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Abstract

A four-dimensional stochastic approach to dynamics of nuclear fission induced by heavy ions was applied to calculations of the fission rate and time of highly excited compound nuclei. The research took into account not only three shape collective coordinates introduced on the basis of the {c, h, α}-parametrization but also orientation degree of freedom (K-state) -spin about the symmetry axis. Overdamped Langevin equation was used to describe the evolution of the K-state. Impact of orientation degree of freedom on the fission rate and time of the compound nuclei was studied in detail for the reactions with high-energy projectiles 14 N and 16 O on target nuclei 197 Au, 208 Pb, 232 Th and 238 U. It was revealed that inclusion of the K-state in the dynamical model produces considerable increase in the mean fission time and decrease in the stationary fission rate. The K-state impact on the fission rate and time almost fully canceled the opposite effect produced by inclusion of nuclear neck and mass-asymmetry coordinates in the 1D Langevin calculations. The difference of 5-25% between 4D and 1D calculations was found as the result of this research.

Four-dimensional Langevin dynamics of heavy-ion-induced fission

“…This means that the driving force in fission direction in 4D is weaker than the one in 3D, which in turn leads to smaller fission rates and, correspondingly, to larger mean fission times [80][81][82].…”

Simulation of the fission dynamics of the excited compound nuclei 206 Po and 168 Yb produced in the reactions 12 C+ 194 Pt and 18 O+ 150 Sm

“…The particle emission width of a particle of kind ν can be calculated by [40] (17) where s ν is the spin of the emitted particle ν and m ν is its reduced mass with respect to the residual nucleus. E int and B ν are the intrinsic energy and the separation energy of particle ν, respectively.…”

A dynamical interpretation of fusion–fission reactions using four-dimensional Langevin equations

“…Three-dimensional Langevin equations have been used to study the mass and the kinetic energy distribution of fission fragments with a different structure and alternate statistical methods [26]. Four-dimensional [32,33] Langevin equations with a constant dissipation coefficient for the orientation degree of freedom (K coordinate) were applied to calculate different aspects of fusion-fission reactions. Recently, quantum molecular dynamics have been applied to investigate heavy-ion collisions [34][35][36].…”