Bias in the measurement of radon gas using ionization chambers: Application to SIR.
Two main non-destructive techniques can be used to measure standard 222Rn gas ampoules: well-type ionization chambers and gamma-ray spectrometry, the former being used in the Système International de Référence (SIR) for international comparison purposes. The reliability of these techniques requires that the variability of the flame-sealed gas glass ampoules used have a negligible influence on the detector response. This variability is studied in this work by considering three parameters: the volume of the ampoule, the position of the sealing point and the thickness of the glass. Results showed that variability of the gas ampoules induced measurement bias larger than the uncertainty of the standard sources.
Development of the primary measurement standard for gaseous radon-222 activity.
The Korea Research Institute of Standards and Science (KRISS) has developed a primary system for the activity standardization of gaseous radon-222, based on the defined solid angle counting method. The size of adsorbed radon is determined by a Cyclone Storage Phosphor System, and a buffer chamber is introduced between the measurement chamber and the source for the purpose of gas purification. The measured activity of gaseous radon-222 and its associated measurement uncertainty obtained using the system are presented.
The Compton source efficiency tracing method in liquid scintillation counting: a new standardization method using a TDCR counter with a Compton spectrometer.
We describe a new standardization method in liquid scintillation counting based on the use of a temporary virtual tracer source created inside the scintillator by Compton interaction. The Compton tracer source is measured by the triple coincidence liquid scintillation counter after selection of the Compton events by a gamma-ray detector. The paper describes the principle of the method, the experimental setup and presents the results obtained by this method for the standardization of a (3)H solution. These results are compared with those obtained using the classical triple to double coincidence ratio method. Possible application of this new method for international comparisons is addressed.