Cluster Emission in Complex Nuclear Reactions

Abstract

Abstract. Possible mechanisms of the emission of nuclear clusters in heavy-ion induced nuclear reactions are discussed in the context of the overall dissipative reaction environment. Essentials of model approaches to the reaction dynamics are briefly reviewed. Analysis of the overall reaction dynamics provides an estimate of time scales for cluster emission and the buildup or preexistence of nucleonic correlations. Experimental results demonstrate the presence of at least two different mechanisms of cluster emission. Energetic nuclear clusters are likely emitted during early stages of a nuclear reaction, containing memory of entrance-channel conditions. In addition, sequential, statistical cluster emission is observed from the hot remnants of projectile and target nuclei. The difficulty encountered previously by statistical models to describe statistical emission of massive clusters from excited nuclei is resolved in the framework of a simple interacting Fermi-gas model of expanded nuclear matter. It is suggested that sequential cluster emission is entropydriven and can be understood in terms of a rearrangement of the surface of hot nuclei produced in energetic nuclear reactions.