Charge-Exchange Scattering of 34-Mevπ-Mesons in Hydrogen and Deuterium

Abstract

We have measured the total cross section for the charge-exchange scattering of $\ensuremath{\pi}$-mesons in hydrogen and deuterium at 34 Mev. Both single photons and two-photon coincidences were detected. The results are relatively independent of the assumed angular distribution of the $\ensuremath{\pi}$-mesons. A value of 5.0\ifmmode\pm\else\textpm\fi{}1.5 millibarns was obtained for the total charge-exchange cross section of ${\ensuremath{\pi}}^{\ensuremath{-}}$-mesons in hydrogen. The expected null result was obtained for ${\ensuremath{\pi}}^{+}$-mesons in hydrogen. In deuterium, values of about one-third the hydrogen cross section were obtained for both signs of meson. The photons observed from carbon and oxygen do not appear to be mainly from ${\ensuremath{\pi}}^{0}$-decay, and the cross section for ${\ensuremath{\pi}}^{0}$ production in C and O is less than 5 mb for both signs of meson.The two-photon coincidences yield a rough value of 0.8 mb/sterad for the differential charge-exchange cross section for ${\ensuremath{\pi}}^{\ensuremath{-}}$ on hydrogen at 90\ifmmode^\circ\else\textdegree\fi{}. The accuracy is sufficient to rule out the possibility of a very deep minimum at 90\ifmmode^\circ\else\textdegree\fi{}, e.g., a ${cos}^{2}\ensuremath{\theta}$ angular distribution.