Reduction of the duration of the natural dead time of a 4 π gas ionization counter operating in geiger-muller

It Is only possible to benefit from the 100 per cent efficiency of a 4 π gas-ionisation detector operating in the Geiger-Muller regime (an efficiency which always appears difficult to attain in other detectors) if, one is able: - on the one hand to reduce considerably - on the other hand to fix very precisely the length at the real dead time of the system operating in the above conditions. Taking into account both the phenomena characteristic of the discharge in the regime under consideration, phenomena whose properties are described, and the geometrical conditions depending on the operation over a solid angle of 4 π, it is shown that with an exterior electronic system for cutting off the discharge for example in 30 nanoseconds, absolute 4 π G.M. measurements would become competitive with those now carried out almost in proportional conditions. Measurement results on sources of 5 x 103 emissions per second maximum obtained by the use of a system for which the interval between the passage of a particle and the moment when the device has been made insensitive is still 60 nanoseconds have made it possible to confirm these statements. (author)