PARAMETRIC X-RAY RADIATION, TRANSITION RADIATION AND BREMSSTRAHLUNG IN X-RAY REGION. A COMPARATIVE ANALYSIS

摘要

The diffraction of the real photons (BS or TR) is more intense than diffraction of the virtual photons (PXR) for thick mosaic crystals. The suppression of the bremsstrahlung and axial channeling radiation in the X-ray region (ω ≤ γω_p) for initial electron energy less than 1 GeV observed in our experiment is connected with the effect of the medium polarization. Due to this effect the transition radiation should be considered as the most intense source of photons in the range ω < γω_p. In opposite case (ω >γω_p) the most intense source is the axial channeling radiation. The usage of a crystal-monochromator allows to obtain the photon beam with ～ 1% bandwidth with some intensity loss. The reflection efficiency of a pyrolitic graphite achieves ～ 20% in the ～ 10 keV region. The periodic foil stack target could provide the significant growth of the initial beam intensity. But such factors as electron multiple scattering, target imperfectness, finite beam collimation angle entail the deterioration of the resonant condition. As a consequent the typical value of the monochromaticity of RTR beam is around 10% that may demand the following monochromatization. In this case the foam target from a light substance with pore sizes compared with formation length may provide the similar intensity of the photon beam as a RTR target.