Absolute high accuracy counting of 222Rn by liquid scintillation spectrometry

The pulse-height distributions from known amounts of Rn-222 and its daughters were measured as a function of the volume of the scintillator solution. Rn-222 and its daughters in the gaseous space above the liquid scintillator were found to produce the air luminescence counts which lead to errors in quantitative determination of Rn-222 by liquid scintillation counting unless necessary corrections for the counts are made. The errors inherent in the conventional measurement of Rn-222 using a liquid scintillation spectrometer has been evaluated. Method for correcting the air luminescence counts are also discussed. (orig.)