An Apparent Failure of the Photon Theory of Scattering

A test has been made of the photon theory of the scattering of high frequency radiation. The pairs of scattered photons and recoil electrons predicted by this theory have been looked for by means of specially designed Geiger-Müller counters. Coincident discharges in the electron and photon counters were recorded by means of a vacuum tube amplifying and adding circuit. The scatterers used were air, aluminum, beryllium, filter paper and paraffin. The radiation was the gamma-rays from radium C. Experiments were performed with the counters set at various angles, some where the photon theory predicts coincidences, and others where coincidences should not be expected. The experiments uniformly gave fewer coincidences in the correct positions than were expected, and those observed could in every case be accounted for as chance coincidences due to the finite resolving time of the apparatus. It has not been found possible to bring the results of these experiments into accord with the photon theory of scattering. The wave-mechanical theory of the scattering process has not yet been extended to include the gamma-ray region so that it is impossible to compare this theory with the present experiments. Unless it is shown that the two theories disagree in the gamma-ray region it does not seem possible to reconcile the present experiment with the Bothe-Geiger and Compton-Simon experiments.