Non-thermal projectile breakup due to friction forces

Abstract Correlations between α particles and weakly damped projectile-like fragments from 26A MeV 32 S + 197 Au have been measured in order to check a semi-microscopic model for mechanical projectile break-up in an ejectile velocity regime extending to high velocities where competing emission by hot intermediate sources can be discarded. After subtraction of sequential-decay contributions, qualitative and/or quantitative agreement of the data, including the dependence on fragment Z, with the model predictions is obtained. The mechanism naturally yields particles also at intermediate emission velocities entering the disputed hot-source parametrizations.