The Thermal Metrology Department carries out research in fields pertinent to the CCT (Comité Consultatif de Thermométrie) and more precisely projects are activated concerning the definition of the International Temperature Scale of 1990 (ITS-90), hygrometry and thermal properties of materials (thermophysical, radiative, thermodynamic and chemical-physical properties).
The Department takes part and coordinates international research projects (16 EUROMET projects and 4 coordination) and international comparisons organised by BIPM and EUROMET (11 comparisons in 2005). Research contracts are activated to develop measurement methods and innovative instrumentation. In 2005 11 contracts were active with international and national organisations, with private enterprises and public administration.
Measurement services are offered in the areas of temperature, thermal flux, thermophysical properties, and humidity; 209 calibration certificates were issued in 2005.
A meeting was organized in November 2005, on the tenth anniversary of the passing of Prof. Luigi Crovini, the scientist of international fame who guided the Italian school of thermometry to top scientific levels. On that occasion, the Thermal Metrology Building was dedicated to his memory, thus becoming the "Luigi Crovini Building".
The experimental activities were focused on the finalisation of the measurements with the interpolating constant-volume gas thermometer (ICVGT) in order to extend in 2006 INRIM temperature standards from 25 K to 4 K and to obtain the MRA international equivalence for them. The functional development and testing of the new cryogen-free automatic cryostat was finalised, for the realisation of the ITS-90 above 25 K.
A new cryogen-free refrigerator was acquired, which will allow to work down to 1.5 K without any further need of liquid helium, thus cutting the costs of most of the studies performed at INRIM.
Finally, an action promoted and started in 2004 in the framework of the Italy (MAE)-China scientific agreement, allowed to re-start production in China of accurate RhFe thermometers, no longer available from any other source in the world for some years now. They are necessary for studies below 25 K. The first series of these new thermometers has been bought by INRIM and other 5 NMIs worldwide.
Cryogenic temperature sealed fixed-points (each 10 mm in diameter).
Activities in contact-thermometry for long-stem thermometers were focused on the regional extension of CCT Key Comparison K4, regarding comparisons at the freezing points of aluminium and silver. The results of previous comparisons, the regional extension of CCT Key Comparisons K3 and K7 were published in Metrologia. Key Comparison K7 involved water triple point cells, where the thermodynamic temperature of the water triple point defines the kelvin. This work led to Recommendation T1 of the CCT, taken over by the CIPM with Recommendation CI-2005, specifying a reference isotopic composition for the water sample in water triple point cells and the means to correct for non-reference compositions.
Research activities on the definition of the International Temperature Scale by means of vapour pressure scales, between 200 °C and 1000 °C, continued under the EUROMET project 772 coordinated by INRIM. All the control systems devoted to temperature and pressure control for Gas Controlled Heat Pipes (GCHPs) have been concluded, assembled, tested and characterised. The complete system is now operative and represents the key point for the realisation of the Temperature Amplifier, proposed by IMGC, and agreed by ten other European laboratories. The first new mercury GCHP is also now in operation, giving the first promising results in terms of temperature uniformity and stability.
Set of fixed-point cells.
In the framework of research contracts with two metrological institutes, IPQ (Portugal) and NMC (Singapore), the radiation thermometry group has been working to develop various thermometric apparatus. Two precision IR thermometers (InGaAs based thermometers covering the range from 150 oC to 1100 oC with a NETD of less than 4 moC at 150 oC), one indium fixed-point (156 oC) cell and a furnace for fixed-points realisation, have been constructed, fully characterised and delivered to the two Institutes. Training courses at IPQ and NMC have been held on the use of the instruments.
The activity on Pt/Pd thermocouples continued and the new transfer source for the high temperature calibration from 900 oC to 1500 oC was completed and fully characterised. The new furnace makes for easier operation and a more extended uniform region can be obtained, thus improving the matching of the thermocouple with the blackbody cavity. Five Pt/Pd thermocouples have been constructed and characterised to replace the presently used Pt/Pt-Rh alloy thermocouples as secondary reference standard.
High temperature furnace for calibration of Pt/Pd thermocouples.
The Institute has been engaged in the development of a standard for the calibration of contact thermometers. The activity, which is aimed at filling the lack of a national reference, has been focused on the development and modelling of a reference system and thus, on the metrological calibration of a first system prototype.
The development of fiber optic transfer standards thermometers for biomedical and industrial applications called for the improvement of fluorescence decay measurement techniques. Promising results have been obtained in a recent study from the comparison of time and frequency domain signal processing methods.
Thermal fluid- dynamic model of the reference system as obtained with the finite element method.
An extension of the humidity measurement range towards low water vapour concentrations (< 10-6mol/mol) is called for several scientific and industrial applications, from microelectronics to gas production. The completion of a "hybrid" humidity generator (based on saturation and dilution), which is able to produce concentrations between 10-7mol/mol and 10-5mol/mol, answers to these needs. Cooperation with the South-Tyrol Archaeological Museum (in Bolzano), for the development of measurement methods and instruments aimed at ensuring measurement traceability in the Iceman mummy conservation system, has been set up.
In order to preserve the most ancient "wet" mummy in the world, the thermo-hygrometric conditions that have allowed its preservation up to the present day (at low temperature in water saturated air) must be carefully reproduced. To this end, state-of-the-art measurements are required in the conservation cell as the air temperature must be stable to within 0.05 oC at 99 % relative humidity.
Measurements in the conservation cell carried out in co-operation with the museum
(Courtesy of the South-Tyrol Archaeological Museum).
During 2005, IMGC has provided, as principal contractor, an essential contribution for the start in September of the public website of the European funded project Evitherm. In addition, F. Pavese has provided the basic Drafts of the Constitution and other legal documents necessary to install a new permanent legal entity, "the evitherm Society", of which F.Pavese is now the Vice President for Metrology. This legal entity will promote activities in the field of thermal metrology and provide a link between the laboratories and the enterprise.
By the end of 2005 the European Thematic network FP5 "SofTools_MetroNet" has came to an end. It grouped 24 partners plus another 15 members worldwide and had its last Conference AMCTM in Lisbon in June. The corresponding VII book of the series is now published.
Two are the main followups of these activities:
- The activities in the new framework IMEKO Technical Committee TC21 "Mathematical Tools for Measurement", established at the end of 2004 (Chairperson: F.Pavese)
- The new EUROMET/iMERA Joint Research Project "SofTools", which has some 40 participants as a followup of the Network activities.
Finally, in the framework of Euromet INTMET, a focus group "mathematics and software" has been formed. The corresponding scientific activities of the Group produced a number of published papers.
In addition, strong activity continued in the framework of a Contract with CERN, for the analysis of the calibrations of some 5000 LHC cryogenic thermometers.