Towards establishing traceability of results measured in specific counting conditions in gamma-ray spectrometry

Due to biased potassium activity results in the proficiency test soil samples, measurements of a set of control samples containing potassium compounds with known concentrations of potassium were performed in order to establish the traceability of potassium activity results in to the unit of mass. The radius and the mass of the control samples were equal to the radius and the mass of the proficiency test samples. The density of samples in both cases varied between 1 and 2 g/cm3. No influence of sample density on the potassium activity results could be detected at the accuracy level achieved. The source of disagreement could not be found within the participating laboratory.