A Large Area (300 cm2) Gas Scintillation Proportional Counter for X-Ray Astronomy

A large area gas scintillation proportional counter (GSPC) developed for use as a spectrometer in X-ray astronomy is presented. A crude laboratory version of the xenon cell coupled to a 9 cm diameter ruggedised photomultiplier, has an energy resolution of ~ 11% FWHM at 6 keV over a total geometric area of ~ 300 cm2. The instrument has a high rejection ability for charged particles present in a space environment. A rejection efficiency for Co60 induced events of ~ 90% was achieved, over the energy range 1-20 keV, for an X-ray acceptance of ~ 80%. These results show that the GSPC is a credible improved alternative instrument to a proportional counter with which to study cosmic X-ray sources.