The examination of base parameters for ITS-90 scale realization in radiation thermometry
Project Description
The project will consist of the measurement and examination of the base parameters associated with radiation thermometry primary ITS-90 scale realsation above 961.78 °C.
A number (2 or 3) of radiation thermometers will be circulated to the participating laboratories. Each participant will measure, within the limits of its capabilities, the fundamental parameters necessary for an ITS-90 primary scale realization. At the end of the circulation the laboratory supplying the radiation thermometer, to evaluate the effect of instrumental drifts, will perform a repeat measurement of all parameters.
The parameters to be measured are: size of source effect (SSE), linearity and mean effective wavelength
This project is necessary for two reasons:
a) It will allow for the first time the fundamental parameters underlying a primary realisation of the ITS-90 by radiation thermometry to be compared and participant capabilities evaluated.
b) The CCT-WG5 is in the process of writing a document on the evaluation of uncertainties in the scale realisation of ITS-90 by radiation thermometry. This project will provide a rigorous basis for the uncertainties associated with the various input parameters.
In addition the scale realization depends upon fixed-point blackbody sources of Ag, Au or Cu. The emissivity of these sources is determined by numerical calculation. A standard set of blackbody designs will be developed and their emissivity calculated using each participant’s software, thus providing a benchmark to the reliability of such software.
IMGC, PTB, NPL have volunteered thermometers for use in the comparison but the PTB, NPL thermometers will not be available until Spring 2003.
The project is open to those who can measure two or more of the quantities under investigation.
It is envisaged that a follow on project in the mid-temperature range 156 °C to 961 °C could be considered.
Final Report 2011-03-11
The project has been completed and results are available in the KCDB.
Progress Report 2004-04-30
Following agreement of the protocol by the participants the comparison started in July 2003, with two thermometers (a Vega TSP2 belonging to IMGC and a LP3 belonging to PTB) being circulated. So far measurements have been performed by NPL (the starting laboratory), VSL and PTB, and measurements are currently underway at CEM. Measurement reports are due to be received from PTB and VSL.
Unfortunately, a problem occurred with the Vega TSP2 thermometer while it was at PTB and it has had to be withdrawn from the comparison. The circulation will continue with the LP3 only. However, the NPL and VSL TSP2 results can still be used and will provide some useful data.
The circulation schedule is currently 2 to 3 weeks behind that outlined in the protocol. However, since the withdrawal of the TSP2 thermometer means that the number of measurements to be done at each laboratory is now much reduced, this delay is likely to disappear. In any case, the project is still expected to finish on time, in October 2005.