Standardisation of iodine-123 and participation in the comparison BIPM.RI(II)-K4.I-123
Year: 2025
Type: article
Abstract: Iodine-123 was standardised by the 4π(e A ,X)-γ live-timed anti-coincidence counting technique, with liquid scintillation (LS) counting applied for the 4π channel. Seven LS sources were counted over 4 days. To trace the decay of impurities 125 I, 121 Te and 123m Te, one source was counted for an additional 9 times over 100 days. Fitting the extended dataset to the decay function for the component radionuclides provided impurity correction factors. The recorded data were corrected for background, live time, impurities and decay, and plotted as vs . Weighted least squares regression and extrapolation to provided the source activity. Data were fitted with a 3 rd order polynomial with the 2 nd order coefficient = zero to account for curvature present in the data. A 1 st order polynomial fit provided an activity concentration that was 1.02% higher. This primary standard was developed as part of ANSTO’s participation in the BIPM.RI(II)-K4.I-123 key comparison, using the Transfer Instrument of the International Reference System (SIRTI). The result that was submitted for participation in the inter-comparison was 0.85% higher than the result reported in this manuscript. With the latest re-evaluation, the standard uncertainty increased from 0.36% to 0.53%, mostly due to the non-linear extrapolation of the detection efficiency curve.
Source: Applied Radiation and Isotopes
Authors: W.M. van Wyngaardt, A.H.H. Bowan, M. Zarifi, C.M.B. Keevers, E.L. Clark, M.L. Smith, C. Michotte
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,220
OpenAlex ID: W4411582689