Sealed proportional counters filled at atmospheric pressure as gamma ray detector

Sealed proportional counters filled at atmospheric pressure have some very attractive features such as long shelf and operating life, flat plateau, lower cost, feasibility of making in different sizes and shapes, in areas of β and γ detection, when compared with the widely used halogen quenched GM counters. A typical 45X4.5 cms. Φ detector has copper shell as cathode material, 40 micron central wire as anode and was filled with P10 (90% Ar+10% methane) gas at atmospheric pressure. It had a sensitivity of 0.5 cps/μR/h, a plateau length of 400 V and slope of 5% per 100 V. It is normally operated at 1750 V and coupled to a charge sensitive preamplifier with discriminator set for 25 mV. This detector was evaluated as background radiation monitor with respect to its sensitivity, stability, operation in field for prolonged time etc. The paper discusses some important features of this type of detector. (author). 1 tab