Microscopic study of positive-parity yrast bands of 224−234Th isotopes

Abstract

The positive-parity bands in 224 − 234Th are studied using the projected shell model (PSM) approach. The energy levels, deformation systematics, B(E2) transition probabilities and nuclear g-factors are calculated and compared with the experimental data. The calculation reproduces the observed positive-parity yrast bands and B(E2) transition probabilities. Measurement of B(E2) transition probabilities for higher spins and g-factors would be a stringent test for our predictions. The results of theoretical calculations indicate that the deformation systematics in 224 − 234Th isotopes depend on the occupation of low k components of high j orbits in the valence space and the deformation producing tendency of the neutron–proton interaction operating between spin orbit partner (SOP) orbits, the [(2g9/2) π –(2g7/2) ν ] and [(1i13/2) π –(1i11/2) ν ] SOP orbits in the present context. In addition, the deformation systematics also depend on the polarization of (1h11/2) π orbit. The low-lying states of yrast spectra are found to arise from 0-quasiparticle (qp) intrinsic states whereas the high-spin states turn out to possess composite structure.