Pre-Cluster Dynamics In Multifragmentation

The initial production and dynamical expansion of hot spherical nuclei are examined as the first stage both in the projectile-multifragmentation and in central collision processes. The initial temperatures, which are necessary for entering the adiabatic spinodal region, as well as the minimum temperatures and densities, which are reached in the expansion, significantly differ for hard and soft equations of state. Additional initial compression, occurring in central collisions leads most likely to a qualitatively different multifragmentation mechanism. Recent experimental data are discussed in relation to the results of the proposed model.