[tvb]

Cesium beam atomic clocks are available on the surplus market, though not nearly as common or as cheap as Rubidium. The clock in the photo is model hp 5071A and I got it on eBay 20 years ago. The tube will last on the order of 7 to 20 years with continuous use, depending on which type of tube is installed.

This was one of the atomic clocks I used for the time dilation / relativity experiment linked at the bottom of the page.

[mikewarot]

I loved that story back then... with the advent of optical lattice clocks, and smaller sources, etc... have you done an update to the experiment?

[tvb]

Yes, the original Mt Rainier experiment in 2005 caught the attention of Stephen