Long-term measurements of unattached radon progeny concentrations using solid-state nuclear track detectors

We described a method for long-term passive measurements of unattached fraction fp of the potential alpha energy concentration of radon progeny from a set of measured (f1, f2, f3) values, where fi=Ci/C0 (i=1, 2, 3), and C0, C1, C2 and C3 were the concentrations of 222Rn, and the airborne concentrations of 218Po, 214Pb and 214Bi, respectively. Jacobi room model parameters were randomly sampled from their lognormal distributions to search for (f1′, f2′, f3′) sufficiently close to (f1, f2, f3) and to determine fp. There was 99% and 88% chance obtaining an estimated fp value within 50% and 30% of the true value, respectively. - Highlights: ► We proposed a method for passive measurements of the unattached fraction fp. ► It required information on concentrations of 218Po, 214Pb and 214Bi in air. ► Jacobi room model parameters were sampled from their lognormal distributions. ► Reproducing concentrations of 218Po, 214Pb and 214Bi gave estimates on fp. ► 99% of estimated fp values were within 50% of the true value.