High-volume screen diffusion batteries and α-spectroscopy for measurement of the radon daughter activity size distributions in the environment

• Published in: Journal of aerosol science Vol. 17; no. 5; pp. 873 - 879
• Main Authors: Reineking, A., Porstendörfer, J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1986; Elsevier Science
• Subjects: Analysis methods; Applied sciences; Atmospheric pollution; Exact sciences and technology; Pollution; Alpha radiation; Screening; Particle size; Radioactive pollution; Spectrometry; Distribution; Detection threshold; Aerosols; Indoor pollution; Air pollution; Measurement method; Radioisotope
• ISSN: 0021-8502; 1879-1964
• DOI: 10.1016/0021-8502(86)90040-6

An experimental set-up is described which facilitates the measurement of radon daughter activity size distributions in the diameter size range 0.5–2000 nm at radon activity concentrations down to 5 Bq m −3. The radioactive aerosol particles of different sizes are separated simultaneously by means of a set of high-volume screen diffusion batteries (DB) operating at volumetric flow rates of ∼ 2 m 3 h −1. The activities are collected before and after each DB on membrane filters. During the sampling period and after the end of sampling the α-activities are measured with surface barrier detectors. Using a minimization method (SIMPLEX), the activity size distributions of RaA ( 218Po) and RaC/RaC′ ( 214Pb/ 214Po) are calculated by comparing the measured penetration values with simulated data. This least square method considers the penetration curves of the DBs, and the size distributions are approximated by a sum of log-normal distributions. Initial measurements in homes yield activity size distributions which have up to three modes with median diameters near 1, 20–80 and 100–300 nm.