[time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock

[Ed Marciniak]

This might be of interest:

https://apps.dtic.mil/sti/pdfs/ADA627237.pdf
________________________________
From: Ed Marciniak <ed at nb0m.org>
Sent: Wednesday, June 7, 2023 5:37:16 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Cc: Stephen C. Menasian <menasian at ptd.net>
Subject: Re: [time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock

At least one implementation of rubidium clocks I've seen use a lamp, filter and resonance cell.

The filter had rubidium 85, the lamp and resonance cell had rubidium 87 or possibly a natural isotopic mix, likely with the lamp being natural rubidium isotopic abundance.

I suspect the higher quality ones had resonance cells with isotopically enriched rubidium 87.

Increased signal to noise ratio would allow lower lamp power, and potentially both lower light shift, and longer lifetimes on components.
________________________________
From: Stephen C. Menasian via time-nuts <time-nuts at lists.febo.com>
Sent: Wednesday, June 7, 2023 4:03:24 PM
To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
Cc: Stephen C. Menasian <menasian at ptd.net>
Subject: [time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock

I would suspect that indium is not suitable. The easiest elements to pump
optically are the alkali metals, due to their strong D lines which allow
the ground state atoms to absorb the appropriate radiation strongly,
thus, enabling the optical pumping effect.

On Wed, 7 Jun 2023 22:37:42
+0200 Marek Doršic via time-nuts <time-nuts at lists.febo.com> wrote:

> Certainly interesting topic. Rb provides a safe approach. However, I am
> curious to know if anyone has explored the possibility of using other
> elements, specifically Indium?
>
>    .md
>
> > On 7 Jun 2023, at 20:37, djl via time-nuts <time-nuts at lists.febo.com>
> > wrote:
> >
> > The Rb capsules are available on ebay, eg:  124012486501
> > the classblowing part is done?
> >
> > On 2023-06-07 07:50, Richard (Rick) Karlquist via time-nuts wrote:
> >> On 6/7/2023 5:03 AM, Stephen C. Menasian via time-nuts wrote:
> >>> 1) some pure Rb87
> >>> 2) a glass blowing setup (and some skill)
> >>> 3) A selection of inert gasses (at least including Ar)
> >>> 4) Light source (Rb discharge was used then with a circular
> >>> polarizer;
> >> At HP we had really skilled glass blowers, with specific experience
> >> in making Rb glassware.  We had to use an exotic grade of glass that
> >> was only one step removed from fused quartz.  It had a part number
> >> that I don't remember.  Very difficult to work with.
> >> The Rb lamp (one of three pieces of glassware) is very tricky to work
> >> with.  We used a resonant coil driven at 95 MHz at several watts.
> >> The trick is to "strike" the plasma and make the lamp light up;
> >> you can at least see visible light when that happens. I spent a
> >> lot of time fooling with it.  We never got it to work as
> >> well as the 5065 lamp.
> >> BTW, one of the Rb isotopes is slightly radioactive.  Might be
> >> hard to get as a hobbyist due to regulations.  The physicist I
> >> sat next to had a tank of it illegally stored in his cubicle.
> >> Rick
> >> N6RK
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> >
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