A new calorimeter for the simultaneous calibration of SPRTs and CSPRTs at the triple point of mercury

CCT-K2.4: NRC/INTiBS/LNE-Cnam trilateral comparison of capsule-type standard platinum resistance thermometers from 13.8 K to 273.16 K

“…To overcome the problem, LNE-Cnam built and characterized a new type of calorimeter for the calibration of both long-stem and capsule-type SPRTs at the mercury triple point. Measurements carried out with CSPRT 1041 in the new cell [9] are in agreement with the CCT-K2 measurements. This validates the hypothesis that the CCT-K2.4 measurements at the mercury triple point reported by LNE-Cnam were unreliable.…”

Comparison of ITS-90 realizations from 13 K to 273 K between LNE-CNAM and INRIM

“…W(T90) = R(T90) / R(273.16 K), where R are resistance values corrected for all the effects mentioned in Section 2. Both uMRA and ubest standard uncertainties are reported here directly in millikelvins with a coverage factor k = 1. dT/dW are the mean sensitivity values of the thermometer calculated at each fixed point from the W values, computed with the respective conversion software according to the deviation function (12) in [2], while dTij are the temperature differences between the two laboratories, computed as dTij = (dT/dW)•(Wi -Wj). Lastly, the degree of equivalence, d0.95, between the two NMIs is calculated on the basis of the expression [25]: Globally, ubest uncertainties are evaluated in the same way as uMRA.…”

“…In 2013, LNE-CNAM developed a calorimeter for the simultaneous calibration of long-stem and CSPRTs at the TP of Hg [12]. The difference with most traditional systems [11] is the capability to perform calorimetric realizations of the phase transition, as the apparatus is essentially an isothermal cryostat.…”

“…The Hg TP is realized in systems which differ widely in the two laboratories. INRIM employs cells immersed in a bath supplying continuous heating [11], while LNE-CNAM uses miniature cells in an isothermal cryostat [12], and realizes the phase transition on the basis of the calorimetric method [10]. The TPW is realized in the same way, with quartz sealed cells inside a temperature-controlled bath [13].…”

“…The first was calibrated at LNE-CNAM by comparison with RIRTs B115 (NIST calibration) and B188 (NPL calibration), while the second was calibrated at NPL.Reference thermometers are installed in the same cell assembly as the thermometers under calibration and the measurements are performed with the same cryocooler and at the same temperature excursion realized for the TPs measurements. In this way, the reference thermometers are measured also at the TP temperatures, allowing an in-situ check of the stability of their calibration.2.2.3 Triple point of Hg and associated apparatusIn 2013, LNE-CNAM developed a calorimeter for the simultaneous calibration of long-stem and CSPRTs at the TP of Hg[12]. The difference with most traditional systems[11] is the capability to perform calorimetric realizations of the phase transition, as the apparatus is essentially an isothermal cryostat.…”