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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: OT: Atomic nucleus excited with laser: a breakthrough after
 decades
Date: Wed, 8 May 2024 01:44:10 +1000
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On 8/05/2024 12:41 am, John Larkin wrote:
> On Tue, 7 May 2024 14:35:12 +0100, Martin Brown
> <'''newspam'''@nonad.co.uk> wrote:
> 
>> On 07/05/2024 06:06, Jan Panteltje wrote:
>>> Atomic nucleus excited with laser: a breakthrough after decades
>>>    https://www.sciencedaily.com/releases/2024/04/240429103045.htm
>>>     The 'thorium transition', which has been sought after for decades,
>>>     has now been excited for the first time with lasers.
>>>     This paves the way for revolutionary high precision technologies, including nuclear clocks
>>
>> I wonder what the Q value for stimulated nuclear emission is?
> 
> "the correct energy of the thorium transition was hit exactly, the
> thorium nuclei delivered a clear signal for the first time. "
> 
> I wonder what that signal was.

Presumably the thorium nucleus absorbs the photon, then remits it when 
it decays back to the ground state, presumably not in the original 
direction.

The life-time of the excited state is 630sec when the thorium atoms are 
presented in a CaF2 crystal. It you hit the crystal briefly with 
precisely the right frequency, then observed a slowly decaying 
fluorescent signal at the same wavelength, you'd have a clear enough 
signal (though not all that much of it).

In fact they gradually stepped up the exciting beam wavelength from 
148.2 to 150.3 nm.,and observed a fluorescence peak at around 148.38 nm.

The observed central wavelength of the nuclear transition amounted to 
148.3821(5) nm, equivalent to a transition energy of 8.35574(3) eV, 
which was consistent with the 1 σ-uncertainty of the value reported in 
radiative-decay experiments but with 800-fold improved precision.

The implication is that their excitation wavelength wasn't all that 
precise either and will need to be made even more precise for nuclear 
clock work.

I wonder if they could use it to get Doppler shifts from continental drift?

-- 
Bill Sloman, Sydney