Probing midrapidity source characteristics with charged particles and neutrons in the Cl-35+Ta-nat reaction at 43 MeV/nucleon

The characteristics of the midrapidity and target sources (apparent tempera tures, velocities, and neutron multiplicities) extracted from the neutron e nergy spectra, have been measured for various quasiprojectile (QP) excitati on energies, reconstructed from char ed particles of well defined periphera l events in the Cl-35 + Ta-nat reaction at 43 MeV/nucIeon. The reconstructe d excitation energy of the QP is always smaller than the excitation energy calculated from its velocity, assuming pure dissipative binary collision. T he latter observation combined with the neutron multiplicity at midrapidity and the apparent temperature suggests important preequilibrium and/or dyna mical effects in the entrance channel. The midrapidity source moves at a ve locity lower than the nucleon-nucleon center of mass velocity showing the i mportance of the attractive mean-field potential from the target even at 43 MeV/nucleon. The above picture is confirmed by comparison to Boltzman-Nord heim-Vlasov (BNV) simulations. [S0556-2813(99)50302-6].