The Counting Losses in Geiger-Müller Counter Circuits and Recorders

Abstract

The counting losses due to the finite recovery time of Geiger-Müller counter circuits and recorders are investigated. A description and critique of several experimental methods is given. The parallel method reported here gives the most accurate results. By this method the counting losses in a system consisting of a Geiger-Müller counter coupled by means of a Neher-Harper circuit to a scale-of-one recorder were determined. The method compares the counts registered by the scale-of-one against those registered by a vacuum tube scale-of-128 in parallel with it. The resolution times of both the scale-of-one and the G-M, Neher-Harper combination are thus found. The theoretical equations of Ruark and Brammer and Alaoglu and Smith are verified. The limitations and applicability of the Schiff-Volz formulation are also determined. Departures from the Ruark-Brammer formula for the Neher-Harper circuit are found at high counting rates. A corrected formula is derived. The speed of the Neher-Harper type of extinguishing circuit, determined in these experiments, is compared against the maximum counting speed possible with G-M counters. It is found that such circuits already approach the speed of the G-M tube itself. Existing vacuum tube scaling circuits and frequency meters are shown to be already faster than the G-M tube itself. The methods for correcting recorders and counter circuits for counting losses are given. These losses amount to about 20 percent for a Cenco recorder and one percent for most G-M counters at input rates of 1000 counts per minute. The losses increase rapidly with the input counting rate.