Spectrometer for investigating cosmic X-rays

The spectrometer described was used on board the Cosmos 368 and 428 satellites to study cosmic X-rays in the energy range 2-20 keV. The instrument consisted of aluminum proportional counters filled with a mixture of 90% xenon and 10% methane with pressures up to 0.85 atm. Beryllium windows with a thickness of about 130 microns were used. The efficiency of the proportional counters was computed and spectra obtained by irradiating the counter with X-rays from Co-57 and Sn-119 were analyzed.