Statistical uncertainties associated with multiplexed sampling with a continuous radon monitor.
One common type of continuous radon monitor is a flow-through device that counts alpha emissions from a gas sample as it passes through a scintillation cell. To improve the ability of this type of continuous radon monitor to track time-varying radon concentrations, a forward-marching data analysis procedure that considers the production, deposition, and decay of radon progeny as a function of time had been previously developed. This paper examines some of the statistical issues associated with using such a monitor and applying the forward-marching analysis procedure to the problem of multiplexed radon concentration samples. It uses Monte Carlo simulations, together with limited experimental data, to perform: 1) an examination of the potential bias of the forward-marching analysis technique; 2) an examination of a simplified methodology for evaluating concentration-measurement uncertainty for various radon concentration histories; and 3) an analysis of an example application of the simplified uncertainty analysis to multiplexing of soil-gas samples. The results of these analyses indicate: 1) that the forward-marching analysis technique is relatively unbiased, at least at concentrations > 148 Bq m-3 for time steps longer than 120 s; 2) that a simplified uncertainty analysis procedure based upon Poisson statistics and no error correlation between intervals provides generally acceptable estimates of measurement uncertainty; and 3) that such a monitor and analysis technique can be successfully employed to measure multiplexed soil-gas samples, but is not appropriate for multiplexing of most building concentrations.
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Indoor Environment Program, Lawrence Berkeley Laboratory, Berkeley, CA 94720.
Bonnefous
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D016902:Air Pollution, Indoor / Q000032:analysis*; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000706:statistics & numerical data; D011886:Radon / Q000032:analysis*; D013997:Time Factors
D011886:Radon