A 3 x 6 arrayed CCD X-ray detector for continuous rotation method in macromolecular crystallography.

A 3 x 6 arrayed charge-coupled device (CCD) X-ray detector has been developed for the continuous-rotation method in macromolecular crystallography at the Photon Factory. The detector has an area of 235.9 mm x 235.9 mm and a readout time of 1.9 s. The detector is made of a 3 x 6 array of identical modules, each module consisting of a fiber-optic taper (FOT), a CCD sensor and a readout circuit. The outputs from 18 CCDs are read out in parallel and are then digitized by 16-bit analog-to-digital converters. The advantage of this detector over conventional FOT-coupled CCD detectors is the unique CCD readout scheme (frame transfer) which enables successive X-ray exposures to be recorded without interruption of the sample crystal rotation. A full data set of a lysozyme crystal was continuously collected within 360 s (180 degrees rotation, 3 s/1.5 degrees frame). The duty-cycle ratio of the X-ray exposure to the data collection time was almost 100%. The combination of this detector and synchrotron radiation is well suited to rapid and continuous data collection in macromolecular crystallography.