Study on 222–226Th Isotopes in the Cranking Framework

Abstract

The yrast spectra, quadrupole moments, quadrupole deformation parameters (β 2), non-axiality parameters (γ), root mean-square radii for protons and neutrons, occupation probabilities, moment of inertia (I), and B(E2) transition probabilities are calculated for 222–226Th in the cranked Hartree–Bogoliubov framework. The calculations employ a quadrupole-quadrupole plus pairing model of residual interaction operating in a reasonably large valence space outside the 164Pb core. Our calculations reproduce qualitatively the observed yrast spectra in 222–226Th up to spin 20+. The calculated results indicate that the non-axiality parameter decreases as one moves along the yrast states. The observed increase in deformation from 222Th to 226Th is due to the increase in the occupation of low-k components of $(2g_{9/2})_{\pi }$ and $(1j_{{15/2}})_{\nu }$ orbits. The model parameters reproduce not only the moment of inertia, deformation, and transition probabilities but also the proton and neutron pairing gaps and are the most appropriate for cranking studies in this region.