Event shape analyses of intermediate energy symmetric system. Heavy ion collisions

Event shape analyses have been performed on a comprehensive set of experimental data from symmetric system (20Ne+27Al, 40Ar+45Sc, 84Kr+93Nb, and 129Xe+139La) collisions, each system being measured systematically over a wide range of (intermediate) beam energies. The average shapes of events, via e.g., the open-quotes sphericityclose quotes and open-quotes coplanarityclose quotes variables, are shown as functions of the system mass, beam energy, centrality condition, severity of the centrality cut, and, for each of these, for all or certain subsets of the particles measured event by event. Dramatic differences in the average event shapes obtained under different centrality conditions, as well as dramatic differences between the shapes of light particle emission and intermediate mass fragment (IMF) emission, will be described. The system mass and beam energy dependence of the average shapes of the IMF emission which will be shown to be indicative of the importance of so-called open-quotes simultaneous multifragmentationclose quotes processes, are also described