Pub Date : 2023-11-16DOI: 10.1088/0026-1394/60/1a/06023
R Nylund, L A de Prez, P O Hetland, C E Andersen, P Aviles, C G Mulas, Z Msimang, L Czap, L Persson
Main textA key comparison of the standards for air kerma and absorbed dose to water of seven participating laboratories was carried out in the 60Co radiation beam, therapy level, during October 2021 to November 2022. Six of the participating laboratories are secondary standards laboratories (SSM, DSA, STUK, DTU, CIEMAT, and IAEA) and VSL is a primary standards laboratory and acted as a linking laboratory to respective BIPM key comparisons. The comparison results are published in the BIPM key comparison database (KCDB) under the reference EURAMET.RI(I)-K1.3 and EURAMET.RI(I)-K4.3. The comparison was made indirectly using three thimble-type ionization chambers as transfer instruments. The results are analyzed 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).
{"title":"Key comparisons of air kerma and absorbed dose to water standards in 60Co radiation beam (EURAMET.RI(I)-K1.3 and EURAMET.RI(I)-K4.3)","authors":"R Nylund, L A de Prez, P O Hetland, C E Andersen, P Aviles, C G Mulas, Z Msimang, L Czap, L Persson","doi":"10.1088/0026-1394/60/1a/06023","DOIUrl":"https://doi.org/10.1088/0026-1394/60/1a/06023","url":null,"abstract":"<title>Main text</title>A key comparison of the standards for air kerma and absorbed dose to water of seven participating laboratories was carried out in the <sup>60</sup>Co radiation beam, therapy level, during October 2021 to November 2022. Six of the participating laboratories are secondary standards laboratories (SSM, DSA, STUK, DTU, CIEMAT, and IAEA) and VSL is a primary standards laboratory and acted as a linking laboratory to respective BIPM key comparisons. The comparison results are published in the BIPM key comparison database (KCDB) under the reference EURAMET.RI(I)-K1.3 and EURAMET.RI(I)-K4.3. The comparison was made indirectly using three thimble-type ionization chambers as transfer instruments. The results are analyzed 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 <ext-link xlink:href=\"https://www.bipm.org/documents/d/guest/euramet-ri-i-k1-3_euramet-ri-i-k4-3\" xlink:type=\"simple\">Final Report</ext-link>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <ext-link xlink:href=\"https://www.bipm.org/kcdb/\" xlink:type=\"simple\">https://www.bipm.org/kcdb/</ext-link>.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).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"14 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138692858","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}
Pub Date : 2023-11-14DOI: 10.1088/1681-7575/ad0c9f
Stefaan Pommé, Heiko Stroh, Timotheos Altzitzoglou, Jan Paepen, Raf Van Ammel, Maria Marouli, Leen Verheyen, Michael Unterweger, Ryan Fitzgerald, Denis Bergeron, L Pibida, Ole J. Naehle, Karsten Kossert, Natasha Ramirez, Emma Bendall, Andrew Fenwick, Kelley Ferreira, John Keightley, Mihaela Baker, Sean Collins, Carine Michotte, Sammy Courte, Romain Maximilien Coulon, Tim Jackson, Freda Van Wyngaardt, Aldo Fazio, Pierino De Felice, Branko Vodenik, M Korun, Frederic Juget, Claude J Bailat, Youcef Nedjadi, Francois O Bochud, Thierry Buchillier, Timothy Roy, Raphael Galea, Ivan Kajan, Milton van Rooy, Paul McGinnity, Ivana Tucakovic, Iolanda Osvath, Krzysztof Pelczar
Abstract 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.
