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Proceedings Paper

Simulation and optimization of a sub-micron beam for macromolecular crystallography using SHADOW and XOP at GM/CA CAT at the APS
Author(s): Zunping Liu; Shenglan Xu; Derek W. Yoder; Robert F. Fischetti
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Paper Abstract

The small, high intensity and low convergence beams available on beamlines at 3rd generation synchrotron sources have been a boon to macromolecular crystallography. It is now becoming routine to solve structures using a beam in the 5 - 20 micron (FWHM) range. However, many problems in structural biology suffer from poor S/N due to small (a few microns) crystals or larger inhomogenous crystals. In additional, theoretical calculations and experimental results have demonstrated that radiation damage may be reduced by using a micron-sized X-ray beam. At GM/CA CAT we are developing a sub-micron, low convergence beam to address these issues. The sub-micron beam capability will be developed on the existing beamline 23ID-D where the minimum beam size available to users is currently 5 microns in diameter. The target goals are a beam size of ~0.8 micron (FWHM) in diameter, with a beam convergence of less 0.6 milli-rads, a flux greater than 5×1010 photons/sec, and an energy range from 5 to 35 keV. Five optical systems will be compared: 1) a single set of highly demagnifying Kirkpatrick-Baez (K-B) mirrors, 2) multiple Fresnel Zone Plates (FZP), 3) a set of K-B mirrors focusing to a secondary source that is imaged by another set of K-B mirrors, 4) a set of K-B mirrors focusing to a secondary source that is imaged by a FZP, 5) a horizontal focusing mirror focusing to a secondary source that is imaged by another horizontal mirror together with a vertical focusing mirror. Here we will present the results of a design optimization based on ray trace simulations (SHADOW), flux calculations (XOP), and experimental results on 23ID.

Paper Details

Date Published: 9 September 2011
PDF: 8 pages
Proc. SPIE 8129, Novel Optical Systems Design and Optimization XIV, 81290E (9 September 2011); doi: 10.1117/12.894173
Show Author Affiliations
Zunping Liu, Argonne National Lab. (United States)
Shenglan Xu, Argonne National Lab. (United States)
Derek W. Yoder, Argonne National Lab. (United States)
Robert F. Fischetti, Argonne National Lab. (United States)

Published in SPIE Proceedings Vol. 8129:
Novel Optical Systems Design and Optimization XIV
R. John Koshel; G. Groot Gregory, Editor(s)

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