Absolute activity measurement of the electron-capture-based radionuclides ~(139)Ce, ~(125)I, ~(192)Ir and ~(65)Zn by liquid scintillation coincidence counting

摘要

Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidenceextrapolation technique. ~(125)I, ~(192)Ir and ~(65)Zn were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The ~(139)Ce measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since ~(139)Ce decays purely by electron-capture, the basic method is described for this radionuclide. Results and difficulties encountered are discussed and uncertainty budgets are presented.