Correction of the gas-thermometry scale of the VNIIFTRI in the range 2,5 K to 308 K

Abstract

New measurements of the thermal expansion of the copper used to manufacture the VNIIFTRI gas thermometer were performed and the temperature scale was corrected. The deviations of recalculated (gas) scale from the IPTS-68 scale and from the ITS-90 scale in the range 13 K to 308 K were found.

Progress towards the determination of thermodynamic temperature with ultra-low uncertainty

“…Particularly, the mutual consistency of various AGT data at T Ga is indeed striking, considering that these data were obtained with rather different, weakly correlated experiments [52], and motivates the further development of AGT at a higher temperature range. that the magnitude of the differences (T − T 90 ) have a smaller (less negative) magnitude than previously determined by AGT [13,17], in slightly better agreement with the CVGT data of Kemp et al [53] than with those of Astrov et al [54]. Most importantly, the outstanding progress achieved by the AGT method during the last few years is well illustrated by the visual comparison of the uncertainty of the WG4 interpolation (shaded area in figure 4) with the much smaller uncertainty associated with the dense NPL dataset.…”

Present Estimates of the Differences Between Thermodynamic Temperatures and the ITS-90

“…Results from acoustic gas thermometry (AGT) [10,11,15] indicate significant deviations of the ITS-90 from thermodynamic temperatures in the range below 273 K, with absolute values of almost 10 mK at 150 K. These values seem to be broadly consistent with (revised) results from Astrov's [8] CVGT. Two other CVGT experiments in the range (Steur [5], up to 100 K and Kemp [4], up to 287 K), together with the original Astrov [30] CVGT and Quinn and Martin's [24] total radiation thermometry, constituted the main ingredients for the construction of the ITS-90.…”

“…WG4 examined several effects that could have contributed to the difference. Astrov et al [8] Guildner & Edsinger [6] Edsinger & Schooley [7] Kemp et al [4] Quinn et al [24] Moldover et al [11] Strouse et al [13] Ewing & Trusler [10] Benedetto et al [14] Pitre et al [15] Ripple et al [12] (T68 -T90)…”

“…It was agreed to exclude the Quinn and Martin [24] total radiation measurements and the gas thermometry measurements of Guildner and Edsinger [6] from the averaging procedure as explained above, while those of Edsinger and Schooley [7] are retained. The gas thermometry results of Kemp, Steur, and Astrov [4,5,8] are retained for the averaging, but with recalculated uncertainties. The relative radiation thermometry of Fischer and Jung [16] at the Al, Ag, and Au points and of various other sources at the Cu point [23] are included to benefit from their low uncertainties.…”

“…The acoustic measurements denoted by blue or brown symbols can be seen in more detail in Fig. 2 Guildner & Edsinger [6] Astrov et al [8] Kemp et al [4] Quinn et al [24] Fox et al [17] Stock et al [18] Taubert et al [19] Noulkhow et al [20] Goebel et al [22] Yoon et al [21] Fischer & Jung [16] Moldover et al [11] Ewing & Trusler [10] Strouse et al [13] Ripple et al [12] Benedetto et al [14] Pitre et al [15] Edler et al [25] Labenski et al [26] various [23] (T68 -T90) ITS-90, +u (k = 1) ITS-90, -u (k = 1) mean smooth function …”