FRAGMENTATION IN CENTRAL PB+AU COLLISIONS WITHIN A MICROSCOPIC DYNAMIC APPROACH

The prompt fragmentation of a very massive nuclear system obtained in heavy-ion collisions at intermediate energies is studied in the framew ork of the semi-classical Landau-Vlasov model taking into account the two-body residual interactions and the isospin dependence. In a first phase, compression and expansion take place. In a second stage, the st rong Coulomb repulsion and neutron-proton asymmetry lead to the format ion of an evanescent bubble-like configuration which decays rapidly in to several fragments. Time evolution of the densities and energy compo nents as well as dependence on the beam energy are particularly analyz ed. Quantitative comparisons are made with experimental data obtained in the Pb-208(29 MeV/u) + Au-197 reaction.