Dynamical and. statistical bimodality in nuclear fragmentation reactions at intermediate energies

International audienceThe phenomenon of liquid-gas phase transition occurring in heavy ion collisions at intermediate energies is a subject of contemporary interest in recent years [1]. The largest cluster is an important order parameter for studying nuclear liquid gas phase transition in intermediate energy heavy ion reactions. It has been proposed [2] that the double humped distribution (hence the name bimodality) of the largest cluster probability in nuclear multifragmentation is a measurable signature of nuclear liquid gas phase transition. But the origin of the experimentally observed bimodality is still not clear. Some recent work shows that it is due to presence of memory effect of entrance channel where thermal equilibrium is not achieved in this energy domain. The signal was interpreted in these studies as a dynamical bifurcation of reaction mechanism, induced by fluctuation of collision rate, which leads to fluctuations of collective momentum distribution [3]. Other successive studies establish the equilibrium scenario of bimodality, which would rather point towards a thermal phase transition [4]. This work focuses on the combined effect of entrance channel and exit channel on bimodality