[time-nuts] Nuclear transition for time reference - Nature 5-May, 2016, vol 533

[Attila Kinali]

On Mon, 23 May 2016 11:49:37 -0500
David Witten <wittend at wwrinc.com> wrote:

> My knowledge in this area is superficial.  But I wondered if anyone in this
> group had a reaction to the 5-May issue of nature that includes a 'News and
> Views' piece and a formal article reporting the detection by Von der Wense
> et al. of the 229m Thorium nuclear transition that is hoped to have utility
> in time-related metrology applications?
> 
> The key point seems to be that since nuclear transitions of this sort
>  involve shifts among excited states by quarks, which are governed by the
> strong force, many of the electromagnetic perturbations of clocks governed
> by electromagnetic force are eliminated.  (I think.)

Not only that. Because the nucleus is shielded by the electronic shell
from other atoms it's also less disturbed by anything close by.
While our current clocks all measure the hyperfine splitting (aka interaction
of the electron orbit angular momentum with the nuclear spin) of the
outermost electron, which is the one that gets hit first if anything in
the vincinity of the atom happens.

One of the problems seems to be, that the transistion is either very narrow,
or not where people expect it. This experiment (if the conclusions are
correct) narrowed down the range where the transition should be.
It's still far from actually detecting the transition, but at least it's
a good step forward.


			Attila Kinali
-- 
Reading can seriously damage your ignorance.
		-- unknown