Electron-Electron Scattering at 500 Mev

The electron-electron differential scattering cross section has been measured with the use of a 500-Mev electron beam from the Stanford Mark III linear electron accelerator. Deviations were sought from the theoretical cross section as calculated in first-order perturbation theory (M{}ller scattering). The experimental results were compared with the M{}ller formula as corrected to the next order in perturbation theory by the work of Tsai.Atomic electrons in a beryllium target foil constituted the target for the electron-electron scattering. The scattered electrons passed through a slit system which defined the angle of scattering and the solid angle. After the particles passed through the slit system, they entered a double-focusing magnetic spectrometer, which analyzed the scattered particles in momentum. The electrons emerging from the spectrometer were detected by a liquid {C} {C}{}erenkov counter. The incident beam was monitored with the use of a Faraday cup and an electronic current integrator.In order to enhance the accuracy of the experiment, the experimental electron-electron scattering was compared to the elastic electron scattering from the target nuclei (Mott scattering).The cross section was measured at approximately 2.6, 3.5, and 4.5 degrees in the laboratory system. These angles correspond to approximately 90, 107, and 120 deg in the center-of-mass system, respectively.The theoretical magnitude of the radiative corrections is -5.5, -4.9, and -4.9% for the scattering angles 2.6, 3.5, and 4.5 deg, respectively. The average experimental deviation from the M{}ller formula found for the above angles was -3.0 (±{}2.3)%, -3.5 (±{}2.9)%, and -5.9 (±{}2.3)%, respectively, where the error cited is total statistical error. In addition to the statistical error there is a maximum estimated ±{}2% possible systematic error.