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HK: Physik der Hadronen und Kerne
HK 18: Physik mit schweren Ionen
HK 18.1: Gruppenbericht
Montag, 7. März 2005, 14:00–14:30, TU MA041
Direct Photon Production Measured with the PHENIX Experiment — •Christian Klein-Bösing and Baldo Sahlmüller — Institut für Kernphysik, Wilhelm-Klemm-Str. 9, 48149 Münster
Direct photons with a large transverse momentum pT are in heavy ion collisions predominantly produced by parton scattering in the early phase of the reaction, similar to the direct photon production in p+p collisions. An additional source in heavy ion collisions is the thermal production in the possible quark-gluon plasma phase and in the subsequent hadron-gas phase, as well as the interaction of hard scattered partons with the medium.
The search for direct photons is in general a difficult task because of the large photon background from the decay of π0s and other mesons. But while the production of π0s with high transverse momentum in central Au+Au collisions is suppressed due to final state interactions of the hard-scattered partons, direct photons should be unaffected by the surrounding medium. The comparison of the photon and neutral pion production at large pT in heavy ion collisions thus provides a direct verification of the jet quenching scenario, while the direct photon production in the intermediate pT region (pT = 1−3 GeV/c) is most sensitive to thermal sources, such as the QGP.
This work is supported by BMBF.