[time-nuts] Attila & Active vs Passive H Masers

[Clive Green]

If I may direct you to www.quartzlock.com and the online catalog, you will see specifications of the small H Masers.
We have both in use.
Nicholai Demidov's paper at EFTF 2012 showed real results of a number of active H maser's with drifts down to E-17 levels
One might ask when some benefit will be seen from all the trapped ion and optical clock work over the last 20 years ? cw a €160k AHM.

We used a NIST system here for months to look at our AHM drift / offset, but our maser was below the noise level of the NIST system, so we just had <E-12 results

Why AHM performance better, look at the physics package drawings in the catalog to see the multiple ovens, magnetic screens etc, but mostly AHM Q=40,000, where PHM Q=10,000.
Modern AHM have inbuilt autonomous autotuning to virtually illuminate drift.

Incidentally, an oral paper by a NIST or USNO in Switzerland at EFTF many years ago reminded us all that any greater performance will have to account for lunar phases, earth tides, sea level change 2 x day, local magnetic anomalies 9the least of one's worries and in any event, what is the application / relevance of these levels of performance. of course the advancement of knowledge is one, but hugely expensive.

Open  question: We regularly measure stability noise floors to E-17 levels. What other parameter can be measured with greater resolution ?

Clive Green G3OPX/MM 

Clive Green
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Quartzlock
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