Inclusive photoproduction of charged particles in the forward hemisphere

We report measurements of the invariant cross section in the forward hemisphere for inclusive photoproduction of ${\pi }^{\pm }$, $K^{\pm }$, $p$, and $\overline{p}$ from hydrogen and deuterium with an incident photon energy of 18 GeV. A small amount of data was also taken at incident energies of 9 and 13 GeV. The measurements were made using the SLAC 20-GeV/c spectrometer, and a bremsstrahlung-subtraction technique was used to obtain the cross sections at the specified incident energy. The data are compared with those from lower-energy experiments and interpreted within the context of the Mueller-Regge model and the constituent-interchange model.