On the Theory of Diffraction of Limited Synchrotron Radiation Beams in Single Crystal in the Laue Case

The features of the Bragg diffraction of coherent synchrotron radiation from the atomic lattice of a single crystal in the Laue geometry have been studied theoretically, provided that the radiation beam is limited by a relatively large slit placed in front of the crystal. The method of numerical simulation is used, and dependences of the intensity distribution are obtained for different crystal thicknesses. It is shown that the slit edges introduce inhomogeneous intensity distortions inside the Borrmann fan with an angle of 2θ_B, where θ_B is the Bragg angle. In the area where the triangles intersect the intensity distribution is similar to that for the diffraction from a slit in air at a certain (large) distance. An equation for the correspondence between the distance and crystal thickness is derived, which describes well the numerical calculation results.