Microstrip proportional counters for SODART telescope on Spectrum Rontgen Gamma

Four position sensitive proportional counters will be delivered by the Danish Space Research Institute as focal plane instruments for the Soviet Danish Roentgen Telescope SODART. These detectors will incorporate the novel microstrip electrode design. This design has been tested with Xenon gas and an Fe-55 X-ray source. The energy resolution is better than 14 percent FWHM up to gas gains of 10,000, the rise time of pulses from X-ray events is fast, 100 ns, allowing for efficient background rejection by rise time analysis. A position resolution of 1 mm FWHM is easily obtained by resistive charge division of the signals from the cathodes and from a wire grid placed in front of the microstrip plate. The detector performs without significant degradation of gain or energy resolution at fluxes exceeding 10 exp 6/s sq cm and a total dose of 10 exp 11 photons.