J W Chung et al 2001 Metrologia 38 535 doi:10.1088/0026-1394/38/6/8
J W Chung, K S Ryu and R S Davis
Show affiliationsA magnetic susceptometer developed at the Bureau International des Poids et Mesures (BIPM) is used by many national laboratories to determine the magnetic properties of stainless-steel mass standards. This device relies on a small, cylindrical magnet to simulate a magnetic point dipole. According to simple theoretical considerations, (a) the uncertainty in the magnetic moment contributes weakly to the combined uncertainty of any measured susceptibility provided that unknowns are measured relative to a standard of similar size; (b) a cylindrical magnet with a height-to-diameter ratio of 0.87 best approximates a point dipole; and (c) the magnetic moment of the cylindrical magnet used can be determined by the susceptometer itself. Experimental tests of these assertions are presented. The properties of the cylindrical magnet generally become more important when determining the susceptibility of "small"-sized samples relative to a "large" standard. Small samples provide additional challenges, which are discussed in the context of a more general uncertainty analysis.
06.20.Dk Measurement and error theory
07.55.Jg Magnetometers for susceptibility, magnetic moment, and magnetization measurements
Issue 6 (December 2001)
J W Chung et al 2001 Metrologia 38 535
P W Martin 2000 Metrologia 37 185
N Brown et al 2000 Metrologia 37 107
R S Davis 1998 Metrologia 35 49
M T Clarkson et al 2001 Metrologia 38 17
P W Martin 2001 Metrologia 38 377
A Picard and H Fang 2002 Metrologia 39 31
V I Sapritsky 1995 Metrologia 32 411
K Rasmussen 1999 Metrologia 36 265
A Lassila et al 2000 Metrologia 37 701