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

Bob Camp lists at rtty.us
Sun May 5 19:05:17 EDT 2013


There were a number of trapped ion papers back in the 70's and 80's. The NIST effort to transition from Cs to an ion standard was well underway by the mid 1980's. 


On May 5, 2013, at 5:49 PM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> 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:
> http://tf.nist.gov/general/pdf/910.pdf
> 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...
> Cheers,
> Magnus
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