Long-term determination of airborne radon progeny concentrations using LR 115 solid-state nuclear track detectors

Abstract

This paper described the establishment of lognormal distributions for the Jacobi room model parameters with a view to improve an existing method for long-term passive measurements of the equilibrium factor using LR 115 solid-state nuclear track detectors, namely, through the proxy equilibrium factor (Fp) method. Fp is defined as (C1 + C3)/C0 where C0, C1 and C 3 are the concentrations of 222Rn, and the airborne concentrations of 218Po and 218Po (or 214Bi), respectively. The studied Jacobi room model parameters included the ventilation rate λv, the aerosol attachment rate λa, the deposition rate λdu of unattached progeny and the deposition rate λda of attached progeny. The lognormal distributions generated more realistic distributions for the equilibrium factor F and the unattached fraction fp of the potential alpha energy concentration, and a much tighter relationship between F and F p, when compared with the traditionally used uniform distributions. With the new relationship between F and Fp, the accuracy of the Fp method to determine F from Fp is significantly improved. © 2011 Elsevier Ltd. All rights reserved.