Calibration of Neher-Harper Counter Circuit for Accurate Comparison of β- or γ-Ray Sources

This is the authors' abstract. We don't add key points for this paper.

The conditions affecting the reproducibility of a thin-walled all-glass type counter used with the Neher-Harper quenching circuit have been investigated. The plate voltage and grid bias on the quenching tube are the most critical factors, and experimental arrangements for holding them constant are described. An upward drift in counting rate is noted at rates of the order of 100 per sec., and methods for minimizing the effect of this drift on the accuracy of the measurements are described. A new method of calibrating a counter circuit is used. The activity of a sample of radon is measured under the same geometrical conditions at different times, and by use of the accurately known half-life of radon, the counting losses at various speeds are determined. A variation of the multiple-addition method of calibration is also used with concordant results. It is found that with proper precautions the counter can be used to measure counting rates in the range from 30 to 200 per sec. with an accuracy of 0.2 to 0.3 percent.