Positron-electron annihilation in flight between 2 and 10 GeV

The total cross-section for positron-electron annihilation in flight was measured at incident positron laboratory energies of 1.94, 5.80, 7.71 and 9.64 GeV. The measured values are (0.520±0.013) mb, (0.198±0.006) mb, (0.154±0.005) mb, and (0.128±0.007) mb, respectively. The positron beam was obtained by conversion of photons emitted from an internal target of the CERN Proton Synchrotron. The measured cross-sections agree with the theoretical values including radiative corrections.