Improvements in scintillation counter stabilization technique and its applications

Spectrum stabilization techniques for use with scintillation counters based on the counting rate difference feedback are studied with the aim of developing a universal stabilization system which is readily applicable to any type of scintillation detectors. System performance of various types of stabilizers was evaluated using a theoretical approach. A simplified model of the stabilizers is proposed to analyze various stabilizers systematically by using the linear control theory and to define clearly basic parameters affecting the overall performance. The random fluctuations in the system gain due to the very statistical nature in the measurements of counting-rate differences are treated on the statistical control theory for different types of stabilizers operated on either periodic or random reference pulses. The results thus obtained provide a quantitative basis of optimum selection of the basic parameters. Three different types of stabilizers which differ principally in the way of generation of the correction voltage were constructed, and the operating characteristics are experimentally investigated with special interest in line broadening due to counting statistics. The line broadenings measured are found to be in reasonable agreement with theoretical predictions. The use of pulsed light sources to stabilize the counter was also examined.