Self-organization in expanding nuclear matter

Within a nuclear molecular dynamics model we study the conditions for the formation of nuclear clusters in expanding highly excited nuclear systems. A simple backtracing method for early cluster recognition is introduced. It is demonstrated that most clusters are formed in a self-organization process bringing together nucleons which were initially far separated in the phase space. The cluster environment always contains fast nucleons responsible for the local cooling in the creation process. In an example of heavy ion collision we observe two groups of clusters associated with rupture-like and coalescence-like processes.