Reaction dynamics and “hyerarchy” effects from light fragments correlations

A review of results for fragments emitted in the reactions 124Sn + 64Ni and 112Sn + 58Niat 35A.MeV,studied using the 4pi Chimera multidetector, is done. In particular different observable like fragment's isotopic composition, transverse and parallel velocity, angular distributionshavebeen correlated asafunction of thecentralityofthecollision for fragments emitted in the mid-velocity zone. A clear signature of fast dynamical emission of light fragments (Z<9) produced in the midrapidity domain has been found characterized by short emission times, larger N/ Z ratio and stronger angular anisotropies respect to particles produced in sequential statis tical emission. For semi-central collisions, preliminary analysis of fragmentation events with two or three particles in the mid-velocity zone shows hierarchy effects in transverse velocities and collective flows, th at could be indication of a boundary between neck fragmentation and the inset of multifragmentation regime.