[time-nuts] Home built Ammonia cell std !! / Home built cesiumclocks???

Magnus Danielson magnus at rubidium.dyndns.org
Sun Jun 29 17:26:58 UTC 2008


From: "John Franke" <jmfranke at cox.net>
Subject: Re: [time-nuts] Home built Ammonia cell std !! / Home built cesiumclocks???
Date: Sun, 29 Jun 2008 12:20:28 -0400
Message-ID: <001e01c8da04$0b83a3c0$1e89a662 at youre7075dc078>

> Now that is something I am interested in doing.  I finally secured use of a 
> diffusion pump at a local university and expect to be making my first sealed 
> all-glass absorption cells this fall.  The ammonia pressure needs to be 
> around 8-10 microns.  I will be trying for a double pass cell giving a pass 
> length between 10 and 12 feet.  The first ammonia atomic clock used a path 
> length of 33 feet.  The cell was made from waveguide and did not hold a 
> charge due to leaks or the ammonia reacting with the gold plated waveguide. 
> I believe the best ammonia based standard was only good to 10 ^ -8 in 
> frequency stability.

More like 5E-11 both in cavity pulling and collision effects. Cavity
pulling was reduced in 1961 by means of automatic cavity tuning.

Recall that you do state-selection on the ammonia beam. An electrostatic
quadrapole configuration was used. Just like a Hydrogen maser.

Cheers,
Magnus




More information about the Time-nuts_lists.febo.com mailing list