LARGE-AREA, 2-D, HIGH-PRESSURE MWPC FOR-WIDE ANGLE X-RAY-DIFFRACTION

Multi Wire Proportional Counters (MWPCs) possess all the required feat ures for recording X-ray diffraction patterns: large area, high detect ive quantum efficiency (DQE), low dead time and simultaneous spatial a nd spectral information. However, their suitability as wide-angle diff raction is compromised by an effect known as parallax broadening. This phenomenon is due to the low density of the gas in the detector, wher e photons incident at large angles following the same ray may interact at different points along it and therefore appear as different coordi nates in the image. One way to reduce this effect is by increasing the density of the absorbing medium in order to ensure the photons intera ct in a thinner gas layer, this can be achieved if the pressure of the gas in the detector is increased. We present here a high-pressure (5 bar) detector which has the potential to bring the desirable features of a photon counting system to wide-angle diffraction experiments. The preliminary results are also presented.