BIPM Key Comparison Research Articles

Comparison BIPM.RI(I)-K6 of the standards for absorbed dose to water of the LNE-LNHB, France and the BIPM in accelerator photon beams

Main textA key comparison has been made between the absorbed dose to water standards of the Laboratoire National Henri Becquerel (LNE-LNHB), France and the BIPM in accelerator photon beams. The results show the standards to be in agreement within the standard uncertainty of the comparison of 5.9 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.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).

Calibration of reference solar cells at standard test conditions

Main textThe EURAMET.PR-S5 intercomparison of the short circuit current of reference solar cells at standard test conditions was carried out as star type comparison. In total 6 participants with seven facilities took part, 1 from Europe (PTB/Germany with two facilities: the established DSR facility as pilot lab and the new Laser-DSR facility as participant) and 5 outside Europe (NIM/China, VNIIOFI/Russia, KRISS/South Korea, A-STAR/Singapore, ITRI/Chinese Taipei). Therefore, this comparison can be considered as a worldwide one as all NMIs world-wide that had built up facilities for the primary ISTC-calibration of reference solar cells when the measurements started, participated.For the calculation of the reference value of the supplementary comparison no participant had to be excluded and the used weighted mean with cut-off has been supported by all participants.The unilateral Degrees of Equivalence (DoE) calculated for each participant are fully 100 % consistent with their standard uncertainties. The largest En-value is 0.61 and therefore significant smaller than 1. The chi-square test is fully satisfied with 2.09 < χ2(5) = 11.07. Thus, the DSR method is highly suitable for the calibration of reference solar cells according to the short circuit current at standard test conditions.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 CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

APMP key comparison of absorbed dose to water for 60Co, APMP.RI(I)-K4

Main textThe APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K4 key comparison of absorbed dose to water for 60Co between 2009 and 2010. Fourteen standards laboratories took part in the comparison. Three commercial cavity ionization chambers were used as transfer instruments and circulated among the participants. Nearly all the measured calibration coefficients for each ionization chamber were within one standard uncertainty (as estimated by the laboratory) of the comparison mean for that chamber, indicating reasonable agreement amongst the participants. Three participants (ARPANSA, PTB and NMIJ) were used to link the results to the BIPM through the ongoing bilateral BIPM.RI(I)-K4 comparison. Through this link the degree of equivalence (the ratio to the BIPM Key Comparison Reference Value and its uncertainty) was calculated for each non-linking laboratory to show the calibration capabilities. For the 9 eligible participants, this degree of equivalent ratio fell within 3.3 parts in 103 of unity, well within the combined standard uncertainty in all cases.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).

Bilateral comparison of 10 V standards between the NSAI-NML (Ireland) and the BIPM

Main textAs part of the ongoing BIPM key comparison BIPM.EM-K11, a comparison of the 10 V voltage reference standards of the BIPM and the National Standards Authority of Ireland - National Metrology Laboratory (NSAI - NML), Dublin, Ireland, was carried out in November and December 2020. The objective for NSAI-NML in participating in this comparison was to demonstrate the international equivalence of its DC voltage measurement results and to support their calibration and measurement capabilities (CMCs) published in the Key Comparison Database of the BIPM (KCDB).Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_8 (Z8) and BIPM_9 (Z9), were transported by freight to NSAI-NML. At NSAI-NML, the reference standard for DC voltage at the 10 V level consists of a group of characterized Zener diode-based electronic voltage standards. The output EMF (Electromotive Force) of each travelling standard was measured by direct comparison with the group standard.At the BIPM the travelling standards were calibrated, before and after the measurements at NSAI-NML, with the Josephson Voltage Standard, developed at the BIPM. The output EMF of each travelling standard was measured against the Josephson Voltage Standard (JVS). Results of all measurements were corrected for the dependence of the output voltages of the Zener standards on internal temperature and ambient atmospheric pressure.The comparison result is presented as the difference between the value assigned to a 10 V standard by NSAI-NML, at NSAI-NML, U NSAI-NML, and that assigned by the BIPM, at the BIPM, U BIPM, on the reference date of 2020/11/14, as U NSAI-NML - U BIPM = -2.99 µV; u c = 1.71 µVwhere u c is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realization of the volt at NSAI-NML, and the uncertainty related to the comparison.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 CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Key comparison BIPM.RI(I)-K7 of the air-kerma standards of the NMIJ, Japan and the BIPM in mammography x-rays

