Transition from in-plane to out-of-plane azimuthal enhancement in Au plus Au collisions

The incident energy at which the azimuthal distributions in semicentral hea vy-ion collisions change from in-plane to out-of-plane enhancement - E-tran is studied as a function of mass of emitted particles, their transverse mo mentum and centrality for Au + Au collisions. The analysis is performed in a reference frame rotated with the sidewards flow angle (Theta (flow)) rela tive to the beam axis. A systematic decrease of E-tran as function of mass of the reaction product s, their transverse momentum and collision centrality is evidenced. The predictions of a microscopic transport model (IQMD) are compared with t he experimental results. (C) 2001 Elsevier Science B.V. All rights reserved .