Influence of reflection asymmetry on coherent emission of relativistic electrons in crystals

The previously proposed method for calculating the yield of diffracted real photons is modified using the Darwin and Prince approach for multiple re-reflections of photons on the reflecting planes of the crystal using the Monte Carlo method. The influence of the asymmetry of the reflecting plane relative to the output surface on the output of diffracted radiation is discussed. The results of measurements of the angular distributions of parametric X-ray radiation (PXR) of relativstic electrons in crystals in which the reflecting plane was not perpendicular to the output surface are analyzed. It is shown that the shape of the angular distributions of the emission of fast electrons in thin crystals can be described with sufficient accuracy in the framework of the kinematic theory of PXR taking into account the contribution of the diffraction of real photons for both symmetric and asymmetric scattering geometry. Information for the conclusion about the ratio of the measured radiation outputs absolute values with the calculated ones is not enough. It is necessary to measure the radiation yields or angular distributions for two identical reflective planes with different asymmetry values for the same experimental conditions.