Operation of proportional counters under high gas gain, high working gas pressure in mixed field of radiation

Abstract

It was noted that gas gain depends on type of detected radiation and for beta particle is higher by 6–8 % than for X-ray . Over some value of current flowing through the counter (IC—critical current) the reduction in gas gain due to space charge defined by the time of evacuation of positive ions is observed. The value of IC for different counter geometries and different mixture pressures was measured. It limits the rate capability of the detector for fixed gas gain. Over some value of gas gain (AC—critical value of gas gain) non-proportionality due to self inducted space charge effect is observed. The value of AC was measured as a function of working gas pressure for different counter geometries. Measurements were made for gas compositions Ar+20% CO2 and Ar+6.4% CO2+2.5% N2, for mixture pressures from 0.05 to 0.65MPa and for different counter geometries.