[time-nuts] Home built cesium clocks???
stijena at tapko.de
Sat Jun 28 15:12:16 EDT 2008
Microwave components are now cheap and easy to fabricate (thanks to
millions of GSMs GPSs and sat receivers).
Optical pumping/detection is difficult because optical frequencies
(hundreds of THz) have to be accurate and stable within 100khz (1
MHz at worst).
Cesium itself is also difficult part: It has to be extremely pure (N6
or better), and filling it without contamination....could be tricky.
At 17:14 28.6.2008, you wrote:
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Home built cesium clocks???
>Date: Sun, 29 Jun 2008 01:52:36 +1200
>Message-ID: <48664224.5070004 at xtra.co.nz>
> > swingbyte wrote:
> > > G'day fellow time-nuts.
> > >
> > > I was just going through some old projects and found my old home-made
> > > mass spectrometer. This was a project based on a design from either
> > > Scientific American or The Amateur Scientist back in the '60s. I was
> > > wondering if anyone here had heard of a similar project for a cesium
> > > clock? Although my home built mass-spec wasn't in the same league as a
> > > bought one, it did work and did get me a HD in physics! How hard is it
> > > to make a cesium clock? Just thinking about it and wondering what is
> > > actually inside the physics package.
> > >
> > >
> > > Tim.
> > >
> > >
> > Not a great deal:
> > A Caesium oven
> > A mechanical collimator for the Caesium beam
> > A pair of state selection magnets
> > A Caesium detector
> > A pair of Microwave cavities
>The microwave cavities should have a phase-stable distribution inbetween them
>and also a stable physical distance.
>Getter to capture stray atoms.
>The physical package should be magnetically shielded.
>Also, an ion pump.
>A variation would optically pump the cesium beam rather than using
>state selection magnets. I have not heard of any commercial cesiums using that
>technique, it is only used in a few lab cesiums.
>Masspectrometers seems to be the most popular detection method too, but
>optical detection is again used in a few lab cesiums.
>The physical package is along with the RF chain the most problematic parts.
>The rest is no big magic, but needs to be done with care.
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