THE ANGULAR AND SPECTRAL DISTRIBUTIONS OF LIGHT EMITTED FROM ELECTRON-BOMBARDED SILVER FOILS

摘要

The spectral distribution of photons emitted by Ag foils 660 A and 1980 A in thickness bombarded by 40-keV electrons has been determined experimentally in the wavelength region from 2500 A to 5600 A. The spectra were determined for photons emitted at 0 to 150 from the foil normal using an angular distribution chamber which permitted the spectrometer to be rotated around the foil in a continuous fashion without breaking the vacuum. A Glan prism analyzer was used to separate the light into a component polarized parallel to the plane of the electron and photon and another component perpendicular to it. Transition radiation/ as was shown by Frank and Ginzburg, is polarized in the parallel plane, whereas bremsstrahlung has both a parallel and perpendicular component. The photon in the perpendicular plane was found to be about 10% of that in the parallel plane. The spectrum in the parallel plane showed a sharp peak at 3300 A, this value being an average over photon directions from 10 to 50 from the foil normal. This agrees with the theoretical predictions and is within the limits of error of previous determinations at 300.