Publications (2)3.93 Total impact
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Article: The Structural Biology Center 19ID undulator beamline: facility specifications and protein crystallographic results.
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ABSTRACT: The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5-0.6 A wavelength) with fluxes up to 8-18 x 10(12) photons s(-1) (depending on photon energy) onto cryogenically cooled crystal samples. The size of the beam (full width at half-maximum) at the sample position can be varied from 2.2 mm x 1.0 mm (horizontal x vertical, unfocused) to 0.083 mm x 0.020 mm in its fully focused configuration. Specimen-to-detector distances of between 100 mm and 1500 mm can be used. The high flexibility, inherent in the design of the optics, coupled with a kappa-geometry goniometer and beamline control software allows optimal strategies to be adopted in protein crystallographic experiments, thus maximizing the chances of their success. A large-area mosaic 3 x 3 CCD detector allows high-quality diffraction data to be measured rapidly to the crystal diffraction limits. The beamline layout and the X-ray optical and endstation components are described in detail, and the results of representative crystallographic experiments are presented.Journal of Synchrotron Radiation 02/2006; 13(Pt 1):30-45. · 2.73 Impact Factor -
Article: Area detector design Part II. Application to a modular CCD-based detector for X-ray crystallography
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ABSTRACT: The performance of laboratory and synchrotron CCD-based detectors for X-ray crystallography is modeled using expressions which describe both the detector and the experiment. The detectors are constructed from an array of identical modules, each module consisting of a phosphor X-ray-to-light convertor, a fiberoptic taper and a CCD. The performance is characterized by the detective quantum efficiency (DQE) and dynamic range (DR), and by four additional expressions; the detective collective efficiency (DCE), experimental detective quantum efficiency (XDQE), experimental detective collection efficiency (XDCE) and experimental dynamic range (XDR). These additional expressions provide a means for including experimental constraints in the design of the detector. For a crystallography detector, these constraints include the requirements that the detector a) integrate Bragg peaks to maximum precision, and b) efficiently collect data to high resolution (large Bragg angle). Results obtained using these expressions demonstrate the need for a detector with a relatively large area. In order to build a such a detector from a reasonable number of modules using currently available fiberoptic tapers and CCDs, tapers with a demagnification ratio of > 3:1 are required. A different conclusion would be arrived at if the DQE alone were considered, demonstrating the importance of this method.Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 325(3):558-567. · 1.21 Impact Factor
