Design and Performance of the New 1-m NRC Primary Cesium Clocks

Three new primary cesium clocks with an interaction length of 1 m are now in operation at the National Research Council (NRC). Used as secondary clocks since late 1978 and as primary clocks since December 1979, they have an expected lifetime of up to 25 years, an accuracy limit of 1.5 X 10-13, a 24-h frequency stability ?(2, ?) of less than 2 X 10-14, and agree in frequency to better than I X 10-13 with the NRC primary clock CsV.