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First results from a macromolecular crystallography system with a polycapillary collimating optic and a microfocus X‐ray generator
Author(s) -
Gubarev Mikhail,
Ciszak Ewa,
Ponomarev Igor,
Gibson Walter,
Joy Marshall
Publication year - 2000
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889800001837
Subject(s) - collimated light , monochromator , optics , full width at half maximum , materials science , diffraction , generator (circuit theory) , x ray , focal length , flux (metallurgy) , physics , lens (geology) , power (physics) , laser , wavelength , quantum mechanics , metallurgy
The design and performance of a high‐flux X‐ray crystallography system, optimized for diffraction measurements from small macromolecular crystals, is described. This system combines a microfocus X‐ray generator [40 µm full width at half‐maximum (FWHM) spot size at a power level of 40 W] and a short focal length ( F = 2.6 mm) polycapillary collimating optic, and produces a small‐diameter quasi‐parallel X‐ray beam. Measurements of the X‐ray flux, divergence and spectral purity of the resulting X‐ray beam are presented. The X‐ray flux through an aperture of 250 µm diameter produced by the microfocus system is 16 times higher than that from a 3.15 kW rotating‐anode generator equipped with a pyrolytic graphite monochromator. Diffraction data from lysozyme test crystals collected with the microfocus X‐ray system are of high quality and can be reduced with standard crystallographic software, yielding an overall merging factor R sym ≤ 6%. Significant additional improvements in flux are possible, and plans for achieving these goals are discussed.