FRAGMENT PRODUCTION IN PERIPHERAL HEAVY ION COLLISIONS AT FERMI ENERGIES IN TRANSPORT MODELS

Abstract

A study of fragment production in peripheral nuclear collisions at Fermi energies with a transport model (Boltzmann–Nordheim–Vlasov, BNV) is presented. It is compared to an experiment for the reaction 18 O on 181 Ta at E/A = 35 MeV measured at very forward angles. The data are decomposed empirically into a two-component structure, one centered at beam velocity ("direct component") and one at lower velocities ("dissipative component"). It is seen that BNV calculations describe the general features of the dissipative component of the reaction. The direct component of experimental data is interpreted with the Goldhaber model, and the width parameter is extracted. We also include the deexcitation of the excited, primary projectile–like residues due to statistical decay to be able to compare the results of calculations more in detail with experiment. This secondary evaporation is important for both isotope and velocity distributions, but a more consistent estimate of the excitation energy of the residues has to be persued.