Helium-Butane Gas Mixtures as Fillings for Geiger-Müller Tubes

Abstract

GAS-FLOW counters are finding an increasing use, especially in automatic methods of counting carbon-14 and tritium in sample-changing devices, and in chromatogram scanners. We have investigated the performance of various mixtures of counting gases in order to determine the factors affecting the choice of an optimum mixture. The gases investigated consisted of helium containing 1.0–2.5 per cent of butane; helium bubbled through ethanol at 0° C. (containing about 1.6 per cent ethanol vapour); and, as standards of reference, ‘Tracerlab G–1 Geiger Gas’ (composition, according to manufacturers, principally helium, isobutane, and butadiene, in undisclosed proportions) and ‘Nuclear-Chicago Q–Gas’ (containing nominally 98.7 per cent helium + 1.3 per cent butane).