Planar-Channeling Radiation and Coherent Bremsstrahlung for MeV Electrons

Abstract

The radiation from MeV electrons penetrating a single crystal has been studied. Coherent bremsstrahlung and channeling radiation are discussed theoretically with particular emphasis on the relation between the two phenomena. The close connection becomes clear when the coherent bremsstrahlung is interpreted as radiation from transitions between free states of motion relative to a set of planes, while the planar-channeling radiation is due to transitions between bound states in the planar averaged potential. Detailed calculations of the one-dimensional band structure for such states have been carried out for the case of 4 MeV electrons in silicon, which has also been studied experimentally. In the measured forward-radiation spectra, free-to-free, bound-to-bound, and also free-to-bound transitions have been identified, and the observed energies and intensities are in good agreement with the predictions.