Two years ago, at the 12th Winter Workshop on Nuclear Dynamics held here in Snowbird, the authors presented WA80 limits on direct photon production in 200-GeV 32S + Au collisions. It was found that the results were consistent (within 1[sigma]) with the absence of an excess of photons over those that can be accounted for by the two-photon decay branches of [pi]° and [eta] mesons and by the small photon contributions from other radiative decays. They are in the process of finalizing the direct-photon production results from collisions of lead nuclei at 158 GeV/nucleon. The author briefly discusses the status of the analysis and gives some preliminary results at the end of this talk. However, most of this presentation is concerned with a very different aspect of the photon measurements: distributions of neutral pions. In contrast to direct photons which probe initial collision conditions, hadrons, such as neutral pions, interact strongly and decouple late in the reaction evolution and, thus, provide information concerning the system at freeze out. Transverse momentum spectra at low and intermediate p{sub T} relate to thermodynamic and hydrodynamic descriptions of the hot, dense systems. In addition, the high-p{sub T} region reflects the hard-scattering regime and may help one understand initial-state particle production by forming a bridge to proton-proton and proton-nucleus results. It follows that it is essential that the [pi]° measurements cover a large p{sub T} range.

Two years ago at the 10th Winter Workshop on Nuclear Dynamics, we reported preliminary results from our measurements of photons in reactions of 200·A GeV 32S ions with Au nuclei. The results had been presented earlier at Quark Matter '93. For central collisions we reported a small, but statistically significant, excess of photons over those that can be accounted for by the two-photon decay branches of neutral pions and eta mesons and by the small photon contributions from other radiative decays. This paper is, in a sense, a sequel to the 1994 presentation. Here we present the final WA80 single 'direct' photon results, and we discuss their implications for various theoretical calculations. 13 refs., 2 figs., 1 tab.