Optimum characteristics of a propotional counter for a detection of the cosmic X -ray radiation from 2 to 25 keV

Optimum data are given of a proportional X-radiation counter with a square cathode shape. The counter is filled up with a mixture of Xe + 10% CH4 with pressure p = 250 tor; anode diameter is 0.1 mm with an internal cathode section of 60x60 mm. These data ensure high recording efficiency, energy and time resolution in case of suppression of a high energy particle background with a discriminator with respect to acceretion fronts. Coefficient of background suppression for 60sub(Co) and 137sub(Cs) isotopes is 90% with a discriminator threshold corresponding to transmission of 70% radiation with 2-25 kev energies. The background suppression coefficient for Xe + CO2 mixture is 1.5 - 2 times lower than for the working mixture. This result does not agree with the data already published and reflects some peculiar features of squarecathode counters