Influence of real photon diffraction on parametric X-ray radiation angular distribution in thin perfect crystals

Using the previously proposed method of calculating diffracted photon yields in thin perfect crystals, analyzed a relative contribution of parametric X-ray radiation and diffracted photons in thin crystals. It is shown that for average energy of electrons and the center of the PXR spot diffracted real photon contribution is comparable to the yield of parametric X-ray radiation and determines the shape of the angular distribution of the total emission in this range of observation angles. The possibility of estimating electron beams parameters based on the results of PXR angular distribution measurements is discussed. It is shown that for energy of electrons by far larger than 1 GeV yield of diffracted transition radiation in narrow angular cone becomes predominating and determines the shape of the angular distribution of total emission in the center of radiation spot.