High-accuracy realization of temperature fixed and reference points.

Area of Science:

• Metrology
• Thermodynamics
• Physical Chemistry

Background:

• International temperature measurements require accurate realization of reference points due to temperature's unique properties.
• The International Temperature Scales (ITS) define fixed points and interpolation instruments to cover the range from 1 mK to 1000 K.
• Diverse phase transitions, from classical to superconducting, are used to establish these temperature points.

Purpose of the Study:

• To review the central topic of uncertainty estimation in the realization of temperature reference points.
• To discuss a unified methodology for estimating uncertainties by considering physical effects influencing phase-transition temperatures.
• To summarize recommendations from the Consultative Committee for Thermometry and supplement with author experiences.

Main Methods:

• Focus on estimating the magnitude of physical effects influencing observed phase-transition temperatures.
• Defining fixed and reference-point temperatures for ideal substances under ideal conditions.
• Applying a methodology for uncertainty estimation independent of specific realization challenges.

Main Results:

• The paper discusses the application of a unified methodology for uncertainty estimation in temperature measurements.
• It highlights the importance of considering non-ideal conditions, such as impurity content, in uncertainty budgets.
• Recommendations and practical experiences related to uncertainty estimation are presented.

Conclusions:

• Reliable uncertainty estimation is critical for the high-accuracy realization of international temperature reference points.
• A systematic approach to estimating uncertainties, considering all influencing physical effects, is essential for harmonizing temperature scales.
• The presented methodology provides a framework for consistent uncertainty evaluation across various temperature realization challenges.