Discussion on the liquid scintillation method for radon in water and some examples of measurements

It is generally for measuring radon in water to use the liquid scintillator which has relatively large solubility for radon. The method which is so-called liquid scintillation method, has several weakness that radon gas escapes in a process of making the vial sample and/or with the elapsed time after making the vial sample. This affects to the precision and reproducibility. The authors compared three different process in the method; one is the extracted-by-solvent method (namely, extract method), two is the method that sample water is directly enclosed with toluene scintillator in a vial (two layer method), and three is the method that sample water is directly enclosed with ''picofluor'' scintillator in a vial (picofluor method). These methods were examined about the following term; the reasonable ratio between sample water and scintillator, the detection limit, the error dispersion, easiness, and quickness. The authors concluded that the picofluor method was the best method exclusive of detection limit. (author)