Recoil Correction to Bremsstrahlung Cross Section

A correction to the Bethe-Heitler differential cross section for bremsstrahlung (or pair production) due to the recoil of the source of the Coulomb field (proton) is derived. Terms of order $\frac{v}{c}$, where $v$ is the recoil velocity of the scattering center, are studied. They are shown not to contribute in the analysis of electron-proton scattering given by Schiff in the preceding paper.