Optical Emission from Irradiated Foils. II

Abstract

The spectra from silver foils irradiated by electron beams from an accelerator consist of weak maxima at 3500 Å and broad continua at longer wavelengths. The intensity of the maxima do not exhibit as strong a dependence on foil thickness as predicted by Ferrell and reported by Steinmann. The intensities of both maxima and the continua were found to be directly proportional to beam energy over the range from 40 kev to 115 kev in agreement with the experiments of Goldsmith and Jelley, and of Boersch et al., and the theory of Ginsburg and Frank for transition radiation. The intensity of similar continua found for Al, Au, and Mg also increased linearly with beam energy. Light from Ag and Al foils was found to be polarized in the plane containing the foil normal and the photon direction as predicted theoretically. The intensity of the light from silver was found to be small near the foil normal and at angles approaching 90°, and to achieve a maximum at an intermediate angle in agreement with the theories of Ferrell, and of Ritchie and Eldridge. The absolute light yield from foils of Al and Ag revealed substantial agreement with the predictions of Ritchie and Eldridge from the transition theory of Frank and Ginsburg.