A critical analysis of the modelling of dissipation in fission

Abstract

Abstract:The time-dependent flux over the fission barrier of an excited nucleus under the influence of dissipation is investigated. Characteristic features of the evolution of the amplitude of the probability distribution and the velocity profile at the fission barrier are derived. Analytical results are compared to numerical Langevin calculations and used to develop a new analytical approximation to the solution of the Fokker-Planck equation for the time-dependent fission-decay width. This approximation is shown to be more realistic than previously proposed descriptions, which were widely used in the past..

Macroscopic-microscopic approach to the nuclear fission process

“…For excitation energies above the corresponding threshold also break-up and the simultaneous emission of several fragments is considered [22]. Fission is treated as a dynamical process, taking into account the role of dissipation in establishing quasi-equilibrium in the quasibound region by the implementation of a time-dependent fission-decay width [23] with a proper description of the initial conditions included [24]. When the system passes the fission barrier and proceeds to fission, it is characterised by mass and atomic number, excitation energy and angular momentum.…”

Recent Achievements In Fission Dynamics Investigated At High Energies

“…The fission probability is computed according to a timedependent fission width following the analytical description of the solutions of the corresponding Fokker-Plank equation proposed in Refs. [27,28,29]. The code also allows to evaluate the fission width according to the transition-state model of Bohr and Wheeler [30] or the time-independent formulation of Kramers [3].…”

New experimental approaches to investigate the fission dynamics

“…The fission probability is computed according to a time-dependent fission width following the analytical description of the solutions of the corresponding Fokker-Plank equation proposed in Refs. [24,11,25]. The code also allows to evaluate the fission width according to the transition-state model of Bohr and Wheeler [1] or the time-independent formulation of Kramers [2].…”