J T Zhang and S Q Xue 2008 Metrologia 45 436 doi:10.1088/0026-1394/45/4/009
J T Zhang1 and S Q Xue
Show affiliationsJohnson noise thermometry comes with many imperfection effects that arise primarily from electromagnetic interference, the non-linearity of the electronic system, the transmission line error, etc. Current Johnson noise thermometers (JNTs) operate according to the principle of correlation by which interference noises would be rejected completely. Unfortunately, correlators of JNTs are observed to perform imperfectly in the elimination of these imperfection effects. This paper presents the direct imperfection effect measurements of the JNT of the National Institute of Metrology at the melting point of gallium. The result of these measurements implied that the imperfection effect of correlation acted as an equivalent input noise equally distributed on both probes of the JNT. A relation was derived in this paper to treat this equivalent input noise as a systematic error to Johnson noise thermometry. As a result, the systematic error arising from the measured imperfection effect was corrected from the measured thermodynamic temperature of the melting point of gallium.
65.40.G- Other thermodynamical quantities
Instrumentation and measurement
Issue 4 (August 2008)
Received 18 February 2008
Published 9 July 2008
J T Zhang and S Q Xue 2008 Metrologia 45 436
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