26.09.2006
Comparison measurements of the CCM Working Group "Mass standards", comprising 17 National Metrology Institutes, for determining the magnetic susceptibility and the magnetization of 1 kg mass standards have been terminated.
In the CCM Working Group "Mass standards" comparison measurements for the determination of magnetic properties of three 1 kg mass standards with cylindrical, OIML and ASTM shape have been performed among 17 National Metrology Institutes. Pilot laboratory was the National Research Council of Canada (NRC, today: NRC-INMS). The task was to determine the magnetic susceptibility (ranging from 0.0025 to 0.35), the residual magnetism ( permanent magnetic polarization) and the corresponding measurement uncertainties of the three weights. Before and after a comparison petal the magnetic susceptibility and the magnetization of the transfer standards were measured at the pilot laboratory. The values determined at PTB are in very good agreement with the results of the other participants (Figure 1). Only the cylindrical weight's magnetic susceptibility deviates slightly from the median of all participants, probably due to strong local variations of the magnetization inside the mass standard.
Figure 1: Measurement results for the susceptibility of all participants (1 kg OIML-shaped weight). Errors bars (red lines) correspond to the standard uncertainty (k = 1), the dashed lines represent the standard uncertainty for the median of all participants. The report of the results was done anonymously according to the distribution of a letter code.
Ansprechpartner:
Frank Scholz, FB 1.1, AG 1.11, e-mail: frank.scholz@ptb.de