An approach based on the SIR measurement model for determining the ionization chamber efficiency curves, and a study of and photon emission intensities

Michotte, C; Pearce, A; Cox, M G; Gostely, J.-J.

doi:10.1016/j.apradiso.2006.02.014

Cited by 20 publications

(10 citation statements)

References 21 publications

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“…All in all, the KCRVs derived from the PMM showed better consistency with the predicted values from the calculated efficiency of the SIR (Système International de Référence) [25]. The arithmetic mean is calculated from…”

Section: A3 Application To Data In the Kcdbmentioning

confidence: 61%

Determination of a reference value and its uncertainty through a power-moderated mean

Pommé

Keightley

2015

Metrologia

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A method is presented for calculating a key comparison reference value (KCRV) and its associated standard uncertainty. The method allows for technical scrutiny of data, correction or exclusion of extreme data, but above all uses a power-moderated mean that can calculate an efficient and robust mean from any data set. For mutually consistent data, the method approaches a weighted mean, the weights being the reciprocals of the variances (squared standard uncertainties) associated with the measured values. For data sets suspected of inconsistency, the weighting is moderated by increasing the laboratory variances by a common amount and/or decreasing the power of the weighting factors. By using computer simulations, it is shown that the PMM is a good compromise between efficiency and robustness, while also providing a realistic uncertainty. The method is of particular interest to data evaluators and organizers of proficiency tests.

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Section: A3 Application To Data In the Kcdbmentioning

confidence: 61%

Determination of a reference value and its uncertainty through a power-moderated mean

Pommé

Keightley

2015

Metrologia

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“…For energies above 73 keV, the differences between the data and model had a standard deviation of 0.7 % and a root mean square value of 0.9 %. The 201 Tl point (effective energy 72.5 keV) was 4.3 % below the model, however Michotte et al [ 12 ] have noted that the electron capture probabilities are in question, based on their own similar ionization chamber modeling. The uncertainty in the efficiency, based on the residuals, was taken to be a quadratic function defined by the points (E [keV], u [%]): (72, 1.5); (950, 0.8); (1836, 1.5).…”

Section: Methodsmentioning

confidence: 99%

Revision of the NIST Standard for 223 Ra: New Measurements and Review of 2008 Data

Zimmerman

Bergeron

Cessna

et al. 2015

J. RES. NATL. INST. STAN.

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After discovering a discrepancy in the transfer standard currently being disseminated by the National Institute of Standards and Technology (NIST), we have performed a new primary standardization of the alpha-emitter 223Ra using Live-timed Anticoincidence Counting (LTAC) and the Triple-to-Double Coincidence Ratio Method (TDCR). Additional confirmatory measurements were made with the CIEMAT-NIST efficiency tracing method (CNET) of liquid scintillation counting, integral γ-ray counting using a NaI(Tl) well counter, and several High Purity Germanium (HPGe) detectors in an attempt to understand the origin of the discrepancy and to provide a correction. The results indicate that a −9.5 % difference exists between activity values obtained using the former transfer standard relative to the new primary standardization. During one of the experiments, a 2 % difference in activity was observed between dilutions of the 223Ra master solution prepared using the composition used in the original standardization and those prepared using 1 mol·L−1 HCl. This effect appeared to be dependent on the number of dilutions or the total dilution factor to the master solution, but the magnitude was not reproducible. A new calibration factor (“K-value”) has been determined for the NIST Secondary Standard Ionization Chamber (IC “A”), thereby correcting the discrepancy between the primary and secondary standards.

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“…Strong non-linearities are observed for ICs filled with argon or a mixture of gases including xenon for which the response is enhanced at the energy of the K-edge of the gas. In such a case, a single polynomial is perhaps not ideal to model the photon efficiency over the whole energy range and a different set of basis functions, such as B-splines [19,20], may be more suitable [21].…”

Section: R I/amentioning

confidence: 99%

“…However, when using B-splines functions, such discontinuities can be dealt with [20]. For the same two methods, strong β + emitters are generally not included because the emission points of the annihilation γ rays can be very distinct from the actual source position, and this effect increases as the β + energy and emission probability increase [21]; as such, the use of these radionuclides would introduce a significant bias in the photon efficiency curve at 511 keV.…”

Section: R I/amentioning

confidence: 99%

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Uncertainty evaluation in activity measurements using ionization chambers

et al. 2015

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Pressurized re-entrant (or 4π) ionization chambers (ICs) connected to current-measuring electronics are used for activity measurements of photon emitting radionuclides and some beta emitters in the fields of metrology and nuclear medicine. As a secondary method, these instruments need to be calibrated with appropriate activity standards from primary or direct standardization. The use of these instruments over 50 years has been well described in numerous publications, such as the Monographie BIPM-4 and the special issue of Metrologia on radionuclide metrology (

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An approach based on the SIR measurement model for determining the ionization chamber efficiency curves, and a study of and photon emission intensities

Cited by 20 publications

References 21 publications

Determination of a reference value and its uncertainty through a power-moderated mean

Determination of a reference value and its uncertainty through a power-moderated mean

Revision of the NIST Standard for 223 Ra: New Measurements and Review of 2008 Data

Uncertainty evaluation in activity measurements using ionization chambers

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