Calibration of a 220Rn flow-through source

Abstract

Two reference methods have been established to calibrate the yield of a self-made 220Rn flow-through source. These reference methods include (a) a small scintillation cell flow-through method and (b) a gamma spectrometry method that takes advantage of an activated charcoal. The methods were validated theoretically and experimentally including intercomparison measurements. It is shown that the source is stable with a relative deviation less than 2.5% over 5 years, when the relative humidity ranged from 50 to 90%, and the temperature from 5 to 38 degrees C. The 220Rn monitor used in these reference methods is calibrated without a 220Rn gas source with determinate yield. On the basis of the calibration of the 220Rn source by the methods mentioned above, the accurate calibration of any 220Rn monitor by the self-made 220Rn source with stable yield is feasible.