Energy and pairing dependence of dissipation in real-time fission dynamics

Abstract: This work presents a microscopic study of dissipation in fission dynamical evolutions with the time-dependent Hartree-Fock+BCS method in terms of energy dependence and pairing dependence. The friction coefficients and dissipation energies are extracted by mapping the symmetric fission process of $^{258}$Fm into a classical equation of motion. Density-constrained calculations are used to obtain the dynamical potential. The obtained friction coefficients have a strong dependence of deformations, and averagely match the coefficients adopted in statistical models. The dissipation indeed increase with increasing initial excitation energies or with decreasing pairings. It is also shown that post-scission dissipations play a significant role. The demonstrated characteristics of dissipations will be valuable for calibrations of various fission models.