Production of Mesons by Photons on Nuclei

Abstract

The total cross section, energy spectrum, and angular distribution of mesons produced by photons incident on a target nucleus have been expressed in terms of the nucleon momentum distribution within the nucleus. The theory used here is valid for photon energies greater than approximately 1.2 times threshold, and for all but the lightest nuclei. These results have been applied to carbon employing Goldberger and Chew's momentum distribution for the protons in carbon. Excellent agreement is obtained for the meson energy spectrum at 90° and the decrease in efficiency of meson production compared to free protons as targets. The change in efficiency with photon energy, and the meson spectrum at various angles can be used to determine the internal nucleon momentum distribution. Positive mesons yield the proton distribution, negative mesons the neutron distribution.