Pion-Electron Scattering Cross Section at 1.12 Bev/c

Abstract

We have measured the absolute differential cross section $\frac{d\ensuremath{\sigma}}{\mathrm{dK}}$ for production of delta-ray electrons by 1.12-Bev/c negative pions incident on a 10-in. liquid hydrogen bubble chamber, for values of the $\ensuremath{\delta}$-ray kinetic energy $K$ between 32 Mev and the kinematical upper limit of 62 Mev. The results are in agreement with the theoretical prediction of Bhabha. We find an integrated cross section $\ensuremath{\sigma}(K>32 \mathrm{Mev})=1.37\ifmmode\pm\else\textpm\fi{}0.17 \mathrm{mb}.$ This exceeds the theoretical prediction of 1.17 mb by a factor 1.17\ifmmode\pm\else\textpm\fi{}0.15.The monoenergetic electron contamination of the pion beam has been determined by counting electron-induced $\ensuremath{\delta}$ rays. The monoenergetic and non-monoenergetic contributions to the muon contamination have both been determined by combining a determination of the number of muon-induced $\ensuremath{\delta}$ rays with a measurement of the curvature distribution of beam tracks. The method is described in detail.