Isotopic effects in the neon fixed point: uncertainty of the calibration data correction

Steur, P. P. M.; Pavese, Franco; Fellmuth, B.; Hermier, Y.; Hill, Kathryn; Kim, Jin Seog; Lipiński, L.; Nagao, Keisuke; Nakano, Tohru; Peruzzi, Andrea; Sparasci, F.; Szmyrka-Grzebyk, A.; Tamura, Osamu; Tew, Weston L.; Valkiers, S.; Geel, Jan Van

doi:10.1088/0026-1394/52/1/104

Cited by 12 publications

(17 citation statements)

References 13 publications

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“…Recently, the Technical Annex was expanded to include the case of neon as well. After extensive research on the effect of the isotopic composition on T tp−Ne [2][3][4][10][11][12][13][14][15][16], the Technical Annex now specifies a reference formula to correct for the isotope reference ratios. The difference in the measured T tp−Ne value from the value T 90 (Ne TP) = 24.5561 K as defined in the ITS-90 is…”

Section: Introductionmentioning

confidence: 99%

Triple-Point Temperature and the Isotopic Composition of Three Commercial Neon Gases

et al. 2015

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The triple-point temperature of neon, T tp−Ne , is known to have dependence on the isotopic composition. Recently, the Technical Annex for the International Temperature Scale of 1990 was updated to specify the method of correction for the isotopic reference ratio of neon. In this study, to confirm this correction in the Technical Annex independently, the effects of the isotopic composition of neon on T tp−Ne for three commercial neon gas sources were studied. For the measurement of the isotopic composition, a gas mass spectrometer was used to compare the sample gases with a reference neon gas whose isotopic composition was known with high precision by a gravimetric method. For the measurement of T tp−Ne , an open-cell type cryostat for the realization of low-temperature fixed points was used. The physical cell and the thermal environment around it remained very similar for all T tp−Ne measurements with the neon gases due to the nature of the open-cell type system. Therefore, the difference in T tp−Ne among different samples could be measured with a relatively low uncertainty, canceling many systematic effects that are common to all measurements. Our result was consistent with the correction in the Technical Annex. Furthermore, because one of the commercial neon gases was the bottle that was used for KRISS measurements in the international comparison CCT-K2, it is now possible to correct the measurement for the reference isotopic ratio and compare it with other measurements for which isotopic composition data are available.

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Section: Introductionmentioning

confidence: 99%

Triple-Point Temperature and the Isotopic Composition of Three Commercial Neon Gases

et al. 2015

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“…All the outcomes of the Project are now published, as far as the thermal studies are concerned, including evidence of perfect ideality of the isotopic mixture up to the composition of natural neon. As a final outcome, the Bureau International des Poids et Mesures (BIPM) endorsed, by formal inclusion in the Mise en Pratique (MeP) of the kelvin, the proposed equation for the correction of the measured neon triple point temperature for the actual isotopic composition of the sample used, when known [8,10,16]. The main object of the Project was the determination of isotopic effects on the neon triple point temperature.…”

Section: Summary Of the Inter-comparison Of Analytical Assaysmentioning

confidence: 99%

“…In comprehensive studies lasting from 2003 to 2014 the effect of isotopic composition on the triple point temperature was tested on neon of different isotopic compositions obtained from commercial sources [http://www.euramet.org/research-innovation/search-research-projects/details/?eurametCtcp_project_ show[project]=648(EUROMET Project 770: Determination of an accurate T tp vs. x(isotopic) relationship for neon)]. These studies involved 10 National Metrology Institutes (NMIs) and three chemical-assay laboratories [1][2][3][4][5][6][7][8][9][10][11]. The relevance of the isotopic effects in thermometry has already been discussed in depth in [8] and references therein.…”

Section: Introductionmentioning

confidence: 99%

An inter-comparison of isotopic composition of neon via chemical assays and thermal analyses (IUPAC Technical Report)

Steur

Yang

Kim

et al. 2019

Pure and Applied Chemistry

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In 2003–2014, a study on the effect of isotopic composition on the triple point temperature of neon was conducted under the framework of a Project involving laboratories from 11 countries. Natural neon from commercial sources of different isotopic composition, high-purity 20Ne and 22Ne isotopes, and certified artificial isotopic mixtures were used. The thermometric studies comprised: a) a total of 131 analytical assays from 3 laboratories on the isotopic composition of samples taken from 31 different bottles of neon with chemical gas purity 99.99 mol % to 99.9995+ mol %, including chemical impurities for some samples, with up to 12 assays per sample; b) multi-laboratory thermal analyses, with accuracies ranging up to better than 50 μK (k≈2), on 39 samples, almost all permanently sealed in metal cells, for the determination of the liquidus-point temperature of the triple point as a function of isotopic composition. The thermometric studies also constitute an international inter-comparison of thermal and analytical assays on the isotopic composition—and occasionally of the chemical impurities—of neon. These tests are critically needed for top-accuracy thermometry. The main results of the inter-comparison of the various chemical assays, and of the comparisons between the assays and the results of thermal analyses, are reported. They show discrepancies in x(20,21,22Ne), especially for x(22Ne), in ‘natural’ neon, for the same gas bottle, equivalent to an uncertainty of up to 165 μK (k = 1) in the triple point temperature, as measured by all testing laboratories, and of about 100 μK (k = 1) as measured from a single testing laboratory. This is an unsatisfactory situation for thermometry, since it is difficult to obtain a reliable and accurate isotopic assay for neon, thus limiting the accuracy of the realisation of the neon triple point temperature as a ITS-90 reference point to well above 50 μK. However, it also discloses a strong limitation in the relevant analytical chemistry.

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“…Isotopic studies were undertaken, initially on e-H 2 (HD in H 2 ) [5,6] and H 2 O (D 2 and 18 O 2 ) [7][8][9][10], and later also on Ne [4,[11][12][13][14][15].…”

Section: State Of the Artmentioning

confidence: 99%

“…The choice of the NRC F15 sample seems the most obvious, since NRC was the pilot in all K2.x comparisons; (iii) for NRC's last reference cell, Cu-M-1, the isotopiceffect difference to One could then compute the T meas,ac by simply adding to DT meas the DT x obtained from the ITS-90 Technical Annex of [31], and then compute the weighted mean from the latter set, for both sets #1 and #2: dT meas,ac = T meas,corr -T(KCRV ac ). The isotopic corrections are reported in Table 3 in the column "Isotopic DT", For the isotopic composition of the samples, see [13][14][15]. The KCRV ac are reported in Table 3: T KCRVac = 24.566 47 1 K for thermometers #1, and T KCRVac = 24.566 55 8 K for thermometers #2, different, as expected, from the KCRVs before correction: notice that these values correspond to the values in item (viii) above well within the uncertainties.…”

Section: Main Comparison (Cct-k2)mentioning

confidence: 99%

The ITS-90 after definition of neon isotopic reference composition: extent of the isotopic effect tested on previous inter-comparison results

Pavese¹,

Szmyrka-Grzebyk²,

Steur

2017

Int. J. Metrol. Qual. Eng.

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Abstract. Starting from the end of the past century, the importance has been recognised of the effect of isotopic composition on some of the temperature fixed points for the most accurate realisations of the ITS-90. In the original definition of the latter, dating back to 1990, only a generic reference was made to "natural" composition of the substances used for the realisation of the fixed points, except for helium. The definition of a reference isotopic composition for three fixed points, e-H 2 , Ne and H 2 O, while eliminating the non-uniqueness of the Scale in this respect, induced detectable differences in the present and future realisations of the Scale, at the highest accuracy level, with respect to the previous realisations, when they affected the results of past MRA key comparisons, namely the CCT K1 (and K1.1) and CCT K2 (and K2.1-K2.5) and the related regional and supplementary ones. The paper provides evidence of the extent of this effect by using the results of the relevant key comparisons for neon archived in the BIPM KCDB, and of other comparisons existing in the literature (1979-1984, 2007-2012 and 2009-2010 sealed cell comparisons), and discusses the meaning and the outcomes of this evaluation.

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Isotopic effects in the neon fixed point: uncertainty of the calibration data correction

Cited by 12 publications

References 13 publications

Triple-Point Temperature and the Isotopic Composition of Three Commercial Neon Gases

Triple-Point Temperature and the Isotopic Composition of Three Commercial Neon Gases

An inter-comparison of isotopic composition of neon via chemical assays and thermal analyses (IUPAC Technical Report)

The ITS-90 after definition of neon isotopic reference composition: extent of the isotopic effect tested on previous inter-comparison results

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