Angular momentum transfer and energy loss in the 32S + 60,64Ni peripheral reactions at 160.5 MeV

Abstract

The first two moments of the γ-ray multiplicity distribution have been measured as a function of the energy of projectile-like fragments ( Z = 14−16) for the reactions 32S + 60,64Ni at 160.5 MeV lab bombarding energy. The increase of both moments with increasing total kinetic energy loss exhibits a plateau above ~15 MeV, which seems to be correlated with a shape evolution of the angular distribution taking place around the same energy. Anomalously large relative widths of the γ-multiplicity have been observed also at large energy losses. The trends of 〈M〉 and σ M for small energy losses are well described within the time-dependent shell model for the nucleus-nucleus collision, while discrepancies are observed at large energy losses where features of direct and damped processes seem to coexist.