[time-nuts] Re: Creating a D.I.Y Rubidium Atomic Clock
Bob Camp
kb8tq at n1k.org
Thu Jun 8 00:03:40 UTC 2023
Hi
The obscure footnote to much of this is that each cell is not always âpureâ
this or that. There are a range of issues that come up. You add buffer gas
of this or that type to correct for these issues. Just whatâs on that list â¦. itâs
been to many decades since I was into this â¦.
Bob
> On Jun 7, 2023, at 6:37 PM, Ed Marciniak via time-nuts <time-nuts at lists.febo.com> wrote:
>
> 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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