European Metrology Research Project Research Articles

Precision Measurements of Beta Spectra using Metallic Magnetic Calorimeters within the European Metrology Research Project MetroBeta

MetroBeta, a recently completed European Metrology Research Project, aimed at the improvement of the knowledge of the shapes of beta spectra, both in terms of theoretical calculation and measurement. The most prominent experimental work package concerned the measurement of the spectrum shapes of several beta decaying radionuclides by means of metallic magnetic calorimeters (MMCs) with the beta emitter embedded in the absorber. New MMC chips were designed and optimized for five different absorber heat capacities, enabling the measurement of beta spectra with Q values ranging from few tens of keV up to ~ 1 MeV. Several beta spectra were measured with high energy resolution and statistics of up to 107 counts.

Round robin comparison study on the form measurement of optical freeform surfaces

A round robin comparison of freeform form measurements was carried out by the project partners and stakeholders of a European metrology research project. Altogether six measuring instruments were considered: five different (pointwise and areal) optical devices and one tactile device. Three optical freeform surfaces were used for the comparison measurements, where two specimens were measured by five instruments and one specimen by four instruments. In this paper, the evaluation methods and results of this round robin are presented for the three freeform surfaces made from a temperature-stable material, Super Invar ®. The freeforms had diameters of 40 mm, 50 mm and 100 mm and best-fit radii of 39.75 mm (convex), 40.9 mm (convex) and 423.5 mm (concave). For comparison, the bilateral pointwise differences between the available measurements were calculated. The root-mean-square values of these differences ranged from 15 nm to 110 nm (neglecting spherical contributions) and provided an insight into the status of typical freeform measurement capabilities for optical surfaces.

Beta spectrometry with metallic magnetic calorimeters in the framework of the European EMPIR project MetroBeta

The aim of the European Metrology Research Project MetroBeta is to improve the knowledge of the shapes of beta spectra, both in terms of theoretical calculation and measurement. The precise knowledge of beta spectra is required for the activity standardisation of pure beta emitters. Metallic magnetic calorimeters (MMCs), a type of cryogenic detectors, with the beta emitter embedded in the absorber have proven to be among the best beta spectrometers, in particular for low-energy beta transitions. Within this project, new designs of MMCs optimized for five different beta energy ranges were developed and a new detector module was constructed. The beta spectra of 151Sm, 14C and 99Tc have been measured so far; additional measurements with 36Cl are under preparation. Improved theoretical calculation methods and complementary measurement techniques complete the project.

WMO Interlaboratory Comparison in Europe with Loops Linkage and Data Processing

Abstract This article describes the interlaboratory comparison (ILC) of meteorological and hydrological calibration laboratories in the field of temperature (−30° to 40°C), humidity (10%–95% RH at room temperature), and pressure (800–1100 hPa). The ILC was organized by the World Meteorological Organization (WMO) Regional Instrument Centre (RIC) at the Slovenian Environment Agency and University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality as an accredited interlaboratory comparison (proficiency testing) provider according to the ISO/IEC 17043:2010 standard. The ILC was organized in the target area of WMO Regional Association VI (Europe). The protocol and procedure for ILC were developed within European Metrology Research Project (EMRP) MetoMet2. The participants used their standardized procedures for calibration. Because of the large number of participating laboratories (18) from 17 countries, the ILC was organized in two loops, which were linked via four linking laboratories and evaluated using the En number. The equipment used in both loops exhibited stability and uncertainty, which enabled evaluation of the laboratories’ capabilities. The article presents the data processing, the linkage procedure, and the main results for all three categories (temperature, humidity, and pressure). It was observed that some of the laboratories had unusually low uncertainties. From the metrological point of view, the authors present some comments and suggestions to the laboratories, the results of which differ from the reference ones. The conclusions can help also other meteorological laboratories and organizations that did not participate in the ILC with their everyday work.

Metrology for Radiological Early Warning Networks in Europe ("METROERM")-A Joint European Metrology Research Project.

As a consequence of the Chernobyl nuclear power plant accident in 1986, all European countries have installed automatic dosimetry network stations as well as air sampling systems for the monitoring of airborne radioactivity. In Europe, at present, almost 5,000 stations measure dose rate values in nearly real time. In addition, a few hundred air samplers are operated. Most of them need extended accumulation times with no real-time capability. National dose rate data are provided to the European Commission (EC) via the EUropean Radiological Data Exchange Platform (EURDEP). In case of a nuclear emergency with transboundary implications, the EC may issue momentous recommendations to EU member states based on the radiological data collected by EURDEP. These recommendations may affect millions of people and could have severe economic and sociological consequences. Therefore, the reliability of the EURDEP data is of key importance. Unfortunately, the dose rate and activity concentration data are not harmonized between the different networks. Therefore, within the framework of the European Metrology Research Programme (EMRP), 16 European institutions formed the consortium MetroERM with the aim to improve the metrological foundation of measurements and to introduce a pan-European harmonization for the collation and evaluation of radiological data in early warning network systems. In addition, a new generation of detector systems based on spectrometers capable of providing both reliable dose rate values as well as nuclide specific information in real time are in development. The MetroERM project and its first results will be presented and discussed in this article.

