The calibration of activated charcoal detectors in a small Rn-222 exposurechamber

Passive methods for radon measurements, especially those based on radon ads orption, require observation of proper calibration methods. The calibration method for diffusion-barrier charcoal detectors in a small (211 dm(3)) radon chamber has been proposed. The theoretical dependence of radon concentration vs. time inside the chamber during the exposure of char coal detectors has been obtained and verified experimentally. For this purp ose, the chamber volume as well as diffusion and adsorption parameters of t he detector were taken into consideration. For two types of detectors the conformity of calibration factors obtained i n two ways: calculated from theoretical points (550 or 683 Bq m(-3)/cps dep ending on detector type) and from experimental points (553 or 691 Bq m(-3)/ cps), was achieved. The proposed method makes it possible to calibrate different kinds of radon -adsorbing detectors (not only charcoal canisters) in small chambers withou t the necessity of using any reference, active device. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.