Portable battery-powered continuous airborne (sup 222)Rn sampler

摘要

The Polyport, designed at the Environmental Measurements Laboratory (EML) for deployment in atmospheric balloons or remote areas, was laboratory and field tested to determine its effectiveness in collecting (sup 222)Rn gas in dry and humid air. Twelve 6-cm long tubes containing 0.4 g of Carboxen(trademark)-564 a hydrophobic beaded carbon molecular sieve (BCMS) material efficiently adsorbs airborne (sup 222)Rn under dynamic sampling conditions of 1--2 hr duration. The exposed sorbent is later weighed for water uptake, transferred and counted in a low background liquid scintillation (LS) counter that can detect alpha and beta emitting (sup 222)Rn progeny with a maximum counting efficiency of 5 cpm per dpm. Each sorbent tube can be gamma counted if it contains sufficient adsorbed (sup 214)Pb and (sup 214)Bi activity. The variables tested were sampling flow rate, temperature, sampling time and relative humidity (RH).