Van Wyngaardt, WMSimpson, BRS2007-02-072007-06-072007-02-072007-06-072006-10Van Wyngaardt, WM and Simpson, BRS. 2006. Absolute activity measurement of the electron-capture-based radionuclides Ce-139, I-125, Ir-192 and Zn-65 by liquid scintillation coincidence counting. Applied Radiation and Isotopes, vol. 64, 11 October, pp 1454-14580969-8043http://hdl.handle.net/10204/1570http://hdl.handle.net/10204/1570Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidence extrapolation technique. The advantage of using (LS) counting in the 4p channel is that self-absorption does not occur, leading to Auger electrons being detected with relatively high efficiency; I-125, Ir-192 and Zn-65 were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The Ce-139 measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since Ce-139 decays simply by electron-capture to the 166 keV excited state of 139La. This state de-excites through the emission of conversion electrons and g-rays. The detection efficiency analysis is based on a counting source being viewed by two phototubes in coincidence, with a single NaI(Tl) crystal detecting the g-rays this technique is a viable technique for the absolute activity measurement of electron-capture-based radionuclides. The efficiency data can generally be fitted with a linear function, particularly in the high-efficiency region, or by a low-order polynomial expression, giving rise to reliable extrapolated activity values. However the application of the method to 125I is more difficult due to the requirement of a proper background correction to the sum peak area. It is surmised that a NaI detector with improved resolution that better separates the sum peak will reduce the discrepancy observed in the more recent activity measurement164754 bytesapplication/pdfenCopyright: 2006 Elsevier Science LtdLiquid scintillationsCoincidence extrapolation techniqueRadionuclidesBIPMInternational bureau of weights measuresAPMPAsian pacific metrology programmeInorganic nuclear sciencesArticleVan Wyngaardt, W., & Simpson, B. (2006). Absolute activity measurement of the electron-capture-based radionuclides Ce-139, I-125, Ir-192 and Zn-65 by liquid scintillation coincidence counting. http://hdl.handle.net/10204/1570Van Wyngaardt, WM, and BRS Simpson "Absolute activity measurement of the electron-capture-based radionuclides Ce-139, I-125, Ir-192 and Zn-65 by liquid scintillation coincidence counting." (2006) http://hdl.handle.net/10204/1570Van Wyngaardt W, Simpson B. Absolute activity measurement of the electron-capture-based radionuclides Ce-139, I-125, Ir-192 and Zn-65 by liquid scintillation coincidence counting. 2006; http://hdl.handle.net/10204/1570.TY - Article AU - Van Wyngaardt, WM AU - Simpson, BRS AB - Four radionuclides with electron-capture-based decay schemes have been directly measured by a liquid scintillation coincidence extrapolation technique. The advantage of using (LS) counting in the 4p channel is that self-absorption does not occur, leading to Auger electrons being detected with relatively high efficiency; I-125, Ir-192 and Zn-65 were measured as part of international key comparisons held under the auspices of the International Bureau of Weights and Measures (BIPM). The Ce-139 measurements formed part of a regional comparison organized by the Asia Pacific Metrology Programme (APMP). Since Ce-139 decays simply by electron-capture to the 166 keV excited state of 139La. This state de-excites through the emission of conversion electrons and g-rays. The detection efficiency analysis is based on a counting source being viewed by two phototubes in coincidence, with a single NaI(Tl) crystal detecting the g-rays this technique is a viable technique for the absolute activity measurement of electron-capture-based radionuclides. The efficiency data can generally be fitted with a linear function, particularly in the high-efficiency region, or by a low-order polynomial expression, giving rise to reliable extrapolated activity values. However the application of the method to 125I is more difficult due to the requirement of a proper background correction to the sum peak area. It is surmised that a NaI detector with improved resolution that better separates the sum peak will reduce the discrepancy observed in the more recent activity measurement DA - 2006-10 DB - ResearchSpace DP - CSIR KW - Liquid scintillations KW - Coincidence extrapolation technique KW - Radionuclides KW - BIPM KW - International bureau of weights measures KW - APMP KW - Asian pacific metrology programme KW - Inorganic nuclear sciences LK - https://researchspace.csir.co.za PY - 2006 SM - 0969-8043 T1 - Absolute activity measurement of the electron-capture-based radionuclides Ce-139, I-125, Ir-192 and Zn-65 by liquid scintillation coincidence counting TI - Absolute activity measurement of the electron-capture-based radionuclides Ce-139, I-125, Ir-192 and Zn-65 by liquid scintillation coincidence counting UR - http://hdl.handle.net/10204/1570 ER -