[time-nuts] Rubidium standard

Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Nov 23 22:38:14 UTC 2009


Both the lamp and the absorption cell contain rubidium.
The rubidium in the lamp is slowly absorbed by the glass container.
The rubidim in the absorption cell is mixed with a buffer gas and 
presumably has a much lower rate of absorption by the cell walls.
The rubidium lamp becomes unusable due to rubidium absorption long 
before the absorption cell rubidium is depleted.
This lamp wear out mechanism is avoided if one uses laser interrogation 
of the absorption cell.

Bruce

Alan Melia wrote:
> They probably dont want the little rascals bumping into one-another and
> broadening
> the resonance line :-))
> Alan G3NYK
> ----- Original Message -----
> From: "Mike S"<mikes at flatsurface.com>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Monday, November 23, 2009 9:10 PM
> Subject: Re: [time-nuts] Rubidium standard
>
>
>    
>> At 03:24 PM 11/23/2009, Poul-Henning Kamp wrote...
>>
>>      
>>> There are no "rubidium crystals" involved.
>>>        
>> Next you'll try and tell us that you can't make a clock run backwards
>> by using dilithium crystals, and making it warp time.
>>
>> My understanding is that the Rb gets absorbed into the glass envelope,
>> so that eventually there isn't enough to provide proper operation. Rb
>> isn't that expensive (you can buy 1 g for $100 at retail -
>> http://elementsales.com/pl_element_grp1.htm ), so I'm not clear on why
>> they don't just put more than ~0.001 g in to begin with.
>>
>> www.spectratime.com/product_downloads/life_mtbf.pdf
>>
>>
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