Browsing by Author "Zimmerman, BE"

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    Comparison of triple-to-double coincidence ratio (TDCR) efficiency calculations and uncertainty assessments for Tc-99
    (Elsevier, 2010-07) Zimmerman, BE; Altzitzoglou, T; Rodrigues, D; Broda, R; Cassette, P; Mo, L; Ratel, G; Simpson, BRS; van Wyngaardt, WM; Watjen, C
    A comparison exercise for data analysis was recently conducted by the Liquid Scintillation Counting Working Group (LSCWG) of the International Committee on Radionuclide Metrology (ICRM) to evaluate the uncertainties involved in applying different analysis methodologies (including computer programs) for the triple-to-double coincidence ratio (TDCR) method. The goals of the comparison were to (1) study differences in calculation results from different TDCR analysis programs, (2) investigate differences in analysis techniques and uncertainty assessment philosophies between laboratories, and (3) study the effect of not taking asymmetry of photomultiplier tube (PMT) efficiencies into account on the calculated activity. To achieve this, a single set of TDCR data for the pure beta emitter 99Tc, was distributed to the participants, who analyzed the data according to their normal procedures and report the activity concentration of the 99Tc solution from their results. The results indicate that the presently used programs are generally able to calculate the same activity values, assuming that the correct input parameters are used and that not taking PMT asymmetry into account in the calculations can lead to significant (0.6% for 99Tc) errors in reported results. The comparison also highlighted the need for a more rigorous approach to estimating and reporting uncertainties. © 2010, Elsevier Ltd.
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    Results of an international comparison of activity measurements of 68Ge
    (Elsevier B. V., 2018-04) Cessna, JT; Fitzgerald, R; Zimmerman, BE; Laureano-Pérez, L; Bergeron, DE; van Wyngaardt, WM; Smith, ML; Jackson, TW; Howe, B; da Silva, CJ; Iwahara, A; da Cruz, PAL; Zhang, M; Liu, H; Liang, JC; Fréchou, C; Bobin, C; Cassette, P; Kossert, K; Nähle, O; Marganiec-Gałązka, J; Joseph, L; Ravindra, A; Kulkarni, DN; Yunoki, A; Sato, Y; Lee, KB; Lee, JM; Agusbudiman, A; Dziel, T; Listkowska, A; Tymiński, Z; Sahagia, M; Antohe, A; Ioan, MR; Luca, A; Krivosek, M; Ometakova, J; Javornik, A; Zalesakova, M; García-Toraño Martinez, E; Roteta, M; Mejuto, M; Nedjadi, Y; Juget, F; Yuan, MC; Yeh, CY; Yeltepe, E; Dirican, A; Keightley, JD; Pearce, AK
    An international key comparison, identifier CCRI(II)-K2.Ge-68, has been performed. The National Institute of Standards and Technology (NIST) served as the pilot laboratory, distributing aliquots of a 68Ge/68Ga solution. Results for the activity concentration, CA, of 68Ge at a reference date of 12h00 UTC 14 November 2014 were submitted by 17 laboratories, encompassing many variants of coincidence methods and liquid-scintillation counting methods. The first use of 4π(Cherenkov)β-γ coincidence and anticoincidence methods in an international comparison is reported. One participant reported results by secondary methods only. Two results, both utilizing pure liquid-scintillation methods, were identified as outliers. Evaluation using the Power-Moderated Mean method results in a proposed Comparison Reference Value (CRV) of 621.7(11) kBq g−1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6 mL ampoules to the BIPM to link the comparison to the International Reference System (SIR) which may lead to the evaluation of a Key Comparison Reference Value and associated degrees of equivalence. An international key comparison, identifier CCRI(II)-K2.Ge-68, has been performed. The National Institute of Standards and Technology (NIST) served as the pilot laboratory, distributing aliquots of a 68Ge/68Ga solution. Results for the activity concentration, CA, of 68Ge at a reference date of 12h00 UTC 14 November 2014 were submitted by 17 laboratories, encompassing many variants of coincidence methods and liquid-scintillation counting methods. The first use of 4π(Cherenkov)β-γ coincidence and anticoincidence methods in an international comparison is reported. One participant reported results by secondary methods only. Two results, both utilizing pure liquid-scintillation methods, were identified as outliers. Evaluation using the Power-Moderated Mean method results in a proposed Comparison Reference Value (CRV) of 621.7(11) kBq g−1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6 mL ampoules to the BIPM to link the comparison to the International Reference System (SIR) which may lead to the evaluation of a Key Comparison Reference Value and associated degrees of equivalence. An international key comparison, identifier CCRI(II)-K2.Ge-68, has been performed. The National Institute of Standards and Technology (NIST) served as the pilot laboratory, distributing aliquots of a 68Ge/68Ga solution. Results for the activity concentration, CA, of 68Ge at a reference date of 12h00 UTC 14 November 2014 were submitted by 17 laboratories, encompassing many variants of coincidence methods and liquid-scintillation counting methods. The first use of 4π(Cherenkov)β-γ coincidence and anticoincidence methods in an international comparison is reported. One participant reported results by secondary methods only. Two results, both utilizing pure liquid-scintillation methods, were identified as outliers. Evaluation using the Power-Moderated Mean method results in a proposed Comparison Reference Value (CRV) of 621.7(11) kBq g−1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6 mL ampoules to the BIPM to link the comparison to the International Reference System (SIR) which may lead to the evaluation of a Key Comparison Reference Value and associated degrees of equivalence. © 2021 Elsevier Ltd.
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    Results of the CCRI(II)-S12.H-3 supplementary comparison: comparison of methods for the calculation of the activity and standard uncertainty of a tritiated-water source measured using the LSC-TDCR method
    (Elsevier B. V., 2018-04) Cassette, P; Altzitzoglou, T; Anthohe, A; Rossi, M; Arinc, A; Capogni, M; Galea, R; Gudelis, A; Kossert, K; Lee, KB; Liang, J; Nedjadi, Y; Oropesa Verdecia, P; Shilnikova, T; van Wyngaardt, WM; Ziemek, T; Zimmerman, BE
    A comparison of calculations of the activity of a 3H2O liquid scintillation source using the same experimental data set collected at the LNE-LNHB with a triple-to-double coincidence ratio (TDCR) counter was completed. A total of 17 laboratories calculated the activity and standard uncertainty of the LS source using the files with experimental data provided by the LNE-LNHB. The results as well as relevant information on the computation techniques are presented and analysed in this paper. All results are compatible, even if there is a significant dispersion between the reported uncertainties. An output of this comparison is the estimation of the dispersion of TDCR measurement results when measurement conditions are well defined. © 2017 Elsevier Ltd.