Direct Determination of the Individual Concentrations of Radon Daughter Products in the Atmosphere by the Means of Delayed Coincidence Technique
The apparatus consists of a sampling head to hold an air filter mounted directly over a CsI(Tl) scintillation counter. The radioactivity on the air-filter is measured throughout the sampling period. By means of a pulse shape discrimination technique, the alpha pulses are discriminated against beta pulses. The count rate of 214Bi-214Po pair is determined by the beta-alpha delayed coincidence method, and the contribution of 218Po and 214Pb to the total activity can be determined by subtracting a constant ratio of this coincidence rate. Finally, the growth curves of the individual activities of the daughters are recorded by a multichannel counting rate meter. The degree of equilibrium between radon and its daughters in the atmosphere is determined accurately in short time intervals.
KeywordsCounting Efficiency Coincidence Event Equilibrium Ratio Radon Daughter Daughter Activity
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