Photoproduction of Negative Mesons in Deuterium

A 24-in. diffusion cloud chamber filled to 14 atmospheres with tritium-free deuterium gas, operating in a magnetic field of 6 kilogauss, has been placed in the 1040-Mev "hardened" bremsstrahlung beam of the Cornell synchrotron. A total of 310 events of the type $\gamma +d\to p+p+{\pi }^{-}$ have been observed and analyzed. Using the "spectator model," a total cross section has been determined for the reaction $\gamma +n\to p+{\pi }^{-}$ from threshold to 1 Bev, in good agreement with the results obtained from the measurement of the negative-to-positive pion ratio together with the measured cross section for the reaction $\gamma +p\to n+{\pi }^{+}$.