KEY COMPARISON

 

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Abstract

The delegates of the CCEM discussion meeting on international comparisons in magnetism recommended in May 2000 in Sydney that a worldwide intercomparison of magnetic flux density by means of a transfer standard coil should be proposed in addition to and in accordance with the EUROMET project No 446.

A field coil of the Garret type was prepared and provided as transfer standard by PTB acting again as pilot laboratory. The single layer coil produces a field with a flux density of about 2 mT if it carries the maximum permitted current of 1 A. This standard was circulated in 2001 and 2002 to nine other national metrology institutes worldwide.

The standard coil has also be used to compare the ac field calibration set-ups of the various laboratories. In order to provide a frequency response different to that of the standard used for the EUROMET comparison, the current distribution network at both flanges of the standard coil had been modified with the result that the frequency dependence of the coil constant shows a minimum at f = 4 kHz.

Each participant was asked to apply the measuring methods and to use the equipment as available for his daily work to tranfer the unit of magnetic dc and ac flux density. So, quite different methods have been applied within the intercomparison.

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 CCEM, according to the provisions of the Mutual Recognition Arrangement (MRA).

Dates

Issue 1A ( 1 January 2005)