Determination of 222 Rn absorption properties of polycarbonate foils by liquid scintillation counting. Application to 222 Rn measurements

Proceeding of the 20th International Conference on Radionuclide Metrology and its Applications (ICRM), 8-11 June 2015, Vienna, Austria. Organizer TU Wien. Editors Franz-Josef Maringer, Dirk Arnold, Uwe Wätjen.International audienceThis work demonstrates that a Liquid Scintillation Counting (LSC) technique using a Triple to Double Coincidence Ratio counter with extending dead-time is very appropriate for the accurate measurement of Rn-222 activity absorbed in thin polycarbonate foils. It is demonstrated that using a toluene-based LS cocktail, which dissolves polycarbonates, the Rn-222 activity absorbed in thin Makrofol N foil can be determined with a relative standard uncertainty of about 0.7%. A LSC-based application of the methodology for determination of the diffusion length of Rn-222 in thin polycarbonate foils is proposed and the diffusion length of Rn-222 in Makrofol N (38.9 +/- 1.3 gm) and the partition coefficient of Rn-222 in Makrofol N from air (112 +/- 12, at 20 degrees C) and from water (272 +/- 17, at 21 degrees C) are determined. Calibration of commercial LS spectrometers for Rn-222 measurements by LSC of thin polycarbonate foils is performed and the minimum detectable activities by this technique are estimated