{"title":"Ambient humidity, the overlooked influencer of radioactivity measurements","authors":"Stefaan Pommé, Heiko Stroh, Timotheos Altzitzoglou, Jan Paepen, Raf Van Ammel, Maria Marouli, Leen Verheyen, Michael Unterweger, Ryan Fitzgerald, Denis Bergeron, L Pibida, Ole J. Naehle, Karsten Kossert, Natasha Ramirez, Emma Bendall, Andrew Fenwick, Kelley Ferreira, John Keightley, Mihaela Baker, Sean Collins, Carine Michotte, Sammy Courte, Romain Maximilien Coulon, Tim Jackson, Freda Van Wyngaardt, Aldo Fazio, Pierino De Felice, Branko Vodenik, M Korun, Frederic Juget, Claude J Bailat, Youcef Nedjadi, Francois O Bochud, Thierry Buchillier, Timothy Roy, Raphael Galea, Ivan Kajan, Milton van Rooy, Paul McGinnity, Ivana Tucakovic, Iolanda Osvath, Krzysztof Pelczar","doi":"10.1088/1681-7575/ad0c9f","DOIUrl":"https://doi.org/10.1088/1681-7575/ad0c9f","url":null,"abstract":"Abstract 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.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"20 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134953765","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}
Pub Date : 2023-11-14DOI: 10.1088/1681-7575/ad0c9e
Kinza Maham, Vili Kosonen, Juha Peltoniemi, Petri Kärhä, Erkki Ikonen
Abstract When studying the results of the key comparisons of spectral quantities, it appears that in many cases participants’ results systematically deviate from the key comparison reference value over a limited spectral range. We carried out spectral analysis of such deviations in seven key comparisons of optical radiometry. The results reveal an approximate outcome that, on the average, each harmonic amplitude is inversely proportional to the order of the harmonic in all studied key comparisons. This new finding gives important information on the characteristics of spectral correlations. The result can be used in the uncertainty evaluation of spectral integrals, where the effect of unknown spectral correlations has earlier been challenging to assess quantitatively.
{"title":"Spectral analysis of deviations from key comparison reference values","authors":"Kinza Maham, Vili Kosonen, Juha Peltoniemi, Petri Kärhä, Erkki Ikonen","doi":"10.1088/1681-7575/ad0c9e","DOIUrl":"https://doi.org/10.1088/1681-7575/ad0c9e","url":null,"abstract":"Abstract When studying the results of the key comparisons of spectral quantities, it appears that in many cases participants’ results systematically deviate from the key comparison reference value over a limited spectral range. We carried out spectral analysis of such deviations in seven key comparisons of optical radiometry. The results reveal an approximate outcome that, on the average, each harmonic amplitude is inversely proportional to the order of the harmonic in all studied key comparisons. This new finding gives important information on the characteristics of spectral correlations. The result can be used in the uncertainty evaluation of spectral integrals, where the effect of unknown spectral correlations has earlier been challenging to assess quantitatively.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"17 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134953580","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}
Pub Date : 2023-11-13DOI: 10.1088/1681-7575/ad023e
Xin-Liang Wang, Jun Ruan, Dan-Dan Liu, Yong Guan, Jun-Ru Shi, Fan Yang, Yang Bai, Hui Zhang, Si-Chen Fan, Wen-Jun Wu, Shu-Hong Zhao, Shou-Gang Zhang
Abstract Caesium fountain primary frequency standards have been used to realize the definition of the second in the International System of units for more than two decades. This paper reports the structure and uncertainty evaluation of the NTSC-CsF2, developed by National Time Service Center (NTSC), Chinese Academy of Sciences. The short-term stability at high atomic density is 2.1 × 10 −13 at 1 s of averaging time. The fractional combined type B uncertainty is evaluated at 4.3 × 10 −16 . A frequency comparison has been conducted between NTSC-CsF2 and the SI second through a Global Navigation Satellite System link for eight months whose results show a fractional frequency difference of 4.2(5.2) × 10 −16 . With a reduced chi-square of 0.8, NTSC-CsF2 is found to be consistent with that of the other fountains within the uncertainty.
