High precision measurement of Compton scattering in the 5 GeV region

The cross section of atomic electron Compton scattering \gamma + e \rightarrow \gamma^\prime + e^\prime was measured in the 4.40--5.475 GeV photon beam energy region by the {\em PrimEx} collaboration at Jefferson Lab with an accuracy of 2\% and less. The results are consistent with theoretical predictions that include next-to-leading order radiative corrections. The measurements provide the first high precision test of this elementary QED...