Measurement of Moller Scattering at 2.5 MeV

Møller scattering is one of the most fundamental processes in QED. Its knowledge at high precision is necessary for a variety of modern nuclear and particle physics experiments. However, most treatments have neglected the electron mass, which is an approximation that breaks down at relevant low energies. In this work, existing soft-photon radiative corrections were combined with new hard-photon bremsstrahlung calculations to take into account the effect of photon emission at any photon energy. The electron mass was included at all steps. The radiative corrections were compiled into a Monte-Carlo event generator. To test the results, an experiment was designed, constructed, installed, and executed at the MIT High Voltage Research Laboratory. Measurements are reported, comparing the simulated radiative Møller spectra to data at 2.5 MeV. Good agreement between the measurements and the new calculation is observed in the momentum spectrum at three angles.