Prominent transverse flow of clusters in stopped Au (150 A MeV) + Au reactions

Abstract Stopped Au (150 A MeV) + Au collisions have been measured with the FOPI-Detector at GSI by imposing an upper limit on the ratio of the global longitudinal momentum to the collected charge within an event. The ejectiles, in particular those with Z >3, have a rapidity close to mid-rapidity and exhibit angular distributions in the centre-of-mass strongly peaking around 90° thus suggesting an enhancement of the flow in the transverse direction. Fits to the data and comparisons with QMD calculations indicate an averaged collective velocity in the transverse direction equal to 0.12 c . Significance of the determined velocity and temperature values is discussed.