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A study was made of the cleavage and twinning character in single crystals of the chalcopyrite CuInSe2, copper indium diselenide, grown in the laboratory by a vertical Bridgman method. In this material, with a c/a ratio of 2.006, the two main cleavage orientations were found to be {101} and {112} (corresponding to the descriptions {201} and {111}, respectively, in a cubic lattice). The plane identifications were made by measuring angles between adjacent cleaved surfaces and verifying the orientations by X-ray Laue and diffractometry. Cleavage was also found less frequently in a {110} plane, but here microscopic examination of the surface revealed it to consist of ridges in a <110> direction, where the microplanes on either side of the ridge edge were {112} planes. Twinning in the grown crystals was found, by angle measurements and X-ray diffraction, to occur along {112} planes, which is similar to the result in face-centred cubic, diamond and zinc blende lattices, where they are the corresponding {111} planes.

As amorphous selenium based flat panel detectors gain more interest for direct, real-time x-ray imaging, we report in this paper the performance of such a detector by ANRAD Corporation. This new detector is based on a 1536 x 1536 array of amorphous silicon TFT pixels coupled with a 1000 m selenium converter biased at 10 V/rim. Each 150 tm x 150 tm pixel is made of a thin film transistor (TFT), a storage capacitor and a collecting electrode having a geometrical fill factor of 77 % and an effective fill factor of nearby 1 00 %.New TFT architecture and high speed electronics allow operation of this new detector under a large range of conditions from low dose fluoroscopy (few pR/frame) to DR and it supports frame rates from single shot to 60 fps. Image lag following x-ray excitation was measured to be very low.Key imaging parameters for this real time x-ray detection system such as: detective quantum efficiency (DQE), signal to noise ratio (SNR) and modulation transfer function (MTF) were measured. These results together with frames extracted from a low dose fluoroscopy sequence and an anthropomorphic phantom image will be presented.The measurements show that the dynamic performance of this new detector is very well suited for real time imaging in fluoroscopic and/or cardiac applications.