[time-nuts] GSP clock stabilitiy, Rb vs Cs

Bob Camp lists at rtty.us
Mon May 6 07:35:12 EDT 2013


Fountain's don't work very well in zero G….:)


On May 6, 2013, at 12:23 AM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> On 05/06/2013 02:29 AM, Mike S wrote:
>> On 5/4/2013 2:40 PM, Attila Kinali wrote:
>>> Can anyone shed some light on why the GPS Cs beams have a worse stability
>>> than the Rb vapor clocks?
>> I don't know, but it makes me wonder about things like
>> 1) How sensitive is each to C-field tuning - i.e. for the same change in
>> C-field, by how much does each type change in relative frequency? (or
>> maybe it's exactly the same, I know nothing about the Zeeman effect) I'd
>> think there would be orbital changes in frequency, after all, it's
>> orbiting a big magnet.
> Rubidium is more sensitive to C-field than Caesium.
>> 2) How tight a lock can be obtained on each? i.e. might the physical
>> realizations of Rb clocks have a higher Q-factor?
> The Q-value depends on the observation time, and for a Cs-beam this translates into beam-length assuming constant speed. Foutains has much better Q since they have longer observation time. H-masers started as a beam with a "bounce-box" to prolong the observation time.
> Cheers,
> Magnus
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