Further Results on the Production of Neutral Mesons by Photons

Abstract

Further measurements have been made on the photoproduction of neutral mesons using the gamma-gamma coincidence technique. New data have been obtained on the gamma-gamma correlation curves in beryllium. The angular distribution of the photomesons in Be has been determined and found to be strongly peaked forward. The dependence on the atomic number $A$ of production has been found to obey an ${A}^{\frac{2}{3}}$ law. Some data obtained for production in hydrogen show that the ${\ensuremath{\pi}}^{0}$ and ${\ensuremath{\pi}}^{+}$ production cross sections are comparable and that the ${\ensuremath{\pi}}^{0}$ excitation curve starts more slowly from threshold than does the ${\ensuremath{\pi}}^{+}$ photo-excitation curve.