Bochum 1998 – scientific programme
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HK: Hadronen und Kerne
HK 34: Heavy Ion Reactions IV, Relativistic Energies
HK 34.2: Group Report
Tuesday, March 17, 1998, 17:30–18:00, P
Phase Space Distributions of Nucleons, Light Fragments and Produced Particles in Relativistic Heavy-Ion Collisions — •Y. Leifels — GSI Darmstadt, Uni Heidelberg, FZ Rossendorf, IPNE Bucharest, KFKI Budapest, LPC Clermont-Ferrand, ITEP/KI Moscow, IReS Strasbourg, Korea University Seoul, RBI Zagreb
The properties of hot (T ≤ 100 MeV) and dense (ρ ≤ 3 ρ0) hadronic matter are currently investigated at the SIS of GSI by colliding relativistic heavy ions in a variety of symmetric systems ranging from Ni+Ni to Au+Au at energies between 0.1 and 2.0 GeV. With the 4π-Detector, FOPI, light charged mesons π+, π−, K+, and K− as well as K∘ and Λ are identified together with the light fragments (p, d, t, 3He, α). At all incident energies a significant azimuthally symmetric transverse flow component is observed in central collisions. In light systems (Ni+Ni) phase space distributions of nucleons and fragments are more elongated than in heavy ones (Au+Au). This may indicate less amount of stopping in small systems. Colliding equal mass nuclei with different N/Z ratios allows to follow more directly how protons and neutrons propagate and mix. By observing the local evolution of the isospin measured by the t/3He ratio in phase space it is possible to study the equilibration process in detail and model independently. Results on an experiment with 96Zr/Ru isotopes investigating thermalization and stopping at two different incident energies are presented. With the precise knowledge of the baryon dynamics one has a reference for the phase space distributions of strange particles. Theoretical models predict a strong sensitivity of phase space distributions as well as sideflow patterns of kaons to the in-medium kaon potential. For the first time finite sideflow was observed for K+ and the implications will be discussed.