[time-nuts] Maser manual

Magnus Danielson magnus at rubidium.dyndns.org
Wed Sep 1 20:01:45 UTC 2010


On 09/01/2010 09:39 PM, Poul-Henning Kamp wrote:
> In message<24C547B54EA34A69BACC4F823BB4036F at pc52>, "Tom Van Baak" writes:
>> I found the original copies of both EFOS manuals, along with
>> a few photos. See:
>>
>>     http://www.leapsecond.com/museum/efos/
>
> Interesting.
>
>
> Page 4/3 in the service manual states:
>
> 	For the Hydrogen Maser, this unperturbed frequency
> 	is
> 		f(H) = 1 420 405 751.768 +/- 0.002 Hz
>
> 	In practice, this frequency is perturbed by
> 	interaction of the hydrogen atoms with the walls
> 	of the interaction volume container, doppler
> 	effects, interactions between the atoms themsel-
> 	ves, etc.  The resulting frequency for the EFOS
> 	Maser is taken to be
>
> 		F(o) = 1 420 405 751.689 Hz
>
> I have no idea where the EFOS was produced, but somebody should try
> to calculate the relativistic correction for their height above the
> geoid, and see how much of the systematic 0.079Hz frequency difference
> that explains...

Neuchatel, which still leaves a bit of unspecified height.

However, this effect would be cancelled as their cesium clocks would be 
on the same height above the geoid (give or take a few meters).

So, their indication is correct. The C-field also pulls the atoms of 
course, which they failed to point out in the cited text.

> If I were to build a maser myself, I would probably not attempt
> to copy the EFOS, as the large mechanical dimensions add significant
> cost in materials and machining.
>
> I would be much more tempted by a sapphire loaded cavity design like
> this one:
>
> http://www.nict.go.jp/publication/shuppan/kihou-journal/journal-vol50no1.2/0304.pdf)
>
> As that brings the mechanics inside the work envelope of main-stream
> CNC machines with the required tolerances.

Yes, but what is the issues relating to sapphire loading? What's the 
cost of the sapphire block and having it machined?

Cheers,
Magnus



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