Study of inclusive γ and π0 production in 12.4-GeV/c pp interactions

From an exposure of the Argonne National Laboratory 12-foot bubble chamber to a beam of 12.4-GeV/c protons we have obtained a 3649-event sample of the reaction pp→γ+anything, where we observe photon conversions into e+e- pairs in the liquid hydrogen. We find that the invariant cross section for this reaction does not separate in its x and P dependence at our energy. By setting upper bounds on the cross sections for inclusive η and 0 production, we show that π0 decay is the dominant source of photons and therefore measure the cross section for inclusive π0 production to be σ(π0)=(31.5±2.6) mb. Comparison with the inclusive π+ and π- cross sections at 12.0 GeV/c shows that the relation 2σ(π0)=σ(π+)+σ(π-) is well satisfied. We confirm earlier indications that the average number of π0's per inelastic pp interaction is approximately independent of the number of associated charged particles produced.