Design and Tests of a Detector for 222Rn in Soil-gas Measurements based on 222Rn Absorbing Scintillating Polymers

摘要

This work presents the development and first tests of a detector for continuous ^{222Rn in soil-gas measurements. It is based on scintillation spectrometry of 222Rn absorbed in scintillating polymers-plastic scintillator foils or plastic scintillation microspheres. The detector consists of an optical chamber optically coupled to a hermetic volume which contains small sized spectrometric components: a photomultiplier tube, high voltage supply, multi-channel analyzer and an outside board with chip-controlled sensors for pressure, temperature, humidity and an accelerometer. The detector is compact, portable and is designed for 222Rn in soil-gas in boreholes. Pilot laboratory studies of the performance of the detector are presented. They include: pulse-height spectrum characterization and energy resolution study with 239Pu source; counting efficiency study and study of the pulse-height spectrum of a plastic scintillator with 222Rn absorbed in it. The performance of the detector in the laboratory tests indicates that the approach to build a portable scintillation counter for 222Rn in soil-gas measurements in boreholes is feasible.}