Detailed program

• Imeko TC12 Chair welcome address (Davor Zvizdić)
• CCT WG-Humidity vice-chair and ISHM symposium chair welcome address (Stephanie Bell)
• Tempmeko/ISHM 2025 IPC chairs welcome address (Xiaojuan Feng and Vito Fernicola)
• Tempmeko/ISHM 2025 Organising Committee Chair welcome address (Mohamed Sadli)
• Official opening address from Cnam (Thierry Horsin)

Introductory talk from Dr Martin Milton, Director of the BIPM:  : « 150 years of the BIPM: the early years of length, mass and temperature metrology »

Professor Peter Thorne (ICARUS Climate Research Centre at Maynooth University, Ireland) « A climate scientist's perspective on our imperfect historical and ongoing measurements of the climate system »
Abstract :
As a climate scientist who has grappled with our imperfect historical observations for over two decades in this talk I will provide some highlights and lowlights of the use and abuse of historical measurements of temperature with a side-serving of humidity (and a large portion of humility). I will also discuss the process behind how we arrive in IPCC reports at the assessment findings that garner headlines around the globe. Finally, I will touch upon the foundational and largely invisible work behind the scenes around the governance, collation and preservation of both historical and ongoing observations.
 

Hisashi Abe (NMIJ) « Water Measurement on the Moon and Earth »
Abstract :
It has been more than half a century since the first humans landed on the Moon during the Apollo 11 mission. Recently, the National Aeronautics and Space Administration (NASA) has established a lunar exploration program, called the Artemis program, to send humans to the Moon again. International cooperation with partner agencies, including the Japan Aerospace Exploration Agency (JAXA), is also planned in this program. A long-term goal of Artemis is to build a base camp on the Moon. To achieve this, one of the most important initial tasks is to explore lunar water, which is a potential resource for fuel (hydrogen and oxygen), breathable oxygen, and drinking water. In addition, the measurement of the isotopic ratios of lunar water is of great interest, as it would provide valuable information on the origin of lunar water, which is deeply relevant to the history of the Earth–Moon system.
 
Recently, JAXA formally initiated the Lunar Polar Exploration mission (LUPEX) to investigate the quantity and distribution of water on the Moon. The mission plans to send instruments to the Moon’s south polar region. The National Metrology Institute of Japan (NMIJ) is collaborating on the mission and is responsible for developing an instrument capable of measuring trace amounts of water vapor (trace moisture). Cavity ring-down spectroscopy (CRDS) was selected for the instrument. NMIJ successfully developed a prototype miniaturized trace-moisture sensor based on CRDS (mini-CRDS), which is small, lightweight, and robust. This technology is also applied on Earth, particularly in trace-moisture measurement of high-purity gases used in the semiconductor industry.
 
In this talk, first, the history of lunar water is briefly reviewed. Second, a short introduction to LUPEX is given. Finally, details of the development of the mini-CRDS and its industrial applications, as well as other CRDS-based systems recently developed at NMIJ, are presented.
 

Michel Piat (Université Paris Cité) « The Cosmic Microwave Background: why ultra-low temperatures are key to precision cosmology »
Abstract :
The Cosmic Microwave Background (CMB) is the remanent light from the early Universe, emitted approximately 300,000 years after the Big Bang. Its spectrum represents the most accurate blackbody ever measured, with a temperature of 2.725 K ± 0.002 K, as determined by the FIRAS instrument onboard the COBE satellite launched in 1989. Tiny temperature fluctuations, at the level of 100 parts per million, were first detected by COBE’s DMR instrument. These anisotropies primarily originate from primordial density perturbations at the time of CMB emission, which later grew into the large-scale structures we observe in the Universe today. Comparing these temperature anisotropies with theoretical models allows for stringent constraints on cosmological parameters that describe the composition and evolution of the Universe.
The Planck satellite, launched in 2009, produced the most precise full-sky map of these temperature fluctuations, leading to percent-level precision on key cosmological parameters. Achieving this required the High Frequency Instrument (HFI) on Planck to operate 52 bolometers cooled to 100 mK.
Future challenges in CMB physics lie in two main directions:
(i) achieving ultra-sensitive measurements of CMB polarization at the 0.1 ppm level, which could provide insights into inflation — a hypothesized period of rapid expansion just after the Big Bang;
(ii) measuring the CMB spectral distortions at the 10⁻⁸ level, which could reveal energy injection processes in the early Universe.
In this talk, I will present the origin and importance of the CMB, and discuss how its precise measurements inform our understanding of the Universe. I will highlight the experimental techniques used to measure the CMB, with a particular focus on the challenges of reaching ultra-low temperatures and controlling uncertainties in both detector stability and spectral measurements.

