Tew, W.
, Egan, P.
and Gillis, K.
(2026),
A prospectus on direct traceability to the kelvin for point-of-use applications, Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences, [online], https://doi.org/10.1098/rsta.2024.0462, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959972
(Accessed March 28, 2026)
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A prospectus on direct traceability to the kelvin for point-of-use applications
Published
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Abstract
The revised definition of the kelvin has created new interest in alternative paths of traceability to the SI. In particular, development of methods for the direct realization of the kelvin are ongoing, establishing traceability without the need to go through the international-consensus temperature scale, the ITS-90. These direct realization methods are in contrast to the ITS-90 and the measurement infrastructure of reference materials and artifact thermometer calibration chains. This infrastructure has been built up over a century or more of industrialization and scientific progress, and while very robust, is not well suited to address the requirements of the most demanding of application environments. We examine how direct traceability to the kelvin can be applied to address those applications and assess the relative practical merits of various direct realization approaches. Primary thermometry methods are surveyed from the standpoint of achievable uncertainties over the range 4 K to 1800 K with examples of practical direct-realization technologies. This assessment points to a narrow application space of long-term missions, or those occurring in remote or hazardous environments, as the most compelling cases for the direct realization approach. We examine two examples of special application environments where those performance advantages could be the best suited for point-of-use measurement.Citation
Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences
Volume
384
Pub Type
Journals
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Keywords
Temperature, Traceability, Measurement Technology, kelvin, Thermometry, Thermodynamic
Citation
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Created January 15, 2026, Updated March 27, 2026