Ratio of the parametric X-radiation yields in the Bragg direction and along the relativistic electron velocity in the Bragg geometry

Parametric X-radiation (PXR) and parametric radiation at a small angle to the relativistic electron velocity (FPXR) that arises from electron motion through a monocrystalline plate in Bragg scattering geometry are analyzed on the basis of the dynamic diffraction theory. The expressions for spectral-angular densities of these radiations have been derived in the general case of asymmetric field reflections from a target surface. They make it possible to reveal the noticeable dependence of the ratio of the PXR and FPXR yields on the angle between reflecting atomic planes and the surface of a monocrystalline plate, i.e., reflection asymmetry.