Measurement of uniformity of activity distribution in wide area reference sources

Measurement of uniformity is one of the requirements for quality assurance in international standards for alpha and beta wide area reference sources. Investigated sources are made from anodized aluminium foils where the radioactivity is incorporated in a very thin surface layer. A new method of estimating the uniformity is presented which includes measurements with a commercial position sensitive multiwire proportional counter. The experimental part of the method consists of measuring the alpha or beta emission rate of the sources in respect to results of windowless counting. Efficiency and homogeneity of the detector have been determined for several alpha and beta nuclides. Intensified investigation of uniformity in anodized foils has improved the production process and quality of reference sources. (orig.)