Darmstadt 2008 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 6: Physik mit schweren Ionen
HK 6.7: Talk
Monday, March 10, 2008, 15:45–16:00, 2E
π0 production in Pb on Au collisions at 158 AGeV measured at the CERN SPS — •Rachik Soualah for the CERES collaboration — Physikalisches Institut, Universität Heidelberg, Germany
The study of direct photons is a particularly useful probe to search for an evidence of quark-gluon plasma formation
in ultrarelativistic heavy-ion collisions. Direct photons are very difficult to measure experimentally
due to the large background from π0 and η meson decays. A significant yield of direct photon has been reported by
WA98 experiment at SPS where the main systematic error comes from the yield of η mesons, measured only poorly at SPS
energies. In addition, the main source of systematic errors in the measurement of the dilepton pairs in the low mass range,
main physics topic of the CERES experiment, comes from the η/π0 ratio.
CERES can detect the photons that convert shortly before the TPC by the reconstruction of e+e− pair conversions from
charged tracks measured with the CERES TPC.
In this contribution, the techniques employed to measure photons and the preliminary transverse momentum spectrum of neutral pions will be presented.