Coincidence summing corrections for the natural decay series in γ-ray spectrometry

Using a Monte Carlo code and a Markov formalism to describe the decay schemes, coincidence-summing correction factors can be calculated with a suitable accuracy. For two different measuring geometries and an HPGe detector, calculated and experimental correction factors have been shown to closely agree for 152Eu. The simulation method has subsequently been applied in assessing the need for coincidence-summing corrections for members of the uranium, thorium and actinium series measurable by γ spectrometry. Correction factors were calculated for predominant γ emissions significantly affected by coincidence-summing effects and the correctness of our calculations tested for environmental samples. The test makes it evident that in order to obtain reliable and unbiased activity values for some natural radionuclides coincidence summing cannot be neglected in environmental measurements at small source–detector distances.