A PROPOSED MULTI-BEAM X-RAY MONOCHROMATOR FOR SYNCHROTRON RADIATION : THEORETICAL CONSIDERATIONS

Abstract
An X-ray monochromator utilizing multi-beam simultaneous reflection is proposed for synchrotron radiation. The monochroator is an asymmetrically cut perfect single crystal, which is set for a multiple diffraction. The spatial width, the angular divergence and the wavelength dependence of the multiply diffracted beam in relaton to the incident beam parameters are considered theoretically, based on a two-beam approximation of the dynamical theory of X-ray multiple diffraction. The transformation matrices between the parameters of the incident and the diffracted beams are derived in the position-angle-wavelength scheme. It is found that a tunable angular acceptance for the incident beam and a reduction in the diffraction beam-divergence can be achieved by selecting a proper multiple diffraction.