Simultaneity in the Compton Effect

The Bothe-Geiger experiment has been repeated under improved conditions of time resolution, obtained by using stillbene scintillation counters. The recoil electron and scattered photon are emitted together within a time interval of less than 1.5×${10}^{-8\mathrm{}}$ second. The electron and photon are also projected without a delay larger than 1.5×${10}^{-8\mathrm{}}$ second after arrival of a quantum. The familiar concepts used in discussions of the Compton effect are shown to be valid.