The Absorption of High Energy Electrons, Part I

The recoil electrons produced by the 6 Mev gamma-radiation from fluorine bombarded with protons were allowed to pass through 5 mm carbon and 0.5 mm lead absorbers placed across the center of a cloud chamber. The curvatures of the incident and emergent tracks in the magnetic field were measured, the difference giving the loss in passing through the absorber. The losses in carbon are in good agreement with the theoretical losses due to electron collisions alone, and this is satisfactory, since practically no radiative losses are expected in a substance of such low atomic number. In the case of lead, the data show clearly that radiative losses play a large part, and increase with increasing energy of incident particle. The losses in lead are slightly greater than those predicted by theory.