Open AccessEmittance, brilliance, and bandpass issues related to an inclined crystal monochromator
Author(s) -
Albert T. Macrander,
D. R. Haeffner,
P. L. Cowan
Publication year - 1992
Language(s) - English
Resource type - Reports
DOI - 10.2172/90667
Subject(s) - monochromator , diffraction , optics , undulator , reflection (computer programming) , reciprocal lattice , crystal (programming language) , dynamical theory of diffraction , physics , silicon , perfect crystal , beam (structure) , materials science , wavelength , condensed matter physics , optoelectronics , acousto optics , diffraction grating , computer science , vacancy defect , programming language
The inclined double crystal monochromator arrangement is very effective in handling high heat loads and holds considerable promise as a monochromator for undulator beams at third generation synchrotrons. Results for the ideal inclined crystal case have been obtained by dynamical diffraction calculations, and diffraction results for the (111) reflection of silicon are presented for an inclination angle of 85{degrees} and energies of 5 keV and 13.84 keV. The diffraction characteristics resemble closely diffraction from a symmetric (111) plane of silicon. However, the inclined and noninclined cases are not identical. Diffraction in the inclined case is slightly different due to refraction. The full width at half maximum of the Darwin-Prins reflectivity curve is slightly increased ({approximately} 1%), and the angles of the outgoing beam after one reflection are slightly altered. That is, except for a wave incident at the Laue point in reciprocal space, the diffraction is always slightly asymmetric. The effect can be exactly reversed by an identical second crystal in the (+,-) arrangement