Peak Area Consistency Evaluation in Gamma Spectrometry

Abstract

Quantification of radionuclide activities in gamma spectrometry can be a challenging task. It depends on efficiency calibration, peak area calculation, nuclide decay data and correction factors, such as attenuation correction or true coincidence summing corrections. These quantities can present significant challenges to an accurate analysis. It is therefore desirable to have a way of assessing the quality of the radionuclide quantification that can be applied to samples with unknown activities and radionuclide compositions. A verification of the self-consistency of the analysis is one possible way of accomplishing this. In gamma spectrometry it is possible to calculate radionuclide activities using information from multiple gamma emission energies. This leads to an overdetermined system for which the solution can be used to look for inconsistencies. By calculating the recovered peak areas from the radionuclide activities and comparing these to the measured peak areas, outliers can be identified and by resolving these inconsistencies the analysis of the spectrum can be improved. This peak area consistency evaluation can be used to find incorrect shape of the efficiency calibration, missing interferences in the nuclide decay data, and point to peaks where the peak area calculation needs to be optimized. The performance of the method has been shown on a simple spectrum consisting of three radionuclides that are interfering with each other as well as a complex spectrum with unknown radionuclide composition and activities. The method will be integrated into a future version the Genie 2000 Gamma Spectroscopy Software.

Keywords

• gamma spectrometry
• self-consistency check
• genie 2000