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Title: Realizations of the ITS-90 below 24.5561 K at NMIJ/AIST

The International Temperature Scale of 1990 (ITS-90) down to its defined minimum temperature of 0.65 K has been realized at the National Metrology Institute of Japan (NMIJ), using a {sup 3}He vapor pressure thermometer (VPT) from 0.65 K to 3.2 K, a {sup 4}He VPT from 2.2 K to 4.2 K, an interpolating constant-volume gas thermometer (ICVGT) from 3 K to 24.5561 K and standard platinum resistance thermometers (SPRTs) above 13.8803 K. The scales realized by these different thermometers in the overlapped temperature ranges differ among each other. These differences, also known as the non-uniqueness of the ITS-90, are estimated and reported in this paper. The difference between the scales of the SPRTs and ICVGT has a maximum of about 0.6 mK at temperatures close to 15 K, though it is about half of the propagation of the calibration uncertainties of the SPRT at the fixed points. The difference between the vapor pressure scales of {sup 4}He and {sup 3}He shows temperature dependence, which is consistent with that reported previously and has a maximum of about 0.2 mK at temperatures close to 3.1 K. The differences between the ICVGT scales with different lowest calibration temperatures are also estimated. The differencemore » between the ICVGT scales with or without corrections for the aerostatic pressure head, the dead-space volume effect and the thermomolecular pressure difference has a maximum of about 0.17 mK.« less
Authors:
; ; ;  [1]
  1. National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology AIST Tsukuba Central-3, Umezono 1-1-1, Tsukuba, Ibaraki 305-8563 (Japan)
Publication Date:
OSTI Identifier:
22218011
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1552; Journal Issue: 1; Conference: 9. international temperature symposium, Los Angeles, CA (United States), 19-23 Mar 2012; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CALIBRATION; CORRECTIONS; ELECTRIC CONDUCTIVITY; HELIUM; HELIUM 3; HELIUM 4; PLATINUM; PRESSURE MEASUREMENT; SENSORS; TEMPERATURE DEPENDENCE; TEMPERATURE MEASUREMENT; THERMOMETERS; VAPOR PRESSURE