Comment on 'Evaluation of the primary frequency standard NPL-CsF1'

摘要

A recent evaluation of the accuracy of the National Physical Laboratory (NPL) primary frequency standard NPL-CsF1 by K Szymaniec et al (2005 Metrologia 42 49-57) reported an overall frequency uncertainty of delta nuu(0) = 1 x 10(-15). This stated uncertainty includes a correction of a frequency bias of delta nuu(0) = 8 x 10(-16) +/- 3 x 10(-16) attributed by the authors to microwave leakage. We believe that the stated cause of the frequency bias, its magnitude and its stated uncertainty are in error.