A METHOD OF EVALUATION OF GAS GAIN IN PROPORTIONAL-COUNTERS

A method of evaluation of gas amplification in proportional counters, independently of gas gain measurements, is presented. The approach, particularly useful for high regions of the reduced electric field, (S = E/P), involves the fit of an analytic expression to all the S regions of the Townsend first ionization coefficient, (alpha/P), experimental data. This approach is also useful for the estimation of gas gain for established gas mixtures but of nonstandard proportions such as Ar/Xe/CO2. The constants obtained in the process were used to evaluate the fundamental gas gain equation. An appropriate formula was then found to fit the resulting data. A component of the method is the generation of (alpha/P) data for gas mixtures. Comparison of this work with various gas amplification models in the literature was effected. Physical phenomena which may be responsible for differences between calculated and experimental gas gain are discussed.