The Interacting Boson Model (IBM) has been employed in the evaluation of the collective contribution to the nuclear level densities. F bosons were considered in order to describe low-lying octupole states, allowing us to calculate first order negative parity contribution to the collective enhancement factor. The temperature dependence of the effective boson number is obtained in the frame of approximate projected BCS model at finite temperature. The method can be applied not only to spherical or well deformed nuclei, but also to transitional ones. Calculations were performed for the transitional thorium isotope chain. Numerical results for Th-232 are compared with phenomenological recipes used in the generalized superfluid model.
Damping of the Collective Enhancement of the Level Density for Thorium Isotopes
Ventura, A.;Mengoni, A.;
2000-06-05
Abstract
The Interacting Boson Model (IBM) has been employed in the evaluation of the collective contribution to the nuclear level densities. F bosons were considered in order to describe low-lying octupole states, allowing us to calculate first order negative parity contribution to the collective enhancement factor. The temperature dependence of the effective boson number is obtained in the frame of approximate projected BCS model at finite temperature. The method can be applied not only to spherical or well deformed nuclei, but also to transitional ones. Calculations were performed for the transitional thorium isotope chain. Numerical results for Th-232 are compared with phenomenological recipes used in the generalized superfluid model.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
