Transitional features observed in the charge and angular distributions of deeply inelastic fragments produced in the reaction 181Ta + 620 MeV 86Kr

Abstract

Charged fragments produced in the reaction 181Ta + 620 MeV 86Kr have been studied with ΔE- E telescopes. Kinetic energy spectra, charge distributions and angular distributions have been measured for atomic numbers in the range 13 ≦ Z ≦ 49. For all observed atomic numbers and for all angles, the energy spectra show the presence of energetically relaxed products in the vicinity of the Coulomb barrier. The spectra for elements near the projectile also show a large contribution from incompletely damped events at angles close to the grazing angle. For these elements the spectra show no clean separation between the relaxed and partially damped components. The charge distributions peak at or slightly above the projectile Z. For elements well removed in Z from the projectile, the angular distributions are forward peaked, whereas elements near Kr have angular distributions which are side peaked. The transition from side peaking to forward peaking takes place over a smaller range of Z-values than was observed for the reaction 197Au + 620 MeV 86Kr. The experimental data are interpreted within the framework of a diffusion model. Angular distributions calculated with the diffusion model are in semi-quantitative agreement with experiment. The coupling between energy dissipation and mass transfer is also discussed.