Experimental evaluation of the performance of humidity analyzers in natural gas under industrial conditions

The work reported is the continuation of the extensive comparison performed in controlled laboratory conditions using natural gas from the Spanish grid, as part of the European Metrology Research Project (EMRP) “Characterisation of Energy Gases” (ENG01-Gas, 2009). One of the outcomes of the project was the good performance of a laser absorption spectrometer with respect to other measurement technologies, in particular the absence of appreciable drift effects, exhibited by aluminium oxide (Al2O3) sensors that are traditionally used in the natural gas industry. The investigation was performed over a wide range of humidity content (13 ppmv to 250 ppmv) in ambient conditions of 23 °C ± 3 °C, at Enagás central laboratory in Zaragoza, Spain (Gallegos et al., 2015).We report the subsequent comparison of two laser absorption analyzers, from different manufacturers, and a conventional Al2O3 installed on site in real industrial conditions, at an underground gas storage (UGS) and drying plant of Enagás in Serrablo, Spain. The performance of sensors is reported and discussed for all production stages of the plant (extraction, injection and shutdown), during which extreme ambient temperature values took place (from −15 °C up to 40 °C) and at line pressures up to 6.7 MPa. A purpose built sampling system was designed and constructed to accommodate the different instrumentation requirements and ensure an optimum metrological analysis.The new results are compared with those previously obtained under more ideal laboratory conditions in the context assuring compliance with the contractual specifications that are to be met in Europe (EASEE-gas, 2005).

Comparison of asphere measurements by tactile and optical metrological instruments

A comparison of topography measurements of aspherical surfaces was carried out by European metrology institutes, other research institutes and a company as part of an European metrology research project. In this paper the results of this comparison are presented. Two artefacts were circulated, a small polymer coated aspherical lens with a clear aperture of about 12 mm, and a large conical convex lens with a clear aperture of 300 mm developed for the ESO Very Large Telescope. The participating laboratories were allowed to follow their own measurement strategies. Both tactile and optical measuring instruments were used, as well as single point and imaging techniques. The measured data were compared with respect to the root-mean-square (RMS), peak-to-valley and Zernike polynomial representations of the measured deviations from the nominal shape. The comparison shows for five out of eight measuring instruments/methods a very good agreement of the measured topographies within 14 nm (RMS).

A novel radionuclide-specific detector system for the measurement of radioactivity at steelworks

A new instrument to detect radioactive contamination in cast steel, slag and fume dust from steelworks is proposed. It is based on an electrically cooled HPGe detector. Experimental data presented show that it matches the requirements of the European Metrology Research Project “MetroMetal” and can replace, with significant advantages, existing equipment. The advantages (energy resolution, better nuclide identification) over common systems (scintillators) as well as drawbacks (lower efficiency) are discussed and typical MDAs values are presented together with the results from measurements of reference sources.

Electrolytic Conductivity as a Quality Indicator for Bioethanol

We present results of the European Metrology Research Project on the SI traceability of electrolytic conductivity measurements in bioethanol. As a first step to this aim secondary conductivity measurements have been performed to characterize reproducibility, stability, measurement uncertainty and the significance of the measurement results. The relative standard measurement uncertainty is of the order 0.3%, while inter-laboratory reproducibility is around 6.9%. The measured conductivities of two samples from different sources show a relative difference of around 30%. These results show that conductivity is an appropriate quality indicator for bioethanol. However, it also demonstrates that inter-laboratory reproducibility has to be improved, in particular with respect to SI traceability.

Miniature Fixed-Point Cell Approaches for $${{\varvec{In\,Situ}}}$$ I n S i t u Monitoring of Thermocouple Stability

In the framework of the European Metrology Research Project ENG08 “MetroFission,” LNE-Cnam and NPL have undertaken cooperative research into the development of temperature measurement solutions for the next generation of nuclear fission power plants. Currently, in-pile temperature monitoring is usually performed with nickel-based (Type K or N) thermocouples. When these thermocouples are exposed to a neutron flux, the thermoelements transmute, leading to large and unknown drifts in output. In addition, it is impossible to routinely recalibrate the thermocouples after irradiation for obvious reasons of safety. To alleviate this problem, both LNE-Cnam and NPL have developed, via differing approaches, in situ calibration methods for the thermocouples. The self-validating thermocouple methodologies are based on the principle of a miniature fixed-point cell to be co-located with the thermocouple measurement junction in use. The drift of the thermocouple can be monitored and corrected for by regular determination of the output at the phase transition of the fixed-point material: in effect performing regular in situ calibration checks. The two institutes have constructed miniature fixed-point cells for use at three different temperatures; the freezing point of silver $$(961.78\,^{\circ }\mathrm{C}$$ ; LNE-Cnam), the freezing point of copper $$(1084.62\,^{\circ }\mathrm{C}$$ ; LNE-Cnam and NPL), and the melting point of Fe–C ( $${\sim }1154\,^{\circ }\mathrm{C}$$ ; NPL). This paper introduces the construction and validation of the miniature fixed-point cells prior to use, to ensure traceability to the ITS-90. A comparison of the performance of the two cell designs is discussed, where typical industrial Type N thermocouples have been used for measurement of the fixed-point cells. Such initial measurements demonstrate the feasibility of each of these two approaches.

Mesure de la permittivité complexe de liquides de référence pour la détermination du débit d’absorption spécifique (DAS)

This paper presents our work for the measurement of the complex permittivity of liquids, carried out in the framework of a European Metrology research project entitled “Traceable measurement of field strength and SAR for the Physical Agents Directive”. One of the aims of this project was to establish the traceability of the specific absorption rate measurements to the SI up to 10 GHz. We use a vector network analyser to measure the S 21 parameter of coaxial cells containing the liquid under test (a reference liquid or an equivalent tissue liquid). The method does not require the network analyser to be calibrated in terms of impedance. In fact, only the length of the coaxial cell and the working frequency need to be known.