Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 79: Heavy Ion Collisions and QCD phases
HK 79.2: Gruppenbericht
Freitag, 20. März 2009, 11:30–12:00, H-ZO 10
Recent Results from WA98 — •Christoph Baumann — Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Wilhelm-Klemm-Str. 9, 48149 Münster
WA98 has published results on the production of neutral pions and direct photons in Pb+Pb collisions at √sNN=17.4 GeV. We have shown, that the available p+C and p+Pb data measured at √sNN=17.3 GeV can be employed as a replacement for a p+p reference. With the p+A data, the nuclear modification factor of the neutral pion production was computed and a suppression in the most central collisions was observed. We will report on these results and compare them to most recent results from PHENIX in Cu+Cu collisions at √sNN=22.4 GeV. From the direct photon results for Pb+Pb collisions at √sNN = 17.4 GeV published by WA98, the initial temperature of the created state could be constrained to temperatures between 200 and 400 MeV. The spread of these temperatures arises from the uncertainty in the relative amount by which photons from hard scattering processes and thermally produced photons contribute to the photon excess. In this talk, results on the direct photon production in p+Pb and p+C data also measured by WA98 at √sNN = 17.4 GeV are presented and implications for the different production mechanisms in Pb+Pb collisions are discussed.