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Bent Bragg–Laue monochromator for high‐energy X‐rays
Author(s) -
Shi Xianbo,
Xu Wenqian,
Yakovenko Andrey,
Halder Gregory,
Liu Zunping,
Kurtz Charles,
Ribaud Lynn,
Beyer Kevin,
Chapman Karena,
Chupas Peter
Publication year - 2017
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576717009098
Subject(s) - bent molecular geometry , monochromator , wiggler , optics , crystal (programming language) , bragg's law , physics , curvature , bending , geometry , materials science , diffraction , cathode ray , wavelength , mathematics , quantum mechanics , computer science , composite material , thermodynamics , programming language , electron
A bent Bragg–Laue monochromator (BLM) is proposed for high‐energy X‐ray (∼25–60 keV) beamlines. The BLM has the unique feature of bi‐directional focusing. A sagittally bent Laue crystal can focus the large horizontal fan of a bending magnet or wiggler source. A meridionally bent Bragg crystal focuses the beam vertically and corrects for the anticlastic bending effects of the Laue crystal. This monochromator geometry relies on the crystal orientations being optimized. It is shown that the focusing condition and Rowland condition can be simultaneously satisfied at a given energy. Detailed ray tracings indicate that a BLM can provide similar energy resolution and higher flux density compared to a sagittally bent double‐Laue monochromator configuration. A prototype BLM with a symmetric Bragg crystal and an asymmetric Laue crystal was tested. Matching of the bend radii of the two crystals in the meridional direction was demonstrated. In general, the horizontal acceptance of the sagittally bent Laue crystal is limited by the large curvature. This horizontal BLM acceptance could be increased by translating the Laue crystal along its sagittal bending axis.