Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

Abstract

A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision, and mass of the system. The data have been collected with the FIASCO setup in the reactions $^{93}\mathrm{Nb}+^{93}\mathrm{Nb}$ at $(17,23,30,38)A$ MeV and $^{116}\mathrm{Sn}+^{116}\mathrm{Sn}$ at $(30,38)A$ MeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code GEMINI at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences in both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.