Internal excitation of intermediate mass fragments from collisions of Ar36+Ag nuclei at 35 MeV/nucleon

Population rates for neutron-unbound states compared to bound states were determined for intermediate mass fragments from Ar36+Ag collisions at 35 MeV/nucleon. The population ratios were measured as a function of fragment kinetic energy at angles of 15°, 30°, 45°, and 60°, especially for B12 fragments but also for Li7, Li8, Be11, and C13 fragments. The results show no major dependence on either the kinetic energy or the emission angle of the fragments. There are signs of a moderate contribution to the dominating statistical decay from nonequilibrium quasi-elastic decay at the smaller angles. The population ratios for the different fragments are consistent with emission from a source of a single temperature which emits complex nuclei at freeze-out. Comparison of the present results with those from a similar experiment, but with N14 projectiles at 35 MeV/nucleon, shows that the population ratios for strongly damped processes are the same for both N14 and Ar36 projectiles on Ag.