[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
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