Cluster correlations in multifragmentation

The possibility of strong cluster correlations in multifragmentation reactions is explored based on the antisymmetrized molecular dynamics calculations. The number of emitted protons, which is smaller than predicted by usual transport models, can be explained by introducing the two-nucleon collision process to the final states in which one or both of the scattered nucleons may form clusters (such as deuterons, tritons and α particles) with other nucleons in the system. The cluster correlation has strong impacts on the whole collision dynamics. The multifragmentation data at 50 MeV/nucleon and above are well reproduced with this strong cluster correlation if pairs of clusters with small relative velocities are assumed to form light nuclei such as Li and Be isotopes. An analysis is shown on symmetry energy effects in emission of nucleons and clusters.