CHARGE-COUPLED-DEVICE FIBER OPTIC TAPER ARRAY X-RAY-DETECTOR FOR PROTEIN CRYSTALLOGRAPHY

A large area charge-coupled device (CCD) based fiber optic taper array detector (APS-1) is installed at the insertion-device beamline of the Structural Biology Center at the Argonne Advanced Photon Source x-ray synchrotron. The detector is used in protein crystallography diffract ion experiments, where the objective is to measure the position and in tensity of x-ray Bragg peaks in diffraction images. Large imaging area , very high spatial resolution, high x-ray sensitivity, good detective quantum efficiency, low noise, wide dynamic range, excellent stabilit y and short readout time are all fundamental requirements in this appl ication. The APS-1 detector converts the 2-D x-ray patterns to visible light images by a thin layer of x-ray sensitive phosphor. The phospho r coating is directly deposited on the large ends of nine fiber optic tapers arranged in a 3x3 array. Nine, thermoelectrically cooled 1024x1 024 pixel CCDs image the patterns, demagnified by the tapers. After ge ometrical and uniformity corrections, the nine areas give a continuous image of the detector face with virtually no gaps between the individ ual tapers. The 18 parallel analog signal-processing channels and anal og-to-digital converters ensure short readout time and low readout noi se. We discuss the design and measured performance of the detector. (C ) 1998 Society of Photo-Optical Instrumentation Engineers.