Models for Determining the Response of Passive Alpha Particle Detectors to Radon and Its Progeny in Cylindrical Detecting Volumes

Abstract

Abstract Many radon detectors exist in the form of a planar disc shaped alpha particle detector mounted in one end of a small cylindrical chamber. Models have been developed to determine the sensitivity of such detectors to radon exposure. A model, adapted from the Jacobi-Porstendorfer room models, is used to determine the partitioning of short-lived radon progeny between airborne and surface deposited states within the detecting volume. This is used in conjunction with Monte Carlo simulation to obtain the radon sensitivity. The use of these models with passive alpha track detectors is highlighted although they are of general applicability to passive detectors using other alpha detecting media. Using these models it is possible to design passive detectors with dimensions such that the alpha track densities may be optimised to a chosen radon exposure range. Validation of the modelling is presented in the form of comparisons between predicted and experimentally determined sensitivities of CR-39 alpha track detectors.