A semi-microscopic derivation of gas gain formula for proportional counters

Effect of air on gas amplification characteristics in argon–propane (1%)-based proportional counters for airborne radon monitoring

“…Consequently, one can expect that the electron attachment process will introduce only a negligible effect on the gas amplification characteristics of the proportional counter, even in the presence of an important fraction of electronegative gas molecules as in our present case (up to 10% of air, corresponding approximately to an oxygen concentration of about 21000 ppm). Under these conditions and according to the semimicroscopic gas-gain formula taken to its thirdorder approximation, the natural logarithm of the resulting gas gain A in a single-wire proportional counter is given by [16] Ln…”