Damped reaction dynamics in 197Au + 208Pb collisions at 29 MeV/nucleon

Abstract Velocity and angular distributions of neutrons from the reaction 197 Au + 208 Pb at E A =29 MeV were measured in coincidence with charged reaction products. The neutron emission pattern is found to erolve smoothly with atomic number and energy of the coincident fragments, up to the highest degrees of energy dissipation observed. The velocity distribution of neutrons in coincidence with any type of fragment is essentially bimodal and can be understood in terms of sequential emission from fully accelerated primary projectile-like and target-like fragments. A relatively weak nonequilibrium neutron component is also observed. Neutron multiplicities and spectral slope parameters, as well as the deduced emitter velocities indicate consistently that, even for highly dissipative collisions associated with intermediate-mass fragments, the average damping of kinetic energy available in the entrance channel is incomplete.