[time-nuts] vs Hg ion? Re: GPS clock stabilitiy, Rb vs Cs

Magnus Danielson magnus at rubidium.dyndns.org
Sun May 5 17:49:25 EDT 2013

Hi Tom,

On 05/05/2013 11:33 PM, Tom Knox wrote:
> The idea of a Mercury Ion clocks started about 2000 and from about 2005 until recently has held the title of worlds most accurate clock.
> Approx 1 sec per 1.6 billion years the last I heard. At the heart is a single trapped mercury atom. Jim Bergquist at NIST was one of those that lead the development.
> This link has the basics: http://tf.nist.gov/general/pdf/1957.pdf.   I want two.

The history is older than that. A quick review of the early history is 
available here:

First detection of the transition was in 1973.
Len Cutlers first article on the topic (as referenced in above article) 
was back in 1981.

I have all the Hg-199 and Hg-202 I need for a few clocks, but in it's 
natural mixture. Don't feel like building a separation facility...


More information about the time-nuts mailing list