Multifragmentation after multi-ionization of hydrogen clusters in high energy cluster-atom and cluster-cluster collisions

We report on a cluster fragmentation study involving collisions of high-ene rgy hydrogen cluster ions with atomic helium or fullerenes. The experimenta l characterization of the cluster fragmentation, not only by the average fr agment size distribution but also by a statistical analysis of the fragment ation events, has become possible because of a recently developed multicoin cidence technique in which all the fragments of all the collisions occurrin g in the experiment are mass analyzed on an event by event basis. From the breakup in two fragments to the complete disintegration of the cluster, the fragmentation phenomenon exhibits a transition with an increase of the flu ctuations. The fragmentation events with more than one H-3(+) fragment evid ence the cluster multifragmentation process. An important aspect of these r esults is that high-energy cluster collision can induce a reaction in the c luster. (C) 1999 Elsevier Science B.V.