Main text Since 2019, 2 laboratories have submitted 2 samples of 161 Tb to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Tb-161. Recently, the NPL (United Kingdom) participated in the comparison and the key comparison reference value (KCRV) has been evaluated for the first time. The degrees of equivalence between each equivalent activity measured in the SIR and the updated KCRV have been calculated and the results are given in the form of a table. A graphical representation is also given. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

When verifying the validity of the exponential-decay law through 137 precise decay rate measurement series at various nuclear laboratories, minor violations have been observed in the shape of annual cycles in the residuals with different amplitudes and phase shifts. The timing and amplitude of these deviations have been compared with local weather data and it appears that ambient humidity is highly correlated with the observed instabilities in these radioactivity measurements. In fact, when compensating the residuals for a linear relationship with absolute humidity in air, most of the annual cycles are no longer statistically significant. As a result, the validity of the exponential-decay law can now be demonstrated with even higher fidelity.

Main text Since 2014, 3 laboratories have submitted 3 samples of 223Ra to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Ra-223. The NPL (United Kingdom), the PTB (Germany) and the LNE-LNHB (France) participated in the comparison and the key comparison reference value (KCRV) has been calculated for the first time. The degrees of equivalence between each equivalent activity measured in the SIR and the KCRV have been calculated and the results are given in the form of a table. A graphical presentation is also given. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

In the summer of 2017, the Système International de Référence Transfer Instrument (SIRTI) of the Bureau International des Poids et Mesures (BIPM) was hosted by the National Research Council of Canada (NRC) in Ottawa, Canada. This SIRTI visit was unique in many aspects. It was the first visit of the SIRTI to Canada. NRC was the first National Metrological Institute (NMI) to perform comparisons of four isotopes (99mTc, 18F, 64Cu and 11C) during a single two-week period. Finally, this was the first official measurement of 11C in the SIRTI. The NRC had performed a primary standardization of 11C in February of 2017 and calibrated its Secondary Standard Ionizing Radiation Chamber System (SSIRCS) in preparation for the SIRTI comparison. Two primary Liquid Scintillation methods (CIEMAT/NIST and TDCR) were employed and the results agreed. The stock material was received from a local cyclotron in the form of a 11C-labelled sodium acetate (NaC2H3O2). Three ampoules were prepared for the purposes of comparison; one concentrated from the bulk material and two derived from a single dilution. Some inconsistency was evident due to a weighing problem for one of the ampoules containing the diluted solution, whose measurements were excluded from the analysis. The other two ampoules' results were consistent within their respective uncertainties. The SIRTI was very stable and the final BIPM report will detail the stability checks, performance and behaviour of the SIRTI during its measurement campaign in Canada. There is still no Key Comparison Reference Value (KCRV) for 11C as NRC is the first participant. However, during a test of the SIRTI at NPL in 2014, an equivalent SIRTI activity was measured as 9.87(5) kBq which was consistent with MonteCarlo predictions for 11C in the SIRTI of 9.867(15) kBq. The NRC SIRTI equivalent activity for 11C agrees within uncertainty with these results. This offers encouragement to other NMIs to request a 11C comparison given the consistency of experimental results from NRC and test results from the National Physical Laboratory, UK (NPL) and the BIPM. Finally a half-life measurement was determined from the NRC measurement of multiple half-lives of a 11C ampoule and was found to be 20.332(40)min. From the SIRTI measurements at NRC, the half-life was derived as 20.328(13) min. This is smaller but consistent with the DDEP recommended value of 20.361(23)min.

Holmium-166 is a high-energy beta(-)-emitter radionuclide (similar to 1.8 MeV) with a short half-life (similar to 26.8h) that offers great potential as an alternative to Y-90 for the treatment of liver cancer based on radioembolization. The possibility of quantitative Single Photon Emission Computed Tomography (SPECT) imaging of the main gamma-ray emission at 80.6 keV, in addition to strong paramagnetic properties suitable for Magnetic Resonance Imaging (MRI), complement this therapeutic potential. The present paper describes the measurements carried out in three European radionuclide metrology laboratories for primary standardization of Ho-166 and new determinations of X- and gamma-ray photon-emission intensities in the framework of the European EMPIR project MRTDosimetry. New half-life measurements were also performed.

