[time-nuts] Cesium vs H Maser clocks

[Tom Van Baak]

> Tom,
> 
> The conceptual deadlock that I would overcome is whether
> adjusting the C-field the Cs resonance varies, as this would
> impact the defition of the "second".
> 
> Thanks,
> Antonio I8IOV

Correct, the C-field can vary and it has a slight impact on the
accuracy of the seconds that your Cs clock is generating. So
that's why it's very important for the best of primary standards
to get the C-field right. And they do. Half the work is making a
stable clock; the other half is understanding what apparatus you
have made and turning it into an accurate clock, with a detailed
series of experiments.

If you really get into the details of the physics, remember that no
commercial or laboratory Cs clock actually resonates at precisely
9 192 631 770.000 Hz. There are corrections for magnetic fields,
velocity of atoms, temperature, cavity design, even for gravity; a
whole bunch of interesting effects.

For a great example of the level of care that goes into the design
and calibration of a primary cesium standard read papers like:

< Accuracy evaluation of NIST-7>
http://tf.nist.gov/timefreq/general/pdf/1497.pdf

<Accuracy evaluation of NIST-F1>
http://tf.nist.gov/timefreq/general/pdf/1823.pdf

Or, for an informal description of C-field and Cs standards see:

<HP 5062C Theory of Operation>
http://www.leapsecond.com/museum/hp5062c/theory.htm

/tvb