Experimental data obtained with the 4$\pi$ multidetector system INDRA are used to study the light charged particle (LCP, $Z<~$2) and intermediate mass fragment (IMF, $Z>~$3) production in peripheral and semicentral collisions of Xe and Sn at 50 MeV/nucleon. It is found that a sizable fraction of the detected LCP’s and IMF’s originates from the midvelocity region. These fragments can be seen to come either from a prompt (preequilibrium) mechanism or from a slower but dynamically influenced emission process. The relative magnitude of the dynamically influenced emission relative to the isotropic statistical evaporation is presented as a function of the transverse energy of light particles, used as an impact parameter selector. The results are compared to dynamical models with which a good agreement is obtained.

• Received 6 November 1996

DOI:https://doi.org/10.1103/PhysRevC.55.1906