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)kBqg−1, based on 14 results. The degrees of equivalence and their associated uncertainties are evaluated for each participant. Several participants submitted 3.6mL 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.

In 2016, comparisons of activity measurements of 18F and 64Cu using the Transfer Instrument of the International Reference System (SIRTI) took place at the National Institute of Standards and Technology (NIST, USA). This is the first SIRTI comparison for 64Cu. Ampoules containing about 27 kBq of 18F and 100 kBq of 64Cu solutions were measured in the SIRTI for about 5 and 1.5 half-lives, respectively. The NIST standardized the activity in the ampoules by ionization chamber measurements traceable to 4π(LS)β−γ anticoincidence measurements. The comparisons, identifiers BIPM.RI(II)-K4.F-18 and BIPM.RI(II)-K4.Cu-64, are linked to the corresponding BIPM.RI(II)-K1.F-18 and BIPM.RI(II)-K1.Cu-64 comparisons and degrees of equivalence with the respective key comparison reference values have been evaluated. The NIST replaces its earlier degree of equivalence for 18F obtained in the frame of the CCRI(II)-K3.F-18 comparison in 2001. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

This paper is concerned with the modeling of the transmission of beta rays through thin foils in planar geometry based on the plane source concept, using Monte Carlo simulation of electron transport and least squares fitting. Applications of modeling results for calculating the efficiency of large-area beta sources, transmission coefficient of beta rays through thin foils and the beta detection efficiency of large-area detectors used in surface contamination measurements are also presented.

Nuclear counting is affected by pulse pileup and system dead time, which induce raterelated count loss and alter the statistical properties of the counting process. Fundamental equations are presented to predict deviations from Poisson statistics due to non-random count loss in nuclear counters and spectrometers. Throughput and dispersion of counts are studied for systems with pileup, extending and non-extending dead time, before and also after compensation for count loss. Equations are provided for random fractions of the output events, applicable to spectrometry applications. Methods for loss compensation are discussed, including inversion of the throughput equation, live-time counting and loss-free counting. Secondary effects in live-time counting are addressed: residual interference from pileup in systems with imposed dead times and errors due to varying count rate when measuring shortlived radionuclides.

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.

In 2008, the National Physical Laboratory (NPL) submitted one sample of known activity of 56Mn to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Mn-56. The value of the activity submitted was about 290 kBq. There is now one result in the BIPM.RI(II)-K1.Mn-56 comparison. The key comparison reference value (KCRV) has been evaluated for the first time using the NPL result and a BIPM result dating November 1978. The degree of equivalence between the NPL equivalent activity measured in the SIR and the KCRV has been calculated and is reported. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

A novel method has been developed for the activity measurement of large-area beta reference sources. It makes use of two emission rate measurements and is based on the weak dependence between the source activity and the activity distribution for a given value of transmission coefficient. The method was checked experimentally by measuring the activity of two ((60)Co and (137)Cs) large-area reference sources constructed from anodized aluminum foils. Measurement results were compared with the activity values measured by gamma spectrometry. For each source, they agree within one standard uncertainty and also agree within the same limits with the certified values of the source activity.

Two new participations in the BIPM.RI(II)-K1.Lu-177 comparison have been added to the previous results and this has produced a revised value for the key comparison reference value (KCRV), calculated using the power-moderated weighted mean. A link has been made to the CCRI(II)-K2.Lu-177 comparison held in 2009 through the NPL and IRMM who participated in both comparisons. Two NMIs used the K2 comparison to update their degree of equivalence. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the remaining two NMIs in the BIPM.RI(II)-K1.Lu-177 comparison and the nine other participants in the CCRI(II)-K2.Lu-177 comparison. A graphical presentation is also given.

