E Anachkova | PubMed Health

PubMed1995

Effect of wire eccentricity on the performance of cylindrical proportional counters.

A theoretical and experimental investigation of the influence of eccentricity of the multiplication wire on the performance of cylindrical proportional counters is presented. The electric field in the counter is calculated by the method of images, and the Townsend formalism is used to derive the gas gain. The experimental determination of detector performance is carried out with 37Ar. The dependence of the gas gain and of the counter resolution on eccentricity is discussed, and it is shown that eccentricities up to 0.2 are of no concern in microdosimetric measurements with cylindrical proportional counters.

Radiometry↗

PubMed1994

Calibrating and testing tissue equivalent proportional counters with 37Ar.

A method for testing and calibrating tissue equivalent proportional counters with 37Ar is described. 37Ar is produced by exposure of argon in its normal isotope composition to thermal neutrons. It is shown that--up to volume ratios of 0.01 of argon to the tissue equivalent gas--there is no appreciable effect of the argon admixture on the function of the proportional counter. Conventional calibration methods with characteristic x-rays or with alpha-particles require modifications of the detectors, and they test only small sub-volumes in the counters. In contrast, argon permits calibrations and tests of the resolution that are representative for the entire counter volume and that do not require changes in detector construction. The method is equally applicable to multi-element proportional counters; it is here exemplified by its application to a long cylindrical counter of simplified design that is part of such a multi-element configuration.

Argon↗