Influence of the impact parameter on element distributions in dissipative heavy-ion collisions

The 209Bi+136Xe reaction at laboratory bombarding energies of 940, 1130, 1422 MeV is intrepreted on the basis of a phenomenological classical model and a diffusion model for damped collisions. Initial angular momenta, interaction times, and charge diffusion coefficients are deduced with the above models from experimental data reported previously. The bombarding energy dependence of the model parameters and the effect of deformation on the dinuclear system in the exit channel are discussed. An analytical relation is suggested between the variance sigma/sub Z//sup ts2/ of the element distribution and the ratio E/l/sub g/, where E is the measured final total kinetic energy and l/sub g/ is the grazing orbital angular momentum. This semiempirical formula is applied to sixteen heavy-ion systems at bombarding energies well above the Coulomb barrier. In a plot of lnsigma/sub Z//sup ts2/ versus E/l/sub g/ all the experimental data fall on parallel lines with displacements that are reasonably well correlated with E0/l/sub g/, where E0 is the bombarding energy in the c.m. system. In a model-dependent explanation of this empirical relation, evidence is found that the variance of the element distributions sigma/sub Z//sup ts2/ is determined by the initial relative angular momentum l/l/sub g/