We propose to measure half-lives in Ru by using (d, pγ) reactions. At low energies, single-particle and seniority isomers emerge. The nucleus is placed in a region of triaxiallity, which often gives rise to sub-nanosecond isomers. The present proposal is focused on the lifetime of the intruder state and single-particle low-spin states. 1 Motivation Ru is located on the Segré chart between its heaviest stable isotope Ru [1, 2] and the most exotic 117,118,119Ru nuclei, produced in relativistic fission [3, 4, 5]. Being just on the edge of the line of β-stability, only few experimental methods can be used to populate its excited states. So far, the nucleus was studied in the Tc β-decay [6], Ru(d,p) reaction [8, 7] and n-capture on Ru [10, 9]. However, these reaction mechanisms are highly selective and populate only low-spin states. In the 1990s the high-resolution high-granularity multidetector γ-ray arrays become available, which have enabled the use of induced fission reactions for γ-ray spectroscopy, providing the opportunity to fill in the gap of transitional nuclei situated between the line of beta stability and the most exotic neutron-rich nuclei produced in fission. By using induced fission reaction, the intruder negative-parity band in Ru was observed for the first time and extended to (31/2−) [11]. 1.1 Intruder states Being the first neutron-rich odd-mass nucleus in the ruthenium isotopic chain, Ru is crucial for the understanding of the structure of the more exotic ruthenium nuclei. For example, in [11]

As the pre-calibrated sample containers used for activity assay in the two NPL secondary standards ionisation chambers are being phased out, suitable replacements have been identified. Characterisation checks have been carried out on the new ISO ampoules and a long-term recalibration schedule has been devised. Around 40 calibration factors have been determined so far and comparison of ion chamber responses for the two ampoule types showed variations of up to 7% for low energy photon emitting radionuclides.

Since 2009, four national metrology institutes (NMI) have submitted four samples of known activity of Cu-64 to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Cu-64. The values of the activity submitted were between about 3 MBq and 260 MBq. There are now five results in the BIPM.RI(II)-K1.Cu-64 comparison. A key comparison reference value (KCRV) has been calculated for the first time for this nuclide. The degrees of equivalence between each equivalent activity measured in the SIR and the KCRV have been calculated and the results are given in the form of a table. A graphical presentation is also given.

Two new participations in the BIPM.RI(II)-K1.Lu-177 comparison have been added to the previous results and this has produced a revised value for the key comparison reference value (KCRV), calculated using the power-moderated weighted mean. A link has been made to the CCRI(II)-K2.Lu-177 comparison held in 2009 through the NPL and IRMM who participated in both comparisons. Two NMIs used the K2 comparison to update their degree of equivalence. The degrees of equivalence between each equivalent activity measured in the International Reference System (SIR) and the KCRV have been calculated and the results are given in the form of a table for the remaining two NMIs in the BIPM.RI(II)K1.Lu-177 comparison and the nine other participants in the CCRI(II)-K2.Lu-177 comparison. A graphical presentation is also given.

The purposes of this study were to create national activity standards of (64)Cu, to make possible the definition of an international key comparison reference value and to determine the decay data in order to improve the decay scheme. Four laboratories measured the activity of a (64)Cu solution; these results were compared through the International Reference System. Moreover, the laboratories carried out new measurements of the photon emission intensities and of the half-life. A new decay scheme was derived from these new values and the previously published ones.

An international Key Comparison of (177)Lu has recently been carried out. Twelve laboratories performed assays for radioactivity content on aliquots of a common master solution of (177)Lu, leading to eleven results submitted for entry into the Key Comparison Database of the Mutual Recognition Arrangement. A proposed Comparison Reference Value (CRV) was calculated to be 3.288(4)MBq/g using all eleven results. Degrees of equivalence and their uncertainties were calculated for each laboratory based on the CRV. Most of the values reported by the participating laboratories were within 0.6% of the CRV.