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HK: Fachverband Physik der Hadronen und Kerne

HK 1: Eröffnung und Hauptvorträge

HK 1.2: Hauptvortrag

Montag, 10. März 2008, 09:30–10:00, 1B/C

Dielectron production in elementary and heavy ion collisions with HADES — •Piotr Salabura for the HADES collaboration — Jagiellonian University, Krakow, Poland — GSI, Darmstadt, Germany

HADES is a second generation experiment operated at GSI Darmstadt with the main goal to study dielectron production in proton, pion and heavy ion induced reactions. The first part of the HADES mission is to reinvestigate the puzzling pair excess measured by the DLS collaboration in C+C and Ca+Ca collisions at 1 AGeV. For this purpose dedicated measurements with C+C system at 1 and 2 AGeV were performed [1]. Pair excess above a cocktail of free hadronic decays has been extracted and compared to the one measured by DLS. Furthermore, the excess will be confronted with predictions of various model calculations. These calculations suffer from incomplete knowledge of some elementary processes, most importantly Dalitz decays of baryonic resonances (mainly Δ(1232)) and NN bremsstrahlung. In order to shed more light on these processes p-p and d-p collisions have been investigated. Preliminary results from these experiments will be presented and discussed. The second important part of the HADES physics programme is high resolution spectroscopy of the vector mesons(ρ/ω) region. Such investigations have been started with Ar+KCl collisions at 1.75 GeV and p-p at 3.5 GeV. High statistics data sample (≈ 150000 pairs) collected for Ar+KCl has already been analyzed. First results will be presented and compared to model predictions.

[1] G. Agakichiev et al. (HADES Collaboration), Phys. Rev. Lett. 98 (2007)052302