INDRA@GSI: collective flow in Au+Au collisions

Abstract Directed flow in symmetric heavy ion collisions has been studied using the 197 Au+  197 Au reactions at incident energies between 40 and 150 A MeV. The reactions have been measured with the 4 π multi-detector INDRA at the GSI facility. In particular, the bombarding energy at which the elliptic flow switches from in-plane to out-of-plane enhancement has been determined to be clearly above 100 A MeV in good agreement with the result obtained by the FOPI Collaboration. The new data also allows to extend the experimental excitation function of v 2 to lower energies.