Browsing by Author "Wilkins, SW"

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    The Australian diffractometer at the Photon Factory
    (American Institute of Physics, 1992-01) Barnea, Z; Creagh, GC; Davis, TJ; Garrett, RF; Janky, S; Stevenson, AW; Wilkins, SW
    Outlined are design features of a versatile high‐resolution two‐axis diffractometer that is being constructed for operation at the Photon Factory as an Australian national facility. The instrument features optional use of multiple‐imaging plates on a translating cassette to allow rapid recording of an almost complete range of data covering both the high‐angle and small‐angle scattering regime or alternatively the use of electronic detectors. The instrument will be capable of operation in various modes including the following: (i) high‐resolution powder diffraction with single‐channel counter and crystal analyzer, (ii) high‐resolution, high‐speed powder diffraction in the Debye–Scherrer mode with imaging plates as recording medium, either stationary or translating (for time‐dependent studies), (iii) small‐angle x‐ray scattering with imaging plates as recording medium, (iv) protein crystallography in screenless Weissenberg mode, and (v) two‐ or three‐axis single‐crystal diffractometry. The salient features of the instrument are the use of a double‐crystal sagittal focusing monochromator as primary monochromator together with the optional use of a condensing–collimating channel‐cut (CCCC) monochromator or other channel‐cut monochromator as secondary monochromator. The use of a CCCC monochromator enables fine tuning of beam position on sample, harmonic suppression, beam‐condensation, and variation of wavelength bandpass. Further features include the use of high‐precision incremental encoders on both axes, together with the capability of operating the whole diffractometer, including secondary monochromator and detectors, in vacuum of order 10−3 Torr in order to reduce absorption and parasitic scattering, and the use of a large camera radius (approximately 0.57 m) for the imaging plate cassette in order to increase angular resolution and signal to noise. © 1992 American Institute of Physics.
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    The Australian National Beamline Facility at the Photon Factory
    (American Institute of Physics, 1994) Garrett, RF; Cookson, DJ; Foran, G; Creagh, DC; Wilkins, SW
    The Australian National Beamline Facility has been installed at the Photon Factory, Tsukuba, Japan. The construction and operation of the facility has been funded by a consortium of Australian research organizations, universities, and government funding agencies, with the aim of providing Australian scientists with routine access to synchrotron radiation in the hard‐x‐ray region. The first experiments were performed at the ANBF in November 1992. The facility consists of a general purpose x‐ray‐beamline, including a simple two‐crystal monochromator, delivering either monochromatic x rays (range 5–20 keV) or white radiation to the experimental hutch. The main experimental instrument, a multiconfiguration diffractometer, has recently been installed at the beamline. This unique instrument combines vacuum operation and imaging plate detectors, and can be configured for high‐resolution powder diffraction (including a time resolved mode), protein crystallography, and triple‐axis experiments. In addition, the white or monochromatic beam can pass through the diffractometer to a secondary experimental table, where experiments such as EXAFS, Laue diffraction, topography, and microbeam measurements are performed. Details of the beamline, monochromator, and diffractometer optics and performance will be described, and an overview will be given of the experimental capabilities of the facility. © 1995 American Institute of Physics.
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    Direct current servo motor controlled four‐jaw slits for synchrotron radiation
    (American Institute of Physics, 1994-07-18) Garrett, RF; Cookson, DJ; Davey, P; Janky, S; Wilkins, SW
    A four‐jaw slit assembly and eight‐axis dc servo motor controller have been constructed and are in use at the Australian National Beamline Facility (ANBF) at the Photon Factory. Because of the vacuum operation of the beamline diffractometer, dc servo motors were preferred to stepper motors. Due to the large number of motors to be controlled, commercial dc servo controllers were unsuitable, and an eight‐axis controller was designed to be used in conjunction with the E500 CAMAC stepper motor controller. The system has been in use at the ANBF for about one year, and has allowed the integration of approximately 30 dc servo and stepper motors into a standard control system. © 1995 American Institute of Physics.
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    First experiments on the Australian Synchrotron imaging and medical beamline, including investigations of the effective source size in respect of x-ray imaging
    (International Union of Crystallography, 2010-01) Stevenson, AW; Mayo, SC; Häusermann, D; Maksimenko, A; Garrett, RF; Hall, CJ; Wilkins, SW; Lewis, RA; Myers, DE
    The Imaging and Medical beamline at the Australian Synchrotron achieved 'first light' in December 2008. Here, the first experiments performed on the beamline are reported, which involved both X-ray imaging and tomography studies for a range of samples. The use of a plastic-edge phantom for quantitative measurements of contrast and resolution proved to be very instructive and helped to confirm certain parameter values such as the effective horizontal source size, detector resolution and average X-ray energy for the polychromatic beam. © 2010, International Union of Crystallography
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    On the design for a versatile imaging and hard x‐ray beamline at the Australian Synchrotron: implementation of in‐line phase‐contrast imaging
    (American Institute of Physics, 2004-05-12) Wilkins, SW; Lewis, RA; Nesterets, Y; Garrett, RF; Mayo, SC; Nugent, KA; Parry, DJ; Siu, KKW; Stevenson, AS
    We outline key design features for a versatile imaging and hard X‐ray beamline for operation at the Australian Synchrotron. Special attention is paid to the implementation of in‐line phase‐contrast imaging using both the plane‐wave and spherical‐wave cases. © 2004 American Institute of Physics.
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    Powder diffraction using imaging plates at the Australian National Beamline Facility at the Photon Factory
    (American Institute of Physics, 1994-07-18) Garrett, RF; Cookson, DJ; Foran, GJ; Sabine, TM; Kennedy, BJ; Wilkins, SW
    A novel x‐ray diffractometer was installed at the Australian National Beamline Facility at the Photon Factory, Japan, in October 1993. One of the major capabilities of the instrument is high speed high resolution powder diffraction using imaging plate detectors. The diffractometer combines a two circle goniometer and a large cassette in which imaging plates can be loaded covering 320° of 2θ. The diffractometer is enclosed in a large vacuum chamber and can be operated in air, vacuum, or helium. Recently, powder data has been obtained from rutile (TiO2) and NBS Si 640b at wavelengths from 0.62 to 1.9 Å using imaging plates, and has been used to characterize the performance of the instrument. The data has been refined using the Rietveld method and R values of under 2% obtained. The resolution of the system varies from a minimum of about 0.04° to around 0.25° at 2θ angles around 160°, which is the equal of most synchrotron based powder diffractometers, and only slightly worse than that obtained using an analyzer crystal and scintillation detector. Using the imaging plates, 160° of data is simultaneously acquired in an exposure of about 10 min, compared to conventional counter diffractometer scans which routinely exceed 10 hours. © 1995 American Institute of Physics.