolved some issues pertaining to ambiguous configuration assignments of 3qp quadruplets observed in 177Lu, 173Ta, and 179Ta nuclides. Encouraged by the good overall agreement among experimental and calculated bandhead energies, we have extended these calculations to predict the locations of 18 K = 1/2 bandheads, which are members of 3qp quadruplets of 171,175,177Lu, 173,179,181Ta, and 179,183Re nuclides but have not been observed experimentally and will be useful for predicting bandheads associated with various 3qp states.