Activity determination of (59)Fe by 4π beta-gamma counting using liquid scintillation in the beta channel.
This paper reports on absolute activity measurements of iron-59 made at the National Metrology Institute of South Africa (NMISA) via 4π(LS)β-γ coincidence counting. The exercise formed part of an Asia Pacific Metrology Program (APMP) regional key comparison. Source data were analysed by the extrapolation technique for a number of gamma-ray window settings. In addition, a feasibility study was undertaken on a second technique; a non-extrapolation method based on a detection efficiency analysis. The reported activity concentration of the (59)Fe solution was determined with a relative uncertainty of 0.28% (k=1), the uncertainty being due mainly to the rate vs. efficiency fitting process. The result from the non-extrapolation method was lower than that given by extrapolation by 0.33%, within two standard deviations. Possible reasons for the small discrepancy are discussed.
['van Rooy|M W|MW|', 'van Staden|M J|MJ|', 'Lubbe|J|J|', 'Simpson|B R S|BRS|']
Iron-59 Extrapolation technique Non-extrapolation method Liquid scintillation coincidence counting