Limits on the Production of Direct Photons in 200<i>A</i>GeV<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>S</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>32</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow><mml:mo>+</mml:mo><mml:mi>A</mml:mi><mml:mi>u</mml:mi></mml:math>Collisions

A search for the production of direct photons in $\mathrm{S}+\mathrm{Au}$ collisions at $200A\mathrm{GeV}$ has been carried out in the CERN-WA80 experiment. For central collisions the measured photon excess at each ${p}_{T}$, averaged over the range $0.5\ensuremath{\le}{p}_{T}\ensuremath{\le}2.5\mathrm{GeV}/c$, corresponded to 5.0% of the total inclusive photon yield with a statistical error of ${\ensuremath{\sigma}}_{\mathrm{stat}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.8%$ and a systematic error of ${\ensuremath{\sigma}}_{\mathrm{syst}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5.8%$. Upper limits on the invariant yield for direct photon production at the 90% C.L. are presented. Possible implications for the dynamics of high-energy heavy-ion collisions are discussed.