Langevin description of mass distributions of fragments originating from the fission of excited nuclei

A stochastic approach to fission dynamics is proposed. The approach, which is based on Langevin equations, is used to calculate the mass distributions of fragments originating from the fission of excited nuclei. The effect of viscosity and light-particle emission on the variance of mass distribution s is studied. The results of the calculations based on the above approach r eveal that, in order to obtain a simultaneous description of mass-distribut ion parameters and the multiplicities of prescission particles, it is neces sary to use sufficiently large values of nuclear viscosity both for the one -body and for the two-body viscosity mechanism, anomalously large values of the viscosity coefficient being required in the latter case. (C) 2000 MAIK "Nauka/Interperiodica".