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Search for direct photons from S-Au collisions at 200 GeV/nucleon |
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| Authors: | R Baur A Breskin R Chechik A Drees C Jacob U Faschingbauer P Fischer Z Fraenkel E Gatti P Gl?ssel Th G??nzel C P de los Heros F Hess D Irmscher B Lenkeit L H Olsen Y Panebrattsev A Pfeiffer I Ravinovich P Rehak A Sch?n J Schukraft M Sampietro A Shor H J Specht V Steiner S Tapprogge G Tel-Zur I Tserruya Th Ullrich J P Wurm |
| Institution: | 1. Physikalisches Institut der Universit?t Heidelberg, 69120, Heidelberg, Germany 2. Weizmann Institute, 76100, Rehovot, Israel 3. Max-Planck-Institut f??r Kernphysik, 69117, Heidelberg, Germany 4. Politecnico di Milano, 20133, Milano, Italy 5. Brookhaven National Laboratory, 11973, Upton, NY, USA 6. CERN, 1211, Geneva 23, Switzerland |
| Abstract: | The CERES experiment has measured inclusive photon production in S-Au collisions of 200 GeV/nucleon at the CERN SPS. No evidence for direct emission of photons was found. For the kinematic region 2.1<y<2.65 and 0.4 GeV/c<p??<2.0 GeV/c the yield andp??-dependence of the observed photons are well reproduced by hadron decays. Furthermore, their production rate is found to be proportional to the charged particle density. The systematic errors comparing the measured and expected photon yield result in an upper limit of 14% for the emission of direct photons in central S-Au collisions. For a photon source with a yield depending quadratically on the charged particle density the limit can be reduced to 7%. |
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