We have measured the bremsstrahlung yield at 6.2° in the reaction $e^{-}+\mathrm{C}\to e^{-}+\mathrm{C}+\gamma$ using incident-electron energies up to 9.5 GeV. The data confirm the predictions of quantum electrodynamics for timelike electron four-momenta up to 1 GeV.

• Received 22 January 1969

DOI:https://doi.org/10.1103/PhysRevLett.22.421