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 ruggedized photomultiplier, has an energy resolution of about 11% FWHM at 6 keV over a total geometric area of about 300 sq cm. The instrument has a high rejection ability for charged particles present in a space environment. A rejection efficiency for Co-60 induced events of about 90% was achieved, over the energy range 1-20 keV, for an X-ray acceptance of about 80%.