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Performance of multi-crystal Bragg X-ray spectrometers under the influence of angular misalignments

DOI: 10.1016/j.nima.2008.02.018 DOI Help

Authors: John Sutter (Diamond Light Source) , Graham Duller (Diamond Light Source) , Ulrich Wagner (Diamond Light Source) , Shusaku Hayama (Diamond Light Source) , Sofia Diaz-moreno (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nuclear Instruments And Methods In Physics Research Section A , VOL 589 , PAGES 118 - 131

State: Published (Approved)
Published: March 2008

Abstract: X-ray beams have long been analyzed by series of Bragg reflections from crystals arranged in various configurations. The dependence of reflectivity and selected wavelength on the beam's incidence angle makes proper crystal alignment crucial, particularly as the number of crystals increases. A list of possible misalignments and a method for calculating their effects on the selected wavelengths, output beam positions, and throughputs are presented here. The following goes beyond the DuMond diagram to include rolls and rotation axis misalignments. These are described for a single crystal, and a ray-tracing method is derived for multiple crystals assuming that the misalignment angles are small. The angles are classified by their lowest-order term. Reflectivities for each ray are calculated by the equations of plane-wave dynamical diffraction theory. Then, as a practical application, sample calculations are discussed for the (+--+)(+--+) four-crystal monochromator being designed for beamline I20 at the Diamond Light Source.

Journal Keywords: Alignment; Beam Position; Beams; Bragg Reflection; Diagrams; Diamonds; Diffraction; Incidence Angle; Light Sources; Monochromators; Monocrystals; Performance; Reflectivity; Wave Propagation; Wavelengths; X Radiation; X-Ray Spectrometers

Subject Areas: Physics, Technique Development

Technical Areas: Optics

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