Fragment flow in Au+Au collisions

Collective effects in Au + Au collisions at bombarding energies going from 100 to 800A MeV have been extensively investigated over the last years with the FOPI apparatus at GSI-Darmstadt. The main experimental results related to the different forms of nuclear matter how in semi-central collisions are presented. The relevance of intermediate mass fragments as a probe of the collision dynamics and the collective motion is illustrated. The centrality dependence of both sideward flow and squeeze-out effects is examined over a broad range of impact parameters. Data are compared to Quantum Molecular Dynamics model predictions for different parametrisations of the nuclear equation of state. The onset of expansion phenomena in heavy-ion collisions is discussed on the basis of extrapolations of the measured excitation functions for both sideward flow and squeeze-out effects.