Systematic study of near yrast band structures in odd-mass $^{125-137}$Pr and $^{127-139}$Pm isotopes

TL;DR

This study extends the triaxial projected shell model to include multi-quasiparticle configurations, enabling detailed analysis of high-spin band structures in odd-mass Pr and Pm isotopes up to the second band crossing.

Contribution

The paper introduces an expanded basis in the shell model approach to better understand high-spin phenomena in odd-mass isotopes, revealing changes in band crossing configurations with increasing neutron number.

Findings

Band crossings involve one-proton and two-neutron configurations in lighter isotopes.

Three-quasiparticle configurations become energetically favored in heavier systems at high spin.

Predicted gamma-band structures based on quasiparticle states.

Abstract

In the present work, the basis space in the triaxial projected shell model approach is expanded to include three and five quasiparticle configurations for odd-proton systems. This extension allows to investigate the high-spin band structures observed in odd-proton systems up to and including the second band crossing region, and as a first major application of this development, the high-spin properties are investigated for odd-mass $^{125-137}$Pr and $^{127-139}$Pm isotopes. It is shown that band crossings in the studied isotopes have mixed structures with first crossing dominated by one-proton coupled to two-neutron configuration for the lighter isotopes which then changes to three-proton configuration with increasing neutron number. Further, $\gamma$-bands based on quasiparticle states are also delineated in the present work, and it is predicted that these band structures built on three-quasiparticle configurations become favoured in energy for heavier systems in the high-spin region.