Dynamical Model of Fission Fragment Angular Distribution

The dynamical model of fission fragment angular distributions is suggested. The model allows one to calculate fission fragment angular distributions, prescission light particle multyplicities, evaporation residue cross sections etc. for the cases of decay of hot and rotating heavy nuclei. The experimental data on angular anisotropies of fission fragmenta and neutron multiplicities are analyzed for the ¹⁶O + ²⁰⁸Pb, ²³²Th, ²⁴⁸Cm and ²³⁸U reactions at the energies of the incident ¹⁶O ions ranging from 90 to 160 MeV. This analysis allows us to extract both the nuclear friction coefficient value and the relaxation time for tilting mode. It is also demonstrated that the angular distributions are sensitive to deformation dependence of the nuclear friction coefficient.