[time-nuts] Fwd: rare stuff available (National Company NC-1001 Atomichron)

Magnus Danielson magnus at rubidium.dyndns.org
Mon Dec 14 01:13:57 UTC 2009


John Miles wrote:
> I think a lot of the later development work on cesium-beam standards was
> aimed at reducing their physical size, cost, and maintenance requirements.
> Unlike miniaturized, mass-produced, hermetically sealed tubes, the
> Atomichron's tube was probably built in a way that permits disassembly and
> restoration by someone who's comfortable with vacuum systems.

You would need to open it up, clean it, replace the masspectrometer, 
vacuum pump, and then seal it, check vacuum and also eventually insert 
new Cesium. I'd expect this part of the restoration would be a bit of a 
challenge for most.

> The tube itself is very long, so if it's late enough to incorporate a Ramsey
> cavity, then it probably has a narrow line width.  SNR might be a different
> story.

It has a Ramsey cavity. The length of the tube was motivated by line 
width properties. The Ramsey cavity has a length of about 100 cm giving 
a line-width of about 120 Hz [1]. I suspect the Atomichron was running 
the Cesium source hotter than modern short tubes.

> The rest is just standard post-WWII era microwave hardware, with a block
> diagram that doesn't look all that different from later models.  I'll bet it
> wouldn't be that hard to get it working again.  That'd be cool as hell.

The microwave hardware and such should not pose a problem to someone 
knowing the field, neither should most of the other electronics. But I 
would expect some time and effort to go into that field.

[1] http://tf.nist.gov/general/pdf/1663.pdf

Cheers,
Magnus



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