Directed and elliptic flow in Au + Au at intermediate energies
  Directed and elliptic flow for the Au + Au system at incident energies between 40 and 150 MeV per nucleon has been measured using the INDRA 4 pi multi-detector. For semi-central collisions, the elliptic flow of Z <= 2 particles switches from in-plane to out-of-plane enhancement at around 100 MeV per nucleon, in good agreement with the result reported by the FOPI Collaboration. The directed flow changes sign at a bombarding energy between 50 and 60 MeV per nucleon and remains negative at lower energies. The conditions for the appearance and possible origins of negative flow are discussed. 
J. Lukasik, G. Auger, M.L. Begemann-Blaich, N. Bellaize, R. Bittiger,   F. Bocage, B. Borderie, R. Bougault, B. Bouriquet, J...