Main textA new key comparison has been made between the air-kerma standards of the NMIJ and the BIPM in mammography x ray beams. The results show the standards to be in agreement at the level of the expanded uncertainty of 7.2 parts in 103. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database.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).

Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the GUM, Poland, and the BIPM in medium-energy x-rays

Main textA key comparison has been made between the air-kerma standards of the GUM and the BIPM in the medium-energy x-ray range. The results show the standards to be in agreement at the level of the expanded uncertainty of the comparison of 6.0 parts in 103. The results are analysed and presented in terms of degrees of equivalence, suitable for entry in the BIPM key comparison database.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).

Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between the EMI (United Arab Emirates) and the BIPM

Main textThis report gives the result of a bilateral comparison of resistance between the EMI (United Arab Emirates) and the BIPM carried out in 2020. Two 1 Ω and two 10 kΩ travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about one month, then for a period of about one month at the EMI, and finally again at the BIPM. The measurand was the 4 terminal dc resistance at low power. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparisons BIPM.EM-K13.a (for 1 Ω) and BIPM.EM-K13b (for 10 kΩ).The results from the EMI and the BIPM were found to be in good agreement, with a difference D smaller than the relative expanded uncertainty Uc (95% confidence, k = 2) giving D = -0.057 × 10-6, Uc = 0.400 × 10-6 for 1 Ω and D = 0.017 × 10-6, Uc = 0.194 × 10-6 for 10 kΩ.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 CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM.EM-K13.a and 13.b) between the NSAI-NML (Ireland) and the BIPM.

Main textThis report gives the result of a bilateral comparison of resistance between the NSAI-NML (Ireland) and the BIPM carried out from November 2020 to March 2021. Two 1 Ω and two 10 kΩ travelling standards belonging to the BIPM were used. The comparison was carried out with an 'A-B-A' pattern of measurements; the standards were measured first at the BIPM for a period of about one month, then for a period of about one month at the NSAI-NML, and finally again at the BIPM. The measurand was the 4 terminal dc resistance at low power. The BIPM was the pilot laboratory, and the comparison forms part of the ongoing BIPM key comparisons BIPM.EM-K13.a (for 1 Ω) and BIPM.EM-K13b (for 10 kΩ).The results from the NSAI-NML and the BIPM were found to be in good agreement, with a difference D smaller than the relative expanded uncertainty U c (95% confidence, k = 2) giving D = - 0.081 × 10-6, U c = 0.180 × 10-6 for 1 Ω and D = 0.069 × 10-6, U c = 0.424 × 10-6 for 10 kΩ.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 CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on the CIPM key comparison CCAUV.V-K5

Main textThe results of the fifth CIPM key comparison (KC) in the area of vibration, here concerning sinusoidal acceleration, are presented.This comparison was intended to build the foundation for subsequent regional key comparisons over the extended frequency range from 10 Hz to 20 kHz. Measurement results reported by 14 participants for magnitude and phase shift of complex charge sensitivity of single ended and back-to-back accelerometers were compared. A key comparison reference value has been defined for each type of artifact, and the respective Degrees of Equivalence are reported. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).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 CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on SIM.L.K1.2007.1 bilateral comparison (length) 2018-2019: calibration of gauge blocks by optical interferometry

