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Title: The Design of the Sagittal Focusing Monochromator for XAFS Measurement at NSRL

Abstract

The main project of XAFS beamline upgrading at NSRL is to replace the double crystal monochromator with the sagittal-focusing one, of which the diffraction and the focus are compatible. It will increase the photon intensity more than 5 times on the sample with M=1:4.88 geometry and 3 x 0.1 mrad2 acceptance divergence (H x V) without other changes at the primary beamline configuration. This paper introduces concept design of the sagittal-focusing monochromator including optical design, parameters calculation, heat load analysis, mechanical analysis of the flexural hinge-based bender and the mechanism of dynamically energy scanning.

Authors:
; ; ;  [1]
  1. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui (China)
Publication Date:
OSTI Identifier:
21052677
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436217; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ABSORPTION SPECTROSCOPY; BEAM PRODUCTION; CRYSTALS; DESIGN; FINE STRUCTURE; FOCUSING; HEATING LOAD; MONOCHROMATORS; PHOTON BEAMS; PHOTONS; X RADIATION; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Feng Liangjie, Dong Xiaohao, Kang Le, and Xu Chaoyin. The Design of the Sagittal Focusing Monochromator for XAFS Measurement at NSRL. United States: N. p., 2007. Web. doi:10.1063/1.2436217.
Feng Liangjie, Dong Xiaohao, Kang Le, & Xu Chaoyin. The Design of the Sagittal Focusing Monochromator for XAFS Measurement at NSRL. United States. doi:10.1063/1.2436217.
Feng Liangjie, Dong Xiaohao, Kang Le, and Xu Chaoyin. Fri . "The Design of the Sagittal Focusing Monochromator for XAFS Measurement at NSRL". United States. doi:10.1063/1.2436217.
@article{osti_21052677,
title = {The Design of the Sagittal Focusing Monochromator for XAFS Measurement at NSRL},
author = {Feng Liangjie and Dong Xiaohao and Kang Le and Xu Chaoyin},
abstractNote = {The main project of XAFS beamline upgrading at NSRL is to replace the double crystal monochromator with the sagittal-focusing one, of which the diffraction and the focus are compatible. It will increase the photon intensity more than 5 times on the sample with M=1:4.88 geometry and 3 x 0.1 mrad2 acceptance divergence (H x V) without other changes at the primary beamline configuration. This paper introduces concept design of the sagittal-focusing monochromator including optical design, parameters calculation, heat load analysis, mechanical analysis of the flexural hinge-based bender and the mechanism of dynamically energy scanning.},
doi = {10.1063/1.2436217},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • The X-11A beamline at the NSLS has been upgraded to include a dynamic sagittally focusing second crystal in the monochromator, currently operating in the range 5.5--11 keV. The monochromator maintains a constant focus at the sample by adjustment of the bent crystal radius during the XAFS scan. The monochromator accepts 3.3 mrad of horizontal radiation and a spot size of {similar to}1.5 mm{sup 2} is achieved at the sample. The sagittally focusing mechanism in the monochromator is described and the results are presented of intensity profiles, spatial stability, and energy resolution between the energy ranges 6 and 10 keV, wheremore » the system performs most favorably. Intensity gains over unfocused operation are substantial and XAFS studies of dilute fluorescence samples reveal the expected {ital S}/{ital N} improvements, without any introduction of additional noise from the bending process. The mechanism operates with close to 100% efficiency between the energy ranges 6 and 8 keV. Bending errors hinder the performance at higher energies and also preclude effective harmonic rejection, by piezocrystal detuning, over the entire energy range.« less
  • A focusing element that can be added to new and existing x-ray monochromators is described. The bender is used to focus 4 mrad of light into a 300 micron spot (4:1 demagnification). The focus is dynamically adjusted over the energy range 2.1 to 25 keV. This device is a working part of beamline X16C at the NSLS and is routinely used to collect surface diffraction, DAFS, and EXAFS data. Suggestions for its use in other beamlines, including insertion device lines at the APS, will be discussed. {copyright} {ital 1996 American Institute of Physics.}
  • To simplify the complicated mechanism of the traditional double crystal monochromator for synchrotron radiation, a kind of channel cut monochromator with curved reflecting surfaces to fix the exit beam position was successfully developed at NSRL. The performance of this monochromator, which includes the relative efficiency, diffraction bandwidth and deviation of the beam spot, was calculated and measured. The analysis of these results are presented in this paper.
  • Undulators installed in third-generation synchrotron radiation facilities will provide photon beams with high brilliance and large power densities. The optical quality of these beams allows, in principle, the use of simpler optical systems for focusing and monochromatization. In practice the performance of the optical elements is the physical limit to the exploitation of these high brilliance beams. In double-crystal monochromators the bending of the first crystal due to the thermal load and the anticlastic effect on the sagittally bent second one are among the main sources of problems on the overall performances. Here we have considered a double-crystal monochromator withmore » a meridionally bent first crystal followed by a sagittally focusing one. We show that this geometry offers correction either of thermal loads and anticlastic distortions, or minimization of the bandpass or tangential focusing. This can be particularly useful on the high-energy range and for sharp Bragg reflections.« less
  • A new crystal monochromator is designed and tested. The crystal monochromator allows for the use of a large curvature of the sagittal bending and makes it possible to focus synchrotron radiation at a short wavelength and a limited distance from the synchrotron radiation source to the sample.