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HK: Physik der Hadronen und Kerne

HK 41: Heavy Ions IV

HK 41.2: Group Report

Thursday, March 11, 2004, 14:00–14:30, E

Nuclear Stopping at SIS Energies - Results from FOPI — •Olaf Hartmann — Gesellschaft für Schwerionenforschung mbH, Darmstadt, Germany

We present a complete systematics (excitation function and system-size dependence) of global stopping for heavy ion reactions in the energy range between 90A MeV and 1.93A GeV studied with the FOPI detector. For the heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 200A to 800A MeV with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amout of sideflow. Isospin tracing experiments at 0.4A and 1.5A GeV using the system ⁹⁶Ru/⁹⁶Zr and an analysis of the asymmetric reaction ⁴⁰Ca+¹⁹⁷Au at 1.5A GeV confirm a significant increase of transparency in the upper range of the studied energies. The data are confronted to a microscopic transport calculation.