{"title":"First evaluation of the Primary Frequency Standard NTSC-CsF2","authors":"Xin-Liang Wang, Jun Ruan, Dan-Dan Liu, Yong Guan, Jun-Ru Shi, Fan Yang, Yang Bai, Hui Zhang, Si-Chen Fan, Wen-Jun Wu, Shu-Hong Zhao, Shou-Gang Zhang","doi":"10.1088/1681-7575/ad023e","DOIUrl":"https://doi.org/10.1088/1681-7575/ad023e","url":null,"abstract":"Abstract Caesium fountain primary frequency standards have been used to realize the definition of the second in the International System of units for more than two decades. This paper reports the structure and uncertainty evaluation of the NTSC-CsF2, developed by National Time Service Center (NTSC), Chinese Academy of Sciences. The short-term stability at high atomic density is 2.1 × 10 −13 at 1 s of averaging time. The fractional combined type B uncertainty is evaluated at 4.3 × 10 −16 . A frequency comparison has been conducted between NTSC-CsF2 and the SI second through a Global Navigation Satellite System link for eight months whose results show a fractional frequency difference of 4.2(5.2) × 10 −16 . With a reduced chi-square of 0.8, NTSC-CsF2 is found to be consistent with that of the other fountains within the uncertainty.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"7 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134992703","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}
Pub Date : 2023-11-10DOI: 10.1088/1681-7575/ad088b
Thomas Parker, Roger Brown, Jeffrey Sherman
Abstract Residual time delays in time transfer systems such as two-way satellite time and frequency transfer (TWSTFT), or GPS carrier phase (GPSCP) change over time. A double difference such as TWSTFT—GPSCP provides information on the changes in the relative time delays of the two systems. These changes are referred to as aging or time dispersion. A first difference statistic, RMS time interval error, TIE RMS , provides the RMS time dispersion. The time deviation statistic (TDEV) or a variation on the Allan deviation (ADEV), referred to here as ADEVS, provide information on the nature of the random fluctuations in aging. This paper describes analytical and Monte Carlo techniques used to estimate the aging (time dispersion) from TDEV or ADEVS statistics, and finds that the aging can be more than a factor of four larger than TDEV or ADEVS. The use of ADEVS is recommended over TDEV since it is sensitive to time drift.
{"title":"Statistics for quantifying aging in time transfer system delays","authors":"Thomas Parker, Roger Brown, Jeffrey Sherman","doi":"10.1088/1681-7575/ad088b","DOIUrl":"https://doi.org/10.1088/1681-7575/ad088b","url":null,"abstract":"Abstract Residual time delays in time transfer systems such as two-way satellite time and frequency transfer (TWSTFT), or GPS carrier phase (GPSCP) change over time. A double difference such as TWSTFT—GPSCP provides information on the changes in the relative time delays of the two systems. These changes are referred to as aging or time dispersion. A first difference statistic, RMS time interval error, TIE RMS , provides the RMS time dispersion. The time deviation statistic (TDEV) or a variation on the Allan deviation (ADEV), referred to here as ADEVS, provide information on the nature of the random fluctuations in aging. This paper describes analytical and Monte Carlo techniques used to estimate the aging (time dispersion) from TDEV or ADEVS statistics, and finds that the aging can be more than a factor of four larger than TDEV or ADEVS. The use of ADEVS is recommended over TDEV since it is sensitive to time drift.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"66 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135087364","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}
Pub Date : 2023-11-08DOI: 10.1088/1681-7575/ad0abe
Joele Viallon, Christopher W Meyer, Philippe Moussay, J W Schmidt, Stephen E Maxwell, Fredrik Arrhen, Robert Wielgosz
Abstract The design, performance characteristics and validation of a next generation reference facility for CO 2 in air standards based on manometry is presented. Novel attributes of the facility include automated operation, avoidance of significant pressure corrections for measurements on extracted CO 2 , fully characterized trapping efficiencies, and reduced measurement uncertainty. 
Improvements in system performance have been achieved using specific materials, notably Silconert®-treated stainless-steel , providing increased mechanical stability whilst minimizing carbon dioxide adsorption on surfaces, and avoiding use of elastomer O-rings, which would lead to losses of CO 2 . Full automation of the cryogenic extraction process of CO 2 from air has been achieved, avoiding any manual intervention within the temperature stabilized section of the facility, and allowed full characterization and correction for trapping efficiencies and trace water measurement.
The facility has been validated across the CO 2 in air amount fraction range of (380 to 800) µmol mol −1 using standards with values traceable to the reference value of the CCQM−K120 (2018) comparison. It was demonstrated to operate with a standard measurement uncertainty of 0.09 µmol mol −1 at 400 µmol mol −1 . The automation allows five measurement results per day to be produced with a typical standard deviation of the mean at or below 0.02 µmol mol −1 .
