Microscopic study of the octupole degree of freedom in the radium and thorium isotopes with gogny forces

Abstract

The octupole degree of freedom of the nuclei 218–230Ra and 222–230Th is investigated in a microscopic way. Our analysis is based on the constrained Hartree-Fock plus BCS theory as well as on the adiabatic time-dependent Hartree-Fock in the cranking approximation (and generator coordinate method plus mean field). In the numerical applications we use the Gogny forces. From the mean field calculations we show octupole barrier heights, dipole moments as well as the values of β 2, β 4,β 5, β 6, and β 7 along the constrained path. From the symmetry conserving calculations we display the 0 +–1 − splitting, wave functions as well as the El and E3 transition probabilities. The overall agreement with the available experimental data is very good.