Photoproduction of Charged Pi Mesons from Hydrogen and Deuterium

Photoproduction cross sections of charged pi mesons from hydrogen and deuterium have been measured as a function of meson angle at gamma-ray energies of 200, 235, and 265 Mev. The angular range extends from 30° to 180° in the laboratory system. Absolute cross sections have been determined. A least-squares fit of the measured cross sections has been made to the expression $A+Bcos\theta +C{sin}^2\theta$, which assumes only $S$ and $P$ wave scattering. The coefficients so determined are qualitatively consistent with electric and magnetic dipole absorption together with the assumption of a resonant state of angular momentum $\frac{3}{2}$ and of energy close to 300 Mev. Comparison with neutral meson production indicates some direct charged meson production in the $P$ state.