Main textThis bilateral SIM key comparison on calibration of gauge blocks by interferometry (SIM.L-K1.2007.1) was carried out between CENAM (México) and INTI (Argentina). Its scope is to support and maintain the claimed Calibration and Measurement Capability (CMC) by the participants, which regularly offer the service of gauge block calibration by optical interferometry. The comparison was held from first half of 2018 to second half of 2019, and involved the measurement of eleven steel gauge blocks-eight in the range of short gauge block and three in the range of long gauge block. The reference values for each nominal length were taken as the arithmetic mean. The results of both participants are in good agreement with the reference values for all the gauge blocks measured. This makes the present comparison exercise valid to provide evidence of the participants' competence. The results also provides evidence to support the CMC claims of the participants in gauge block calibration by optical interferometry and for those service that stems out of this key technique as required by the CIPM Mutual Recognition Arrangement (CIPM MRA).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 CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report for supplementary comparison APMP.QM-S15: carbon dioxide in nitrogen at 1000 μmol/mol

Main textCarbon dioxide (CO2) in nitrogen was one of the first types of gas mixtures performed at an international key comparison. The comparison dates back to 1998 (CCQMK1a) [1]. Since then, many National Metrology Institutes (NMIs) have developed Calibration and Measurement Capabilities (CMCs) for these mixtures. The international comparison of CO2 at ambient level through CCQM-K52 was compared in 2007 [2]. Recently, NMIs in the APMP region have focused on developing emission standards for regulating CO2 released by various powered vehicles such as automobiles (motor cars). At the 2017 APMP meeting, several NMIs requested a CO2/N2 comparison to establish their own standards related with automotive regulation, which was to be coordinated by KRISS. Consequently, this comparison provides a CMC for APMP regional NMIs to develop CO2/N2 CMC claim.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 CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report for supplementary comparison APMP.QM-S9.2017: 100 μmol/mol of carbon monoxide in nitrogen

Main textCarbon monoxide (CO) in nitrogen was one of the first types of gas mixtures used in an international key comparison. This comparison dates back to 1998 (CCQM-K1a) [1]. Another key comparison on carbon monoxide is the CCQM-K51 at the lower amount fraction of 5 μmol/mol. Since then, many National Metrology Institutes (NMIs) have developed Calibration and Measurement Capabilities (CMCs) for these mixtures. Recently, NMIs in the APMP region have actively participated in international comparisons to provide domestic services. At the 2017 APMP meeting, several NMIs requested a CO comparison to establish CO/N2 certification for supporting industrial needs, which was to be coordinated by KRISS. Consequently, this supplementary comparison provides an opportunity for APMP regional NMIs to meet their industrial needs. It is a replica of APMP.QM-S9.[2]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 CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Force AFRIMETS supplementary comparison AFRIMETS.M.F-S2

Main textThe Regional Metrology Organization AFRIMETS Technical Committee in Mass and related Quantities (TCM) Working Group Force (WGF) met in July 2018 in Enugu Nigeria during the 12th General Assembly (GA) and made a decision to carry out an AFRIMETS supplementary comparison for the unit of force. This comparison, named the AFRIMETS.M. F-S2 supplementary comparison, in the force range of 250 kN and 500 kN. This comparison was planned to demonstrate the degree of equivalence between the national standards of force and to provide evidence for the Calibration and Measurement Capability (CMCs) claimed by the participating National Metrology Institutes (NMIs) in the AFRIMETS region, and particularly the who did not participate in the global CCM.F-K2 KC. The AFRIMETS TCM approved that KEBS of Kenya to serve as the pilot laboratory. and PTB of Germany to would be link laboratories. Although not part of the AFRIMETS region, PTB from EURAMET was invited to participate and provided the reference values while NMISA provided the transfer standards used during the comparison.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 CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The CCRI(II)-K2.Fe-55.2019 key comparison of activity concentration measurements of a 55Fe solution

Main textA comparison of the activity concentration of an 55Fe solution was organized by the POLATOM under the auspices of the CCRI(II). The solution was sent to thirteen laboratories; ready-to-measure sources were also prepared using the same 55Fe solution in diffusive (polyethylene) vials and sent to twelve laboratories. Twelve measurement reports were received. The results, as well as relevant information on the measurement techniques, are presented and analysed in this paper. The differences in the results obtained from measurements in non-diffusive (glass) and diffusive vials are indicated.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).

APMP Key comparison report of reference air kerma rate for HDR 192Ir brachytherapy sources (BIPM KCDB: APMP.RI(I)-K8)

Main textThe APMP/TCRI Dosimetry Working Group performed the APMP.RI(I)-K8 key comparison of the reference air kerma rate for high-dose-rate (HDR) 192Ir brachytherapy sources between 2016 and 2018. Eight laboratories, including seven national metrology institutes (NMIs), took part in the comparison. Two commercial well-type chambers were used as transfer instruments and circulated among the participants. The results showed that the maximum difference between the participants and the BIPM, evaluated using the comparison data of the linking laboratories NMIJ and NRC, was less than 4%. The degrees of equivalence for the participants were calculated, so that results for the six non-linking laboratories may be included in the Key Comparison Database (KCDB).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).

Subsequent comparison of measurements of neutron source emission rate (2016-17) - CCRI(III)-K9.AmBe.2

Main textTo 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).

Supplementary comparison APMP.RI(I)-S1 of standards for absorbed dose to water in 60Co gamma radiation at radiation processing dose levels

Main textFour national standards for absorbed dose to water in 60Co gamma radiation at the dose levels used in radiation processing have been compared over the range 0.1 kGy to 50 kGy using alanine dosimeters of the Office of Atoms for Peace (OAP) as transfer dosimeters. The comparison was piloted by the OAP who also participated. Two laboratories from the original six were forced to withdraw due to equipment problems. The results at low doses (0.1 kGy) showed a much wider spread (up to 17%) than at the other doses, most likely as a result of random variations in the alanine readout at OAP at these dose levels. Results in the 0.1 kGy range were excluded from the analysis because the variation between the laboratories' doses is overshadowed by the variation in the readout of the alanine. Above 1 kGy the results indicated reasonable agreement between the laboratories, with the majority of results within 2 % of the reference value. All of these results were within two combined standard uncertainties of the reference value, with the exception of the INER at 50 kGy point which was within three combined standard uncertainties. Within the stated uncertainties, the results establish the equivalence of the laboratories at radiation processing levels, for the range in which they participated: NIS (3 - 10) kGy, NIM (3 - 30) kGy, INER (3 - 50) kGy, OAP (3 - 50) kGy.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).

Key comparison BIPM.RI(I)-K3 of the air-kerma standards of the ARPANSA, Australia, and the BIPM in medium-energy x-rays

Main textTo 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).

International comparison CCQM-K117 ammonia

Main textAt the highest metrological level, ammonia gas standards are commonly prepared gravimetrically as Primary Standard Mixtures or using a dynamic standard. This international key comparison addressed the measurement of the amount fraction ammonia in nitrogen, to support calibration and measurement services for mainly environmental applications. The nominal amount fraction was 14 μmol mol-1. The results in this Track C key comparison on the composition of biogas are generally good.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 CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Final report on supplementary comparison on step heights standards (APMP.L-S7)

Main textThis intercomparison is carried out for step height standards with nominal step sizes 8 nm, 18 nm, 88 nm and 10 µm using non-contact measurement methods, with four participating NMIs. Measurement observation from the pilot laboratory exhibit significant stability of step height standards. For each step height standard, the supplementary comparison reference value (SCRV) is determined using weighted mean, followed by calculation of En values for outlier identification. Further the outliers were excluded based upon the Birge Ratio consistency test. Measurement results from all the participating NIMs have been compiled in this report.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 CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).