Dynamical treatment of fission fragment angular distribution

A dynamical approach to the treatment of fission fragment angular distribution is developed. The approach is based on three- dimensional Langevin dynamics for shape collective coordinates joined with the Monte Carlo algorithm for the degree of freedom associated with the projection K of the total angular momentum of the fissioning system on the symmetry axis. The relaxation time of the tilting mode tau(K) is estimated. From fits to experimental data on the fission fragment angular distribution of heavy fissioning compound systems, the K equilibration time is deduced to be similar to 4 x 10(-21) s for temperatures similar to 1-2 MeV. A modified one-body mechanism of nuclear viscosity with the reduction coefficient of the contribution from the 'wall' formula k(s) = 0.25 has been used in calculations.