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Observed rotational bands that terminate or appear to terminate at very high spin are analyzed within the configuration constrained cranked Nilsson-Strutinsky (unpaired CNS or CNSB with pairing) formalism. Spin values for the nuclei discussed reach or come close to the maximum spin that can be built within the Z,N=50–82 shells. Configurations are distinguished not only by the number of particles in high-j and low-j shells within each N shell but, in some cases, also by the number of particles in pseudospin partners like d5/2g7/2 and s1/2d3/2. Configurations in Dy156 and Hf164, which terminate at I≈60, are well understood in terms of their occupation of open j shells or groups of j shells. The bands in Dy156 are tentatively observed up to termination while the bands in Hf164 are still a few spin units away. These terminating states are built with up to 18 aligned particles or 18 particles+holes outside a core. The core is built from nucleons in filled j shells, which gives no contribution to the spin. Analysis of the high-spin bands in Xe125,126 and Ce131,132 suggests that bands in Xe126 and Ce132 are observed to terminate at similar spin values, where terminating bands in Xe126 are observed high above yrast. It is remarkable that the deformed mean field, plus single-particle configurations, is able to provide such a comprehensive description of known experimental levels in nuclei up to spin 60ℏ and beyond. It is also impressive that the model can relate alignments of single-particle spin vectors to changes in shape with the nuclear spin. Published by the American Physical Society 2024
Ragnarsson et al. (Thu,) studied this question.