The facility will be used as a stable reference in the future ongoing BIPM.QM−K2 comparison, to compare consistency of amount fraction values in different CO 2 in air standards. The CO 2 amount fraction in two ensembles of nine BIPM standards covering the same range will also be measured with the facility to provide their SI-traceable values, and further monitored on a longer time scale. Each ensemble will constitute a CO 2 in air scale for comparison with other available scales such as WMO.CO2.X2019 through the BIPM.QM−K5 comparison.
{"title":"A high accuracy reference facility for ongoing comparisons of CO<sub>2</sub> in air standards","authors":"Joele Viallon, Christopher W Meyer, Philippe Moussay, J W Schmidt, Stephen E Maxwell, Fredrik Arrhen, Robert Wielgosz","doi":"10.1088/1681-7575/ad0abe","DOIUrl":"https://doi.org/10.1088/1681-7575/ad0abe","url":null,"abstract":"Abstract The design, performance characteristics and validation of a next generation reference facility for CO 2 in air standards based on manometry is presented. Novel attributes of the facility include automated operation, avoidance of significant pressure corrections for measurements on extracted CO 2 , fully characterized trapping efficiencies, and reduced measurement uncertainty. &#xD;Improvements in system performance have been achieved using specific materials, notably Silconert®-treated stainless-steel , providing increased mechanical stability whilst minimizing carbon dioxide adsorption on surfaces, and avoiding use of elastomer O-rings, which would lead to losses of CO 2 . Full automation of the cryogenic extraction process of CO 2 from air has been achieved, avoiding any manual intervention within the temperature stabilized section of the facility, and allowed full characterization and correction for trapping efficiencies and trace water measurement.&#xD;The facility has been validated across the CO 2 in air amount fraction range of (380 to 800) µmol mol −1 using standards with values traceable to the reference value of the CCQM−K120 (2018) comparison. It was demonstrated to operate with a standard measurement uncertainty of 0.09 µmol mol −1 at 400 µmol mol −1 . The automation allows five measurement results per day to be produced with a typical standard deviation of the mean at or below 0.02 µmol mol −1 .&#xD;The facility will be used as a stable reference in the future ongoing BIPM.QM−K2 comparison, to compare consistency of amount fraction values in different CO 2 in air standards. The CO 2 amount fraction in two ensembles of nine BIPM standards covering the same range will also be measured with the facility to provide their SI-traceable values, and further monitored on a longer time scale. Each ensemble will constitute a CO 2 in air scale for comparison with other available scales such as WMO.CO2.X2019 through the BIPM.QM−K5 comparison.&#xD;","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":" 23","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135341420","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}
Pub Date : 2023-11-07DOI: 10.1088/1681-7575/ad0a35
Allan H Harvey
Abstract Constant-volume gas thermometry data published in 1989 for the difference between the thermodynamic temperature and the International Practical Temperature Scale of 1968 are corrected in two ways. A refined estimate of the thermal expansivity of the material of the gas bulb, published in 1990, increases the thermodynamic temperature by amounts on the order of 1 mK to 3 mK. Better knowledge of the nonideality of helium gas reduces the uncertainty of the nonideality correction to near zero and decreases the thermodynamic temperature by amounts on the order of 0.1 mK to 0.5 mK. The net effect is a small increase in the thermodynamic temperature derived from the 1989 experiments. The magnitude of this increase is approximately 2 mK at 505 K, increasing to 3 mK at temperatures near 700 K, and then diminishing to near 0.5 mK at the highest temperature of the measurements (933 K). These corrections are smaller than the uncertainty of the experiments, but may be of significance for future recommendations for the relationship between the thermodynamic temperature and the consensus scale in this temperature range.
