Proportional counters: Physical and technical aspects, applications in radiation protection measurements

Proportional counters are frequently considered to be just a kind of transition stage between an ionization chamber and a GM-counter. This view is mainly based on the presentation of pulse heights versus applied voltage that can be found in most text books. However, a closer look on the physical phenomena taking place in a counter tube reveals that the voltage is by no means the only criterion for the detector to be operating in the proportional or in the geiger region. This is, on the contrary, determined in practice by the creation and absorption of UV photons in the counting gas on the one hand, and by the release of electrons by ions arriving at the cathode on the other hand. These relations are being investigated in the first part. The results are applied to derive consequences for better construction and practical operation of proportional counters. In practical use proportional counters prove to be a quite original kind of radiation detector. The many possible variations of sizes and shapes, and the favourable operational properties have opened a broad field of applications in radiation protection measurements. This is shown in the second part, giving many specific examples. A short third part points out where the future development will be going. (orig./HP)