L O Becerra 1, W Bich 2, N Bignell 3, G D Chapman 4, J W Chung 5, S Davidson 6, M Gläser 7, A Gosset 8, Z J Jabbour 9, W G Lee 5, A Ooiwa 10, P Richard 11, R Spurny 12, A Torino 2, J Verbeek 13 and L Q Zhang 14
1
Centro Nacional de Metrologia (CENAM), CP 76900 Qerètaro, Mexico
2
Istituto di Metrologia G Colonnetti (IMGC), 10135 Torino, Italy
3
Commonwealth Scientific and Industrial Research Organization (NML-CSIRO), Lindfield NSW 2070, Australia
4
National Research Council of Canada (NRC-CNRC), K1A 0R6 Ottawa, Canada
5
Korea Research Institute of Standards and Science (KRISS), 305-600 Taejon, Republic of Korea
6
National Physical Laboratory (NPL), Teddington, Middlesex TW11 0LW, UK
7
Physikalisch-Technische Bundesanstalt (PTB), 38023 Braunschweig, Germany
8
Bureau National de Métrologie (BNM-LNE), 75141 Paris, France
9
National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899-8221, USA
10
National Institute of Advanced Industrial Science and Technology (NMIJ/AIST), Ibaraki 305-8563, Japan
11
Swiss Federal Office of Metrology and Accreditation (METAS), 3003 Bern-Wabern, Switzerland
12
Slovak Metrological Institute (SMU), 84255 Bratislava, Slovakia
13
Van Swinden Laboratorium (NMi/VSL), 2600 Delft, Netherlands
14
National Institute of Metrology (NIM), 100013 Beijing, China
L O Becerra et al 2003 Metrologia 40 07004
A key comparison concerning mass determination of five mass standards has been carried out under the auspices of the Comité Consultatif pour la Masse et les Grandeurs Apparantées (CCM) from March 1998 to March 1999. The nominal values of the mass standards were 100 mg, 2 g, 20 g, 500 g and 10 kg. The fourteen participants have been divided into three groups and the corresponding three sets of standards have been circulated within the groups in parallel. The pilot laboratory, PTB, has measured the volumes, the centres of gravity and the magnetic susceptibilities of the standards before the circulation and has communicated these values to the participants. PTB has also verified the stability of all travelling standards in advance. The majority of the instabilities of the standards during their circulation were insignificant. They have been considered for the evaluation of the results. Table 1 shows the results reported by the laboratories. A first evaluation based on the combined standard uncertainties and referred to the pilot laboratory's results has shown a few outliers, see figures 1 to 5. The participants decided therefore to choose the median as a 'robust' reference value. Tables 5 to 9 show the differences and associated uncertainties between the laboratories in the form of matrices. The degrees of equivalence of the participating laboratories for each of the five mass determinations are presented in table 11 and are shown in figures 6 to 10. These results are associated with the expanded uncertainties referred to a confidence level of 95%. They show no outliers except for two at 500 g and one at 20 g. No laboratory had more than one outlier of the five results. This key comparison can therefore be considered as very successful.
Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the Mutual Recognition Arrangement (MRA).
Issue 1A (Technical Supplement 2003)
L O Becerra et al 2003 Metrologia 40 07004
Nile Oldham et al 2003 Metrologia 40 01003
J Terrien 1972 Metrologia 8 99
L Vitushkin et al 2002 Metrologia 39 407
T Kluge et al 2007 Phys. Med. Biol. 52 N467