Collective motion in selected central collisions of Au on Au at 150A MeV

Using the FOPI facility at GSI Darmstadt complete data of Au on Au collisions at 150A MeV were collected for charged products (Z=1–15) at laboratory angles 1°≤${\mathrm{\Theta }}_{\mathrm{lab}}$≤30°. Central collisions were selected by applying various criteria. The kinetic energy spectra of fragments from an isolated midrapidity source are investigated in detail for center-of-mass angles 25°≤${\mathrm{\Theta }}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$≤45°. The heavy products (Z≥3) are used to determine the collective energy which is found to be at least 10A MeV.