Relaxation times in dissipative heavy-ion collisions

Abstract

The classical model introduced earlier for analyzing experimental data on dissipative heavy-ion collisions, is generalized to include effects from the gradual dissipation of radial kinetic energy and from the development of fragment deformations during the collision. Relaxation times for the dissipation of radial kinetic energy (τ R ) and relative angular momentum (τ l ) as well as for the development of deformations (τα) are fitted to the reaction86Kr (8.18 MeV/u) +166Er and applied to three other reactions. A consistent set of relaxation times isτ R = 0.3 · 10−21 s,τ l =1.5 · 10−21 s andτ α = 5 · 10−21 s. Empirical mass transport coefficients are deduced from comparisons with experimental element distributions. Effects from fluctuations in the deflection function are discussed. Evidence is found for the existence of a relaxation time of the order 10−21 s in the mass-drift coefficient.