Mechanism of Statistical Nucleosynthesis in Rapidly Expanding Nuclear Matter

Abstract

Formation of intermediate mass and light nuclei in the excited and rapidly expanding nuclear matter is investigated. We demonstrate that this phenomenon can be explained within the statistical approach by applying the concept of local equilibrium. We subdivide the expanding nuclear system into several parts (primary clustering), consisting of nucleons, close in phase space. Inside these primary clusters the process of nucleation takes place, which can be described as the statistical decay of such clusters in the coexistence region of nuclear liquid-gas phase transition. Within this approach one can explain simultaneously both yield and kinetic (flow) energy of the produced nuclei, that wasn’t possible when considering global chemical equilibrium in the whole nuclear system. We believe that our approach can be a generalization of the freeze-out volume concept, developed for multifragmentation reactions at high energy. The influence of isospin on the process is investigated. The mechanism of such a production of nuclei, including exotic nuclear species, can be realized in central collisions of heavy ions at intermediate energies.