Uncertainty Budget for 226Ra Activity Concentration in Water by Alpha Spectrometry

Yana Spasova,* Stefaan Pommé, Ljudmila Benedik, Uwe Wätjen
European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium
E-mail: yana.spasova@ec.europa.eu

Alpha-particle spectrometry is the most frequently used technique for the activity determination of alpha emitters, such as radium, uranium, plutonium, americium and thorium in environmental samples. In this paper an extensive uncertainty budget is presented for a typical alpha-particle spectrometry measurement of the 226Ra activity concentration in drinking water. The most influential parameters contributing to the uncertainty are investigated. The set-up used is a common alpha-spectrometry system for environmental samples using PIPS detectors. In particular, the influence of geometrical parameters as well as the activity distribution in the measured sources on the solid angle is scrutinised.

Keywords: Uncertainty, alpha-particle spectrometry, solid angle