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Title: On the influence of monochromator thermal deformations on X-ray focusing

A cooled double crystal monochromator system is used on many high heat load X-ray synchrotron radiation beamlines in order to select, by diffraction, a narrow spectrum of the beam. Thermal deformation of the first crystal monochromator – and the potential loss of beam brightness – is often a concern. However, if downstream beam focusing is planned, the lensing effect of the monochromator must be considered even if thermal deformations are small. In this paper we report on recent experiments at an Advanced Photon Source (APS) beamline that focuses the X-ray beam using compound refractive lenses downstream of an X-ray monochromator system. Increasing the X-ray beam power by increasing the storage ring current from 100 mA to 130 mA resulted in an effective doubling of the focal distance. We show quantitatively that this is due to a lensing effect of the distorted monochromator that results in the creation of a virtual source downstream of the actual source. Lastly, an analysis of the defocusing and options to mitigate this effect are explored.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [3]
  1. Univ. of Illinois, Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Peter the Great St. Petersburg Polytechnic Univ., St. Petersburg (Russia)
  2. Illinois Inst. of Technology, Chicago, IL (United States); Univ. of Illinois, Chicago, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
OSTI Identifier:
1267179
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 820; Journal Issue: C; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; cooling; focusing; monochromator; synchrotron x-ray radiation; thermal Deformations