Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV

Zbiri, K.; LeFèvre, A.; Aichelin, J.; Łukasik, J.; Reisdorf, W.; Gulminelli, F.; Lynen, U.; Müller, W. F. J.; Orth, H.; Schwarz, C.; Sfienti, C.; Trautmann, W.; Turzó, K.; Zwiegliński, B.; Auger, G.; Charvet, J. L.; Chbihi, A.; Dayras, R.; Durand, D.; Frankland, J. D.; Legrain, R.; Neindre, N. Le; Lopez, O.; Nalpas, L.; Parlog, M.; Rivet, M. F.; Rosato, E.; Vient, E.; Vigilante, M.; Volant, C.; Wieleczko, J. P.

Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV

Authors

Description

Using the quantum molecular dynamics approach, we analyze the results of the recent INDRA Au+Au experiments at GSI in the energy range between 60 AMeV and 150 AMeV. It turns out that in this energy region the transition toward a participant-spectator scenario takes place. The large Au+Au system displays in the simulations as in the experiment simultaneously dynamical and statistical behavior which we analyze in detail: The composition of fragments close to midrapidity follows statistical laws and the system shows bi-modality, i.e. a sudden transition between different fragmentation pattern as a function of the centrality as expected for a phase transition. The fragment spectra at small and large rapidities, on the other hand, are determined by dynamics and the system as a whole does not come to equilibrium, an observation which is confirmed by FOPI experiments for the same system.
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