Intermediate energy heavy ion reactions

Abstract

The intermediate energy heavy ion induced reactions are extensively studied for several years. In this paper, we try to summarize the present knowledge. The peripheral reactions appear to be intermediate between the fragmentation and the deep inelastic regimes. Many questions remain open concerning the energy relaxation mechanisms and an eventual participant zone creation. In the case of central collisions, it has been shown that very hot nuclei can be built. The fusion limits are discussed and the very hot nuclei properties are considered. In some cases, hot spot formation or compression effects could play a role. Multifragmentation is discussed as a possible decay channel. In all these aspects, a difficult question concerns the validity of the temperature concept and more generally of collective thermodynamical variables. Such collective effects have been investigated in pion production experiments.