1960 photoprod uction of charged pions near threshold

We have measured the differential cross section for the photoproduction of positively-charged 1r mesons on hydrogen at photon energies 153 -175 Mev. We also give the total cross section for the photoproduction of negative 1r mesons on deuterium. A comparison is made between the experimental and theoretical values for the squares of the matrix elements I Kp 12 and I Kn 12 for the photoproduction of 1r+ and 1rmesons on free nucleons. The quantity I Kn 12 is compared with the Panofsky ratio and with the meson -nucleon interaction S -phase shifts. The value of the ratio a/a+ has been obtained in the photon-energy range from 153 to 175 Mev.