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Title: Characterization of a bent Laue double-crystal beam-expanding monochromator

A bent Laue double-crystal monochromator system has been designed for vertically expanding the X-ray beam at the Canadian Light Source's BioMedical Imaging and Therapy beamlines. Expansion by a factor of 12 has been achieved without deteriorating the transverse coherence of the beam, allowing phase-based imaging techniques to be performed with high flux and a large field of view. However, preliminary studies revealed a lack of uniformity in the beam, presumed to be caused by imperfect bending of the silicon crystal wafers used in the system. Results from finite-element analysis of the system predicted that the second crystal would be most severely affected and has been shown experimentally. It has been determined that the majority of the distortion occurs in the second crystal and is likely caused by an imperfection in the surface of the bending frame. Here, measurements were then taken to characterize the bending of the crystal using both mechanical and diffraction techniques. In particular, two techniques commonly used to map dislocations in crystal structures have been adapted to map local curvature of the bent crystals. One of these, a variation of Berg–Berrett topography, has been used to quantify the diffraction effects caused by the distortion of the crystalmore » wafer. This technique produces a global mapping of the deviation of the diffraction angle relative to a perfect cylinder. Finally, this information is critical for improving bending and measuring tolerances of imperfections by correlating this mapping to areas of missing intensity in the beam.« less
Authors:
 [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [2] ;  [2] ;  [3]
  1. Univ. of Saskatchewan, Saskatoon, SK (Canada). Physics and Engineering Physics
  2. Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division
  3. Canadian Light Sources, Inc., Saskatoon, SK (Canada)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Synchrotron Radiation (Online)
Additional Journal Information:
Journal Name: Journal of Synchrotron Radiation (Online); Journal Volume: 24; Journal Issue: 6; Journal ID: ISSN 1600-5775
Publisher:
International Union of Crystallography
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC); Natural Sciences and Engineering Research Council of Canada (NSERC); Canadian Institutes of Health Research (CIHR); Canada Foundation for Innovation; Government of Saskatchewan; Western Economic Diversification Canada
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Lang topography; Berg-Barrett topography; beam expander; double bent Laue monochromator; finite element analysis; finite-element analysis
OSTI Identifier:
1425211