Prompt Photon Production in 300 GeV/c π -p, π +p and pp Collisions

From the measurement of prompt photon production at large transverse momentum one can obtain fairly clean information about constituent scattering dynamics, since the photon is a direct participant of the constituent scattering process. With the use of pion beams, the experiment aimed at the observation of the QCD-annihilation process. Rather precise measurements of direct photon cross sections in this experiment provide a good test of QCD, in particular since next to leading order terms are included in the QCD predictions.