The X-Ray Diffraction (XRD) beamline has been designed primarily for macromolecular crystallography. The light source is a multipole wiggler with a useful range from 4 to 22 keV. The optics consist in a vertical collimating mirror, a double-crystal Si(111) monochromator followed by a toroidal bendable focussing mirror. The tunability of the wavelength provides the opportunity to use the Multiwavelength Anomalous Diffraction (MAD) technique for solving the phase problem over a broad range of wavelengths, covering the absorption edges of all the heavy atoms commonly used in protein crystallography. The multipole wiggler spectrum includes high photon flux at low energies, allowing optimisation of the anomalous signal at the Sulphur, Xenon and Calcium edges. Helium purged beampath and helium based cryo-cooling at 100 K are available for data-collection experiments with long wavelengths.
The experimental station is equipped with the 165mm CCD detector from MarResearch, or the mar345 Imaging Plate. Crystals can be cooled to liquid nitrogen temperatures (routinely 100 K) with a 700 series Oxford Cryosystems cryocooler. Data collection is controlled through the Mar software running on a Linux PC workstation. Different Linux PC computers are available to the users. All the programs commonly userd for protein crystallography, including the HKL2000 suite (Xdisp, Denzo, Scalepack), Mosflm and XDS, are available for indexing, integrating, and scaling of the diffraction data.
Areas of research
On-line data analysis
The XRD beamline represents a complex data collection process, with specific processing, storage, anaysis and sharing and visualisation requirements. This kind of application requires both the support of a standard Grid computing environment, that is a virtual organisation, a set of distributed storage and computing resources and some resource brokering mechanism, a workflow definition and execution environment and the capability to integrate instruments (the detectors) and interactively collaborate in the data analysis process.Back to top