[time-nuts] Helium and MEMS oscillators don;t mix well
Richard (Rick) Karlquist
richard at karlquist.com
Wed Oct 31 19:21:32 EDT 2018
On 10/31/2018 3:51 PM, Poul-Henning Kamp wrote:
> In message <55d57bbe-ec9b-dc3c-f5d1-fdd21338f344 at karlquist.com>, "Richard (Rick
> ) Karlquist" writes:
>> This reminds me of a Jack Kusters (of HP fame) anecdote.
>> At which point Jack pointed out
>> that in that case, it was clear than they had a radon
>> incursion in their facility.
> I have a hard time beliving radon was a relevant failure mechanism
> for "telco-class" Rb units, things would literally glow in the dark
> long before the Rb concentration became a problem.
> It is true that Radon is a small atom, but it is 50% larger than
> Helium and that is a big handical when diffusing.
> More importantly, Radon decays in a matter of days, much faster
> than it would "evaporate" out again, and it leaves a tell-tale
> signature of lead atoms behind from the decay.
> I find it far more likely that their problem were molecular hydrogen,
> which is even smaller than Helium atoms, and present in copious
> amounts near any rechargeable battery and a fair number of industrial
According to Jack, radon emits alpha particles, AKA helium nuclei.
These capture stray electrons and become helium atoms. So the
presence of helium is a marker for radon. The fact that the half
life is a few days supports this hypothesis. At least that is what
Jack told me.
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