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2845 |
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Mechanical Design and Practice of Artificial Channel-cut Crystal Stages for Bonse-Hart USAXS Instrument with 10-Nanoradian-scale Resolution and Stability |
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Design of Precision Machines and Instruments |
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Small-angle X-ray scattering (SAXS) is a nondestructive measurement technique in which the elastic scattering of X-rays from inhomogeneities within a sample is recorded at low scattering angles. The typical range of scattering angles in a pinhole SAXS camera delivers structural information on length scales between 1 nm and 100 nm. To resolve microstructures with larger dimensions, however, the smaller angles available with ultra-small angle X-ray scattering (USAXS) are required. To optimize USAXS experiment performance with high brilliance and low emittance of an Advanced Photon Source (APS) undulator source, an advanced USAXS instrument, using the Bonse-Hart design [1], is developed, installed, and operational at the APS at Argonne National Laboratory [2, 3]. Artificial channel-cut crystal stages [4, 5] are applied for both collimating crystals and analyzer crystals to ensure 10-nanoradian-scale alignment resolution and stability required for their variable multiple-reflection X-ray optics in an angular alignment range of near 1 degree.
In this paper we present mechanical design of the artificial channel-cut crystal stages for the APS USAXS instrument. Finite-element analyses for the laminar weak-link mechanism, as well as X-ray test results for the USAXS crystal X-ray optics, are also presented.
This work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.
References:
1. U. Bonse and M. Hart, Appl. Phys. Lett. 7 (9), 238-240 (1965).
2. J. Ilavsky, D. Shu, P.R. Jemian, and G.G. Long, AIP CP879, 1833-1836 (2007).
3. J. Ilavsky et al., to be published in J. Crystallography, 2009.
4. D. Shu, T.S.Toellner, and E. E. Alp, Nucl. Instrum. and Methods A 467-468, 771-774 (2001).
5. U.S. Patent granted No. 6,607,840, D. Shu, T. S. Toellner, and E. E. Alp, 2003.
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