Christof Gaiser (PTB) « Thermodynamic versus ITS temperature : status quo and future prospects of the kelvin in the revised SI »
Abstract :
Since 2019, the definition of the kelvin is based on a fixed numerical value of the Boltzmann constant k. Furthermore, the Mise en pratique for the definition of the kelvin in the SI (MeP-K) [1] allows for both the realization and dissemination of thermodynamic temperature T as well as its approximation (T90), the temperature according to the International Temperature Scale of 1990, ITS 90. An improved knowledge of the differences (T  T90) is therefore of eminent importance.

In 2011, a working group of the Consultative Committee for Thermometry published their best estimates of (T  T90). Since 2011, the work on the determination of the Boltzmann-constant [2] has stimulated significant improvements in primary thermometry. A recent paper [3] updates the (T  T90) estimates by combining and analyzing the data used for the 2011 estimates and data from more recent primary thermometry. The new data has been obtained by four types of gas thermometry: acoustic, dielectric constant, refractive index, and constant volume. Their uncertainty estimates are now comparable with the uncertainties in the best measurements of thermodynamic temperature values and the uncertainties in ITS90 realizations.
 
In this presentation, the interplay between primary thermometry, temperature scales and platinum resistance thermometry in a historical perspective will be discussed briefly. After a short introduction to primary thermometry in general and the established contact- and non-contact techniques within the MeP-K, some applications for the best estimates (T  T90) will be given. Focus will lie on the challenges connected with thermodynamic temperature measurement above 300 K and the advantages and disadvantages of the different techniques. Finally, the status quo will be summarized and possible future prospects will be sketched.

References 
[1] https://www.bipm.org/en/publications/mises-en-pratique 
[2] J Fischer, B Fellmuth, C Gaiser, T Zandt, L Pitre, F Sparasci, M D Plimmer, M de Podesta, R Underwood, G Sutton, G Machin, R M Gavioso, D Madonna Ripa, P P M Steur, J Qu, X J Feng, J Zhang, M R Moldover, S P Benz, D R White, L Gianfrani, A Castrillo, L Moretti, B Darquié, E Moufarej, C Daussy, S Briaudeau, O Kozlova, L Risegari, J J Segovia, M C Martín and D del Campo  "The Boltzmann project", Metrologia 55 R1 (2018) 
[3] C. Gaiser, B. Fellmuth, R. M. Gavioso, M. Kalemci, V. Kytin, T. Nakano, A. Pokhodun, P. M.C. Rourke, R. Rusby, F. Sparasci, P. P.M. Steur, W. L. Tew, R. Underwood, R. White, I. Yang, J. Zhang "2022 Update for the Differences Between Thermodynamic Temperature and ITS 90 Below 335 K", J. Phys. Chem. Ref. Data 51, 043105 (2022) 
 

Andrew Todd (NRC) « Quantum technologies for temperature measurement : how we got here and where we might be going »
Abstract :
Since its emergence in the early 20th century, quantum mechanics has become one of the most influential foundations of modern physics. Although often counterintuitive, it has enabled many of the technologies we depend on today and will continue to drive breakthroughs in computing, sensing, and communications.

In this presentation, we trace the parallel yet interconnected developments of temperature measurement and quantum mechanics and explore unresolved challenges in temperature metrology and the potential of quantum-based technologies to address them. While not an exhaustive or deeply technical review, we will highlight several current quantum thermometry techniques including noise thermometry, Coulomb blockade thermometry, Rydberg atom-based thermometry, and nitrogen-vacancy centre thermometry. For each, we will discuss their operating principles, current progress, and remaining challenges.

Finally, we will look ahead to emerging sensors and techniques that could significantly influence the future of temperature metrology. 

Panellists and subjects :

• Jonathan Pearce : in-situ temperature calibrations and traceability to SI
• Jan Nielsen : moisture in solid fuels
• Stephanie Bell : humidity in energy gases
• Stephen Sweeney : challenges of temperature measurement in semiconductor industry
• Jürgen Hartmann : challenges of thermophysical quantities measurements in industry

• Conclusion from the organisers : key numbers of participation and the next steps
• Official closing of the symposium by Maguelonne Chambon (LNE)