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HK: Hadronen und Kerne
HK 24: Heavy Ion Reactions III, Ultrarelativistic Energies
HK 24.3: Gruppenbericht
Dienstag, 17. März 1998, 14:30–15:00, P
Coulomb Mean Field Effects in Relativistic Heavy-Ion Reactions on One- and Two-Particle Spectra* — •H.W. Barz1, J.P. Bondorf2, J.J. Gaardhoje2, and H. Heiselberg3 — 1Institut f"ur Kern und Hadronenphysik, Forschungszentrum Rossendorf, Pf 510119, D-01314 Dresden — 2Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen, Denmark — 3NORDITA, Blegdamsvej 17, 2100 Copenhagen, Denmark
In systems with a large charge number up to ∼160 the momentum distribution of charged particles is remarkably affected. Therefore, the π−/π+ ratios measured in relativistic heavy-ion collisions are enhanced several times at small momenta. These ratios decrease with increasing bombarding energy. A dynamical model is developed which is based on the calculation of pion trajectories in the time dependent electromagnetic field. It is applied to reactions with bombarding energies between 1 A·GeV and 158 A·GeV measured recently at SIS, AGS and SPS accelerators. The model permits to relate the pion asymmetry to the freeze-out parameters as temperature, transverse flow, freeze-out time and charge distribution. The strong central Coulomb field also influences the two-particle correlations of charged particles. with mean momenta around 200 MeV/c. Source radii in sideward and outward direction extracted from interferometry measurements with mesons of momenta around 200 MeV/c deviate clearly from their true values if Coulomb effects are diregarded. The effects are opposite for negatively and positively charged mesons. Comparison with recent data is made.
* partially supported by BMBF