Angular evolution of peripheral heavy ion reactions at intermediate energies

Abstract

Energy spectra and angular distributions of projectile-like fragments have been measured in the vicinity of the grazing angle for the 40Ar + 40Ca and 40Ar + 208Pb reactions at 44 MeV/nucleon. Measurements of the 40Ar + 40Ca system at 27 MeV/nucleon and 20Ne + 208Pb reaction at 44 MeV/nucleon at one angle have also been performed. For fragments with charge and mass close to the projectile numerous deviations from the standard fragmentation model have been observed including rapidly changing shapes of the angular distributions with the fragment mass. Moreover the isotopic distributions and mean fragment velocities are strongly dependent on detection angle. A surface transfer reaction component dominant at the grazing angle can be separated from a second component which cannot be entirely accounted for by a simple fragmentation mechanism.