POSITRON-PROTON ELASTIC SCATTERING AT 800 AND 1200 MEV

The cross section for the elastic scattering of positrons from protons has been compared with the corresponding electron cross section using secondary beams derived from the photon beam of the Cornell 2-GeV synchrotron. The paths of the scattered leptons (positrons or electrons) and recoil protons were recorded in spark chambers and were used to determine the incident lepton energy of each event. Elastic scatterings were identified by requiring coplanarity and a fit to the scattering kinematics. The detection system was sensitive to scattering angles between 25°and 75°. The ratio of the positron cross section to the corresponding electron cross section was 0.992±0.017 at 800 MeV and 0.987±0.019 at 1200 MeV. No significant variation of the ratio with angle of scattering was found. © 1968 The American Physical Society.