SEARCH FOR DIRECT PHOTONS FROM S-AU COLLISIONS AT 200 GEV NUCLEON/

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(perpendicular to) < 2.0 GeV/c the yield and p(perpe ndicular to)-dependence of the observed photons are well reproduced by hadron decays. Furthermore, their production rate is found to be prop ortional to the charged particle density. The systematic errors compar ing the measured and expected photon yield result in an upper limit of 14% for the emission of direct photons in central S-Au collisions. Fo r a photon source with a yield depending quadratically on the charged particle density the limit can be reduced to 7%.