{"title":"Small Corrections to 1989 NIST Constant-Volume Gas Thermometry Data","authors":"Allan H Harvey","doi":"10.1088/1681-7575/ad0a35","DOIUrl":"https://doi.org/10.1088/1681-7575/ad0a35","url":null,"abstract":"Abstract Constant-volume gas thermometry data published in 1989 for the difference between the thermodynamic temperature and the International Practical Temperature Scale of 1968 are corrected in two ways. A refined estimate of the thermal expansivity of the material of the gas bulb, published in 1990, increases the thermodynamic temperature by amounts on the order of 1 mK to 3 mK. Better knowledge of the nonideality of helium gas reduces the uncertainty of the nonideality correction to near zero and decreases the thermodynamic temperature by amounts on the order of 0.1 mK to 0.5 mK. The net effect is a small increase in the thermodynamic temperature derived from the 1989 experiments. The magnitude of this increase is approximately 2 mK at 505 K, increasing to 3 mK at temperatures near 700 K, and then diminishing to near 0.5 mK at the highest temperature of the measurements (933 K). These corrections are smaller than the uncertainty of the experiments, but may be of significance for future recommendations for the relationship between the thermodynamic temperature and the consensus scale in this temperature range.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"317 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135474911","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}
Pub Date : 2023-11-07DOI: 10.1088/1681-7575/ad0a36
Romain Maximilien Coulon, Carine Michotte, Vincent Gressier
Abstract In support of the CIPM MRA, the reference system in radionuclide metrology (SIR) is a unique experimental facility that has been able to provide continuous key comparison results for 72 radionuclides for 46 years. These measurement data are now available in a machine-readable format, which allows statistical analysis of these measurement results to be performed efficiently. Such a meta-analysis was conducted to verify whether or not the accumulated data confirmed the bold assumption made in the 1970s of the long-term robustness of the system over decades of operation. It was notably assumed that variation in the properties of the standard solution to be measured or the choice of the 226 Ra reference source would have no impact on the measurement.
For the majority of radionuclides measured by the SIR, the non-parametric significance tests of the null hypothesis carried out in this study gave no evidence, at the 95 % confidence level, that the above statement should be reconsidered. However, this meta-analysis revealed a significant impact of solution density in the case of 109 Cd, corroborating previous observations made in the case of 241 Am where the robustness of an ionization chamber with respect to the density variation of the solution does not appear to be perfect.
The extension of the SIR by a liquid scintillation system is under development. It will improve the robustness of international comparison results for those borderline cases where radionuclides emit only low-energy x-rays or gamma rays (< 100 keV).
{"title":"Evaluation of long-term robustness of the International System of Reference (SIR) used in radionuclide metrology based on the meta-analysis of its machine-readable database","authors":"Romain Maximilien Coulon, Carine Michotte, Vincent Gressier","doi":"10.1088/1681-7575/ad0a36","DOIUrl":"https://doi.org/10.1088/1681-7575/ad0a36","url":null,"abstract":"Abstract In support of the CIPM MRA, the reference system in radionuclide metrology (SIR) is a unique experimental facility that has been able to provide continuous key comparison results for 72 radionuclides for 46 years. These measurement data are now available in a machine-readable format, which allows statistical analysis of these measurement results to be performed efficiently. Such a meta-analysis was conducted to verify whether or not the accumulated data confirmed the bold assumption made in the 1970s of the long-term robustness of the system over decades of operation. It was notably assumed that variation in the properties of the standard solution to be measured or the choice of the 226 Ra reference source would have no impact on the measurement.&#xD;For the majority of radionuclides measured by the SIR, the non-parametric significance tests of the null hypothesis carried out in this study gave no evidence, at the 95 % confidence level, that the above statement should be reconsidered. However, this meta-analysis revealed a significant impact of solution density in the case of 109 Cd, corroborating previous observations made in the case of 241 Am where the robustness of an ionization chamber with respect to the density variation of the solution does not appear to be perfect.&#xD;The extension of the SIR by a liquid scintillation system is under development. It will improve the robustness of international comparison results for those borderline cases where radionuclides emit only low-energy x-rays or gamma rays (< 100 keV).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"8 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135480306","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}
Abstract We present a new approach to report, in the section 4 of International Bureau of Weights and Measures Circular T, daily values of the offset between Coordinated Universal Time (UTC) and the predictions of UTC broadcast by the Global Navigation Satellite Systems (GNSS), this quantity we name bUTC GNSS . In this approach, the determination of UTC-bUTC GNSS is based on data collected by several multi-GNSS stations in selected time laboratories worldwide. Test computations over a 7-month period from July 2022 to January 2023 show that the offset between UTC and bUTC GNSS was between 30 and 50 ns for GLONASS, between 5 and 20 ns for BeiDou, and between −5 and +5 ns for GPS and Galileo. We derive the uncertainty on the reported values, which is 4.1 ns for BeiDou and GPS, 3.7 ns for Galileo and 6.6 ns for GLONASS and show that, over the test period, the reported values of UTC-bUTC GNSS and the solutions obtained from each multi-GNSS station are all consistent within the 1-sigma uncertainties.
摘要:我们提出了一种新的方法，在国际度量衡局(International Bureau of Weights and Measures Circular T)第4节中，报告协调世界时(UTC)与全球导航卫星系统(GNSS)广播的UTC预测之间的每日偏移值，我们将此量称为bUTC GNSS。在这种方法中，UTC-bUTC GNSS的确定基于全球选定时间实验室的多个多GNSS站收集的数据。从2022年7月到2023年1月的7个月的测试计算表明，GLONASS的UTC和bUTC GNSS之间的偏移量在30到50纳秒之间，北斗的偏移量在5到20纳秒之间，GPS和伽利略的偏移量在- 5到+5纳秒之间。我们推导了报告值的不确定性，北斗和GPS的不确定性为4.1 ns，伽利略的不确定性为3.7 ns, GLONASS的不确定性为6.6 ns，并表明在测试期间，UTC-bUTC GNSS的报告值与每个多GNSS站获得的解在1 σ不确定性范围内一致。
{"title":"Monitoring of the offset between UTC and its prediction broadcast by the GNSS","authors":"Pascale Defraigne, Elisa Pinat, Gerard Petit, Frédéric Meynadier","doi":"10.1088/1681-7575/ad0562","DOIUrl":"https://doi.org/10.1088/1681-7575/ad0562","url":null,"abstract":"Abstract We present a new approach to report, in the section 4 of International Bureau of Weights and Measures Circular T, daily values of the offset between Coordinated Universal Time (UTC) and the predictions of UTC broadcast by the Global Navigation Satellite Systems (GNSS), this quantity we name bUTC GNSS . In this approach, the determination of UTC-bUTC GNSS is based on data collected by several multi-GNSS stations in selected time laboratories worldwide. Test computations over a 7-month period from July 2022 to January 2023 show that the offset between UTC and bUTC GNSS was between 30 and 50 ns for GLONASS, between 5 and 20 ns for BeiDou, and between −5 and +5 ns for GPS and Galileo. We derive the uncertainty on the reported values, which is 4.1 ns for BeiDou and GPS, 3.7 ns for Galileo and 6.6 ns for GLONASS and show that, over the test period, the reported values of UTC-bUTC GNSS and the solutions obtained from each multi-GNSS station are all consistent within the 1-sigma uncertainties.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"4 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135585035","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}
Pub Date : 2023-10-31DOI: 10.1088/1681-7575/ad02a0
Yiwei Wu, Siran Liu
Abstract The Bureau International des Poids et Mesures uses the ALGOS algorithm to generate the Echelle Atomique Libre. The original and new ALGOS weighting algorithms employ two different statistics to calculate the weights, resulting in different experimental phenomena. These two statistics are believed to be the keys to analyzing these experimental phenomena, because the statistical characteristics (e.g. the mathematical expectations and variances) of the statistics completely determine the statistical characteristics of the weights, and subsequently the experimental phenomena. The core work conducted in this study is to derive the analytical expressions of the mathematical expectations of these two statistics under ideal conditions and to validate them empirically. This paper provides a theoretical analysis of these expressions and discusses the relationships between them and the mathematical expectations of the Allan variances. These expressions theoretically reveal the reasons behind the experimental phenomena, especially why hydrogen masers are assigned lower weights in the original ALGOS weighting algorithm but higher weights in the new one. According to the derivation process, these analytical expressions are universally applicable and can also be applied to time-keeping laboratories. In the future, this work can be extended to determine the theoretical statistic and weight performances of different types of frequency standards quantitatively for time-keeping laboratories under both ideal and non-ideal conditions, providing a theoretical basis for improving the design of ensemble time scale algorithms. In the appendix, a method of obtaining the experimental variances and probability density functions (PDFs) of these two statistics is additionally proposed. The two-sample Kolmogorov–Smirnov test is presented to compare the experimental and theoretical PDFs of an example.
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