Biological X-ray diffraction measurements with a novel two-dimensional gaseous pixel detector

In order to exploit the potential of modern X-ray diffraction studies to it s full extent, a new generation of appropriate detectors is required. Here, a small prototype (28 x 28 mm(2) active area) of a novel two-dimensional p ixel detector is presented which satisfies most of the requirements. It is based on a gaseous single-photon counter with asynchronous readout and inte rpolating position encoding, combining the advantages of a pure pixel reado ut (high local and global rate capability) with those of a projecting reado ut (small number of channels). In order to demonstrate the suitability of t his detector for X-ray diffraction applications, measurements at a synchrot ron radiation source have been performed recording diffraction patterns fro m different biological samples (rat tail tendon collagen, phospholipid and protein crystal). These measurements have proven the good spatial resolutio n, the high intensity precision and the high local rate capability. Moreove r, the single-photon readout was utilized in order to perform time-resolved measurements in the case of SAXS studies and to apply fine angular slicing in the case of protein crystallography. The detector has a high reliabilit y and robustness, particularly when compared with conventional gaseous dete ctors, and the technology used can be easily extended to large active areas .