PARAMETRIZATION OF GAS AMPLIFICATION IN TISSUE AND MUSCLE-EQUIVALENT PROPORTIONAL-COUNTERS

Gas amplification in tissue- and muscle-equivalent proportional counters and air was determined by a double parametrisation analytic technique. An expression for the Townsend ionisation coefficient was first fitted to the experimental data from various workers, for the single gas components of the mixtures, to obtain the relevant constants. The ionisation coefficients for the mixtures were obtained by appropriate scaling, which enabled important parameters for these coefficients to be determined. These were then used to evaluate the fundamental gas gain equation. The resulting data were again fitted with a three-parameter analytic formula. The gas gain data are compared with experimental values from some authors. The alpha/P data obtained for methane tissue-equivalent gas are also compared with those resulting from the use of the Boltzmann equation. A discussion of factors that may account for differences between theoretical and experimental gas gain data is also presented.