Metrologia最新文献

{"title":"CCQM-K160: Platinum Group Elements in Automotive Catalyst","authors":"Sarah Hill, Heidi Goenaga Infante, John Entwisle, Stanislav Strekopytov, Christian Ward-Deitrich, Simon Cowen, Olaf Rienitz, Anita Roethke, Volker Goerlitz, Ursula Schulz, Carola Pape, Jochen Vogl, Maren Koenig, Radojko Jacimovic, Paola Fisicaro, Tongxiang Ren, Song Wang, Panshu Song, Haifeng Li, Maré Linsky, Egor Sobina, Hernán Ezequiel Lozano, Mabel Puelles, Randa Yamani and Conny Haraldsson","doi":"10.1088/0026-1394/61/1a/08011","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/08011","url":null,"abstract":"The platinum group elements (PGEs) play an important role in reducing emissions from automotive vehicles through their use in catalytic convertors but also for catalysis in the pharmaceutical industry. The immense economic value of platinum (Pt), palladium (Pd) and rhodium (Rh) highlights the importance of highly accurate measurements. Therefore, there is a need for National Metrology Institutes (NMIs) and Designated Institutes (DIs) to demonstrate measurement capability in this space. A pilot comparison (CCQM-P63) for precious metals in automotive catalyst took place in 2006, but with a limited number of institutes participating. Furthermore, this study was performed over 17 years ago. Therefore, there was a need to maintain existing capability and demonstrate new capability in a key comparison, in order to claim calibration and measurement capability claims (CMCs). With the core capability matrix, this study falls into the \"Difficult to dissolve metals/metal oxides\" which will support CMC categories 8 (Metal and metal alloys), 9 (Advanced materials) and 14 (Other materials). Eleven NMIs and DIs participated in the Key Comparison CCQM-K160 Platinum Group Elements in Automotive Catalyst. Participants were requested to evaluate the mass fractions of Pt, Pd and Rh in mg/kg in an unused autocatalyst material (cordierite ceramic base). The Key Comparison Reference Values (KCRVs) and Degrees of Equivalence (DoEs) were calculated utilising the NIST Decision Tree for the measurands. The participants utilised a number of sample preparation and analytical methods including hot plate digestion, microwave digestion and sodium fusion, followed by either atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectroscopy (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS) detection. Several calibration techniques were used, namely external calibration, standard addition, isotope dilution mass spectrometry (IDMS) and an exact matching procedure. Additionally, one participant employed instrumental neutron activation analysis (INAA) with k0 standardisation which is a direct solid analysis method. The majority of participants claimed traceability to NIST primary calibrants or their own CRMs. Furthermore, several matrix CRMs were included or spiked samples for quality control. All institutes were required to determine the dry mass fraction using the stipulated protocol. The NIST decision tree was implemented for the calculation of the KCRVs and DoEs. The participant results overall showed good agreement with the KCRV, despite the variety of dissolution procedures and measurement techniques for this highly complex matrix and challenging measurands. Successful participation in CCQM-K160 demonstrated measurement capabilities for the determination of mass fraction of Pt, Pd and Rh in the mg/kg range and will support broad scope CMC claims for a wide range of challenging matrices. To reach the main text of this paper, click on ","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"41 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141549502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"171Yb+ optical clock with 2.2×10−18 systematic uncertainty and absolute frequency measurements","authors":"A Tofful, C F A Baynham, E A Curtis, A O Parsons, B I Robertson, M Schioppo, J Tunesi, H S Margolis, R J Hendricks, J Whale, R C Thompson and R M Godun","doi":"10.1088/1681-7575/ad53cd","DOIUrl":"https://doi.org/10.1088/1681-7575/ad53cd","url":null,"abstract":"A full evaluation of the uncertainty budget for the ytterbium ion optical clock at the National Physical Laboratory (NPL) was performed on the electric octupole (E3) transition. The total systematic frequency shift was measured with a fractional standard systematic uncertainty of . Furthermore, the absolute frequency of the E3 transition of the 171Yb+ ion was measured between 2019 and 2023 via a link to International Atomic Time (TAI) and against the local caesium fountain NPL-CsF2. The absolute frequencies were measured with fractional standard uncertainties between and , and all were in agreement with the 2021 BIPM recommended frequency.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"63 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of local realizations of Silver freezing-point temperatures between NMIA and NMIJ AIST","authors":"M-K Ho and J V Widiatmo","doi":"10.1088/0026-1394/61/1a/03004","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/03004","url":null,"abstract":"The key comparison CCT-K4.1 was initiated on the request of the National Measurement Institute, Australia (MNIA) to re-link their standards to the Consultative Committee for Thermometry (CCT) Key Comparison (KC) and facilitate the NMIA CMC submission. National Metrology Institute of Japan, Japan (NMIJ) provided the linkage to the CCT-K4 at the temperature of the freezing point of silver. At the time of the CCT-K4 NMIA (formerly CSIRO-NML) had only one silver cell and this was found to be contaminated shortly after completion. Subsequently, more silver cells were fabricated at different times to form an ensemble of five cells before the start of CCT.K4.1. In the CCT-K4.1 bi-lateral comparison, a silver cell provided by NMIA and used as the artefact and circulated in accordance with the pilot-participant-pilot scheme. It is standard practice for NMIJ to use argon at 6N purity and NMIA argon 5N purity to regulate the pressure in the silver cell. To mitigate this, the effect of different argon purity was assessed in the post-circulation measurements. First the comparison was made under 6N purity atmosphere to preserve the cell ambience after it left NMIJ then the measurement was repeated under 5N argon atmosphere. The linkage was based on the temperature of NMIJ reference Ag fixed point relative to the key comparison reference value (KCRV) of CCT-K4 at the Ag fixed point via the difference in temperature between the NMIA reference Ag fixed point and NMIJ reference Ag fixed point (links to the KCRV of the CCT-K4). The temperature difference between the standards of NMIA and the KCRV of the CCT-K4 was within the evaluated comparison uncertainties of the CCT-K4.1. This report provides detailed information on the comparison results, linkage mechanism, and the Degree of Equivalence of NMIA relative to the institutes having participated in the CCT-K4. 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 CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"9 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141549491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PAWG pilot study on quantification of total haemoglobin in blood","authors":"C Swart, P J Beltrão, S M Naressi Scapin, Y Bacila Sade, M Neves de Medeiros, J-S Jeong, Y Jin, Y Liu, L Feng, X Gong, L Feng, M Winchester, L Yu, C Arsene, A Schulze, R Ohlendorf and C Brauckmann","doi":"10.1088/0026-1394/61/1a/08010","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/08010","url":null,"abstract":"Under the auspices of the Protein Analysis Working Group (PAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a pilot study, CCQM-P201, was organised. Five National Metrology Institutes (NMIs) participated in this pilot study and provided a total of eleven measurement results using six different methods based on three different measurement principles. The purpose of this pilot study was to develop measurement capabilities for the accurate quantification of intact haemoglobin (Hb) whereby measurement results could be made directly traceable to the SI. The choice of protein resulted from its ability to be quantified via different measurement principles providing different routes of traceability. Hb also provided a model of an intact protein with a complex tetrameric structure which is often measured via quantification of a specific subunit or the incorporated haem group. To achieve appropriate results for the chosen measurand, it was necessary to distinguish between the whole protein and fragments of the tetrameric structure, such as dimers or monomers. The participants were encouraged to investigate several of the measurement methods available. This was considered particularly advantageous in this instance as various methods applied to the same analyte may assist in identifying possible previously unknown biases or interferences of the various methods. Hb is being used as a model system to build capacity in methods for the quantification of proteins with a molar mass ≤ 100 kDa in biological fluids in a concentration range > 1∙106 pmol/g. This was the first pilot study for the quantification of an inherent protein in blood with all the natural variations that protein shows in a clinical sample. The different methods applied by the participants included isotopic dilution (ID) organic mass spectrometry (MS) of specific peptides after tryptic digestion, species-specific ID inductively coupled plasma mass spectrometry (ICP-MS), post-column ID ICP-MS, quantification via total iron after chromatographic isolation of Hb and acid digestion as well as two optical methods. One of the latter was the reference method proposed by the International Committee for Standardisation in Haematology (ICSH) based on the conversion of Hb to hemiglobincyanide (HiCN), the other used the conversion of Hb with alkaline haematin detergent both followed by the measurement of spectroscopic absorbance. Considering the use of very different measurement techniques for the quantification of total Hb, the results are in good agreement with a reference value with corresponding expanded uncertainty of (120.6 ± 1.2) mg/g calculated as DerSimonian-Laird mean. However, the observed differences between the results are not completely reflected in the reported measurement uncertainties. The calculated interlaboratory standard deviation or Tau value (dark uncertainty) was approximately 3 % whilst the average reported measurement uncertainty was approximately half this (1.4 %).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"30 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bilateral comparison of 1.018 V and 10 V standards between SASO-NMCC (Saudi Arabia) and the BIPM, September to November 2023 (part of the ongoing BIPM key comparison BIPM.EM-K11.a and b)","authors":"S Solve, R Chayramy, M Stock, A Alrobaish and A Aljomaie","doi":"10.1088/0026-1394/61/1a/01005","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/01005","url":null,"abstract":"As part of the ongoing BIPM key comparison BIPM.EM-K11.a and b, a comparison of the 1.018 V and 10 V voltage reference standards of the BIPM and the SASO-NMCC (Saudi Arabia), from September to November 2023. Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_E (ZE) and BIPM_F (ZF), were transported by freight to the SASO-NMCC and back to the BIPM. In order to keep the Zeners powered during their transportation phase, a voltage stabiliser developed by the BIPM was connected in parallel to the internal battery. At the SASO-NMCC and the BIPM, the reference standard for DC voltage is a Programmable Josephson Voltage Standard (PJVS). The output electromotive force (EMF) of each travelling standard was measured by direct comparison with the primary standard. The final result of the comparison is presented as the difference between the values assigned to DC voltage standards by the SASO-NMCC, at the level of 1.018 V and 10 V, at the SASO-NMCC, USASO-NMCC, and those assigned by the BIPM, at the BIPM, UBIPM, at the reference date of the 30th of September 2023. USASO-NMCC - UBIPM = 0.06 V; uc = 0.05 V, at 1.018 V USASO-NMCC - UBIPM = 0.22 V; uc = 0.12 V, at 10 V where uc is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realisation of the volt at the BIPM and at the SASO-NMCC, 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).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"36 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bilateral comparison of 1.018 V and 10 V standards between INRIM (Italy) and the BIPM, November to December 2023 (part of the ongoing BIPM key comparison BIPM.EM-K11.a and b)","authors":"S Solve, R Chayramy, M Stock, P Durandetto and E Enrico","doi":"10.1088/0026-1394/61/1a/01004","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/01004","url":null,"abstract":"As part of the ongoing BIPM key comparison BIPM.EM-K11.a and b, a comparison of the 1.018 V and 10 V voltage reference standards of the BIPM and the INRIM (Italy), from November to December 2023. Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_7 (Z7) and BIPM_9 (Z9), were transported by freight to the INRIM and back to the BIPM. In order to keep the Zeners powered during their transportation phase, two additional external batteries were connected in parallel to the internal battery. At the INRIM and the BIPM, the reference standard for DC voltage is a Programmable Josephson Voltage Standard (PJVS). The output electromotive force (EMF) of each travelling standard was measured by direct comparison with the primary standard. The final result of the comparison is presented as the difference between the values assigned to DC voltage standards by the INRIM, at the level of 1.018 V and 10 V, at the INRIM, UINRIM, and those assigned by the BIPM, at the BIPM, UBIPM, at the reference date of the 1st of December 2023. UINRIM - UBIPM = 0.06 V; uc = 0.05 V, at 1.018 V UINRIM - UBIPM = 0.22 V; uc = 0.12 V, at 10 V where uc is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realisation of the volt at the BIPM and at the INRIM, 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).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"24 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The CCL-K11 ongoing key comparison. Final report for 2023","authors":"M Matus, H S Margolis, J Seppä, H Karlsson, C-H Hanquist, A J Lancaster, A J Lewis, M Brawer, M del Mar Pérez, M Bisi, J Hald and G Zechner","doi":"10.1088/0026-1394/61/1a/04002","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/04002","url":null,"abstract":"Six lasers from six national metrological institutes (NMIs) were compared in the year 2023 as part of the CCL-K11 ongoing key comparison, initiated by the 13th meeting of the Comité Consultative des Longueurs (CCL) in 2007. The absolute frequency of theses lasers was measured in three different node laboratories following the technical protocol for CCL-K11. All are practical realisations of the definition of the metre according to the MeP for the definition of the metre. Five standards are He-Ne-lasers stabilized on the f component of the R(127) 11-5 transitions of molecular iodine 127I2 with a wavelength of approximately 633 nm. The sixth standard is a fibre laser stabilized to the P(16) (ν1+ν3) transition of molecular acetylene 13C2H2 with a wavelength of approximately 1542 nm. The technical protocol was deliberately designed to accommodate artefacts of different wavelengths in a common framework. The results of these measurements are compiled in the present report. The comparison reports, as communicated by each participant, are included in the main document. This document constitutes the thirteenth final report for the ongoing key comparison CCL-K11. 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).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"116 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Final report for CCT comparison of ITS-90 realisations above the silver point using two transfer radiation thermometers and a set of high temperature fixed-point blackbody cells","authors":"Helen McEvoy, Dave Lowe, Graham Machin, Maria José Martin, Klaus Anhalt, Jӧrg Hollandt, Mohamed Sadli, Frédéric Bourson, Yoshiro Yamada, Naohiko Sasajima, Xiaofeng Lu, Yongshim Yoo, Howard Yoon, Charles Gibson, Andrew Todd and Donald Woods","doi":"10.1088/0026-1394/61/1a/03003","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/03003","url":null,"abstract":"This report outlines the equipment, measurement method, results and uncertainties associated with the participant measurements for the Consultative Committee of Thermometry Key Comparison K10 (CCT-K10), \"ITS-90 realisations above the silver point using two transfer radiation thermometers and a set of high temperature fixed-point blackbody cells\", over the period from around summer 2014 to the final measurements made during January 2020. The report presents differences of the participant data from the KCRV values for both the radiation thermometer and HTFP measurements. Note: this interim report excludes the measurement data of VNIIM, Russia - see explanation at the end of Section 6. 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 CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"43 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survey of bidirectional transmittance distribution function measurement facilities by multilateral scale comparisons","authors":"Jinglin Fu, Alejandro Ferrero, Tatjana Quast, Michael Esslinger, Pablo Santafé-Gabarda, Néstor Tejedor, Joaquín Campos, Lou Gevaux, Gaël Obein, Robin Aschan, Farshid Manoocheri, Erkki Ikonen, Geiland Porrovecchio, Marek Šmíd, Ellie Molloy, Annette Koo, Søren A Jensen, Rafael Oser, Jan Audenaert, Youri Meuret, Stefan Källberg, Iryna Gozhyk, Tobias Kraus and Alfred Schirmacher","doi":"10.1088/1681-7575/ad3fbd","DOIUrl":"https://doi.org/10.1088/1681-7575/ad3fbd","url":null,"abstract":"In recent years, a growing demand for the capability of performing accurate measurements of the bidirectional transmittance distribution function (BTDF) has been observed in industry, research and development, and aerospace applications. However, there exists no calibration and measurement capabilities-entry for BTDF in the database of the Bureau International des Poids et Mesures and to date no BTDF comparison has been conducted between different national metrology institutes (NMIs) or designated institutes (DIs). As a first step to a possible future key comparison and to test the existing capabilities of determining this measurand, two interlaboratory comparisons were performed. In comparison one, five samples of three different types of optical transmissive diffusers were measured by five NMIs and one DI. By specific sample choice, the focus for this study lay more on orientation-dependent scatter properties. In comparison two, where one NMI, one DI, one university, and three industrial partners investigated their measurement capabilities, the dependence on the orientation was not assessed, but two additional samples of the same material and different thickness were measured. Results of the two comparisons are presented, giving a good overview of existing experimental solutions, and showing specific sample-related problems to be solved for improved future BTDF measurements.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"46 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The CIPM list ‘Recommended values of standard frequencies’: 2021 update","authors":"H S Margolis, G Panfilo, G Petit, C Oates, T Ido, S Bize","doi":"10.1088/1681-7575/ad3afc","DOIUrl":"https://doi.org/10.1088/1681-7575/ad3afc","url":null,"abstract":"This paper gives a detailed account of the analysis underpinning the 2021 update to the list of standard reference frequency values recommended by the International Committee for Weights and Measures. This update focused on a subset of atomic transitions that are secondary representations of the second (SRS) or considered as potential SRS. As in previous updates in 2015 and 2017, methods for analysing over-determined data sets were applied to make optimum use of the worldwide body of published clock comparison data. To ensure that these methods were robust, three independent calculations were performed using two different algorithms. The 2021 update differed from previous updates in taking detailed account of correlations among the input data, a step shown to be important in deriving unbiased frequency values and avoiding underestimation of their uncertainties. It also differed in the procedures used to assess input data and to assign uncertainties to the recommended frequency values, with previous practice being adapted to produce a fully consistent output data set consisting of frequency ratio values as well as absolute frequencies. These changes are significant in the context of an anticipated redefinition of the second in terms of an optical transition or transitions, since optical frequency ratio measurements will be critical for verifying the international consistency of optical clocks prior to the redefinition. In the meantime, the reduced uncertainties for optical SRS resulting from this analysis significantly increases the weight that secondary frequency standards based on these transitions can have in the steering of International Atomic Time.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"86 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}