Detector With Charge-Coupled-Device Sensor For Protein Crystallography With Synchrotron X Rays

Abstract
A two-dimensional detector consisting of a 40-mm-diameter x-ray fluorescing phosphor, coupled with an image intensifier and lens to a CCD image sensor, was developed for protein crystallography with synchrotron x rays. The intense x radiation from a synchrotron source could, with a suitable detector, provide a complete set of diffraction images from a protein crystal before the crystal is damaged by radiation (2 to 3 min). The CCD-based detector was evaluated in an experiment with a rotating anode x-ray generator to determine its suitability in this application. Diffraction patterns from a lysozyme crystal obtained with this detector were compared to those obtained with film. The two images appear to be virtually identical. The flux of 104 x-ray photons/s was observed on the detector at the rotating anode generator. At the 6-GeV synchrotron being designed at Argonne National Laboratory, the flux on an 80 X80 mm2 detector is expected to be >109 x-ray photons/s. The projected design of such a synchrotron detector shows that with a CCD pixel full-well capacity of 7 X105 diffraction peaks containing 3 X 106 x rays could be recorded. With an exposure time of 0.5 s and an additional 0.5 s readout time of a 512 X512 pixel CCD, the data acquisition time per frame would be 1 s so that ninety 1° diffraction images could be obtained, with approximately 1% precision, in less than 3 min.

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