Radon Emanation from Dust of Varying Composition and Size

Abstract

222 Rn emanating from environmental dust constitutes an important background component for many low-energy, low-rate experiments. Radon emanation rates from dust and rock, thus, are important for experiment planning. In this paper, we report measured radon emanation fractions (defined here as the ratio of the transient to the total radon progeny activity of a sample) for five types of dust differing in grain size and composition. This data was obtained using highpurity germanium detectors (HPGe), measuring emanated and non-emanated 222 Rn progeny activities and their temporal change. The range of observed radon emanation fractions ranges from 3.5 ± 1.9% and 16.1 ± 0.84%. The impact of the water, contained in the dust, might have on the emanation fraction was evaluated and found to be small. The data presented here do not show a clear correlation between dust particle size and emanation fraction, as hypothesized when starting this study. Our measurement results are compared to expectations of radon emanation models.