HIGH-PRESSURE MWPC FOR HARD X-RAY ASTRONOMY

The second generation of detectors for hard X-ray astronomy essentially requires large area detectors and efficient background discrimination. A conventional scheme is to use an array of Nal scintillator crystals with a large number of photomultipliers, a light collection system and individual guard counters for charged particle rejection. High pressure proportional counters can provide an alternative instrument with comparatively higher performance in terms of effective area and background discrimination at lower cost and weight. A 900 cm**2 detector, with a thin aluminum window (0. 16 g/cm**2) and a 4 atm xenon filling has been developed and tested on a balloon flight.