| Zugriffsnummer | 16231 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | State-of-the-art level of accuracy achieved by realising low-temperature fixed points of the ITS-90 using sealed triple-point cells |
| Autor(in); Institution |
Fellmuth, Bernd; 7.32, Tieftemperaturmetrologie, PTB-Berlin
|
| Quelle/Jahr | Spectrum of metrology: from the state-of-the-art to the everyday : NCSL International annual workshop and symposium, Tampa, [August 17 - 21, 2003] ; conference proceedings 2003:(2003) |
| Availability | [CD-ROM] ; file name: 5E-2.pdf |
| ISBN | 1-584-64041-3 |
| Verlag | Boulder, Colo.: NCSL International |
| Konferenzangaben | National Conference of Standards Laboratories (NCSL) International Annual Workshop and Symposium, Tampa, Florida, 17-21, September, 2003, USA |
| Zusammenfassung | Below 273.16 K, the ITS-90 has eight defining fixed points. The realisation of four of them causes special problems because they are the triple points of cryogenic gases. In particular their very low thermal conductivity and small heat of fusion require using special methods: the melting curves have to be measured under nearly isothermal conditions. Temperature and shape of the observed melting curves depend strongly on the properties of the fixed-point samples. Furthermore, they are influenced by static and dynamic temperature-measurement errors. The state-of-art level of accuracy of realisations of the four triple points is evaluated on the basis of models describing the effects, which influence the melting curves, estimates of uncertainty components considering the properties of the substances and results of international intercomparisons of sealed cells containing permanently the fixed-point samples. The cells are quite different with respect to design, age, gas source and filling technology. This enables to investigate the different effects in detail. |
Zitierung
Fellmuth, B. (2003). State-of-the-art level of accuracy achieved by realising low-temperature fixed points of the ITS-90 using sealed triple-point cells. National Conference of Standards Laboratories (NCSL) International Annual Workshop and Symposium, Tampa, Florida, 17-21, September, 2003, USA.