Measurement of radon concentration in the air by PicoRad detectors

The paper presents the theory and methodology of radon concentration measurement in the air by PicoRad detector, which consists of a porous canister held securely near the top of a plastic vial. The porous canister contains a bed of a controlled mass of charcoal (1.3 g) and silica desiccant (0.9 g). To measure the radon concentration, the vial detector is exposed in the radon laden air for a certain interval of time (24, 48 or 72 h or longer), then the liquid scintillation cocktail is added into the vial and measured by the help of a liquid scintillation counter. In this paper both radon adsorption by the charcoal detector, while it is being exposed in the radon laden air, and desorption of radon from the charcoal into the liquid scintillation cocktail were investigated. As a result, some conclusions concerning the methodology of radon measurement by PicoRad detectors have been done. The desorption factor of radon from the charcoal into the liquid scintillation cocktail was determined. The radon concentration values in the air measured by PicoRad detectors were in good agreement with those obtained by an AlphaGuard radon monitor.