Spectral and polarization characteristics of X-ray hybrid radiation.

• Interference of transition and Cherenkov radiation fields causes hybrid radiation. • Interference sets the range of the angular distribution with monochromatic X-rays. • Monochromaticity of Cherenkov X-rays is limited by transition radiation influence. • We predict a spectral asymmetry of hybrid radiation in the soft X-ray range. • Considered radiation geometry allows controlling X-rays spectrum and polarization. Vavilov-Cherenkov emission and transition radiation are the well-known phenomena and find a broad application for different scientific communities. In the case of simultaneous generation of both types of radiation, there is a possibility of interference between radiation fields. Thus, the emitted radiation could possess both transition radiation and Vavilov-Cherenkov radiation properties, that is why it should be considered as hybrid radiation. In this paper, we present the results of the theoretical investigation of X-ray hybrid radiation. Using the polarization current approach and the atomic scattering factor formalism to account anomalous dispersion of the complex permittivity we study spectral-angular distributions and polarization states of X-ray hybrid radiation when a charge obliquely falls on a foil. The theoretical results greatly contribute to understanding of X-ray Vavilov-Cherenkov radiation as well as the development of the X-ray narrow band radiation sources based on Vavilov-Cherenkov effect. [ABSTRACT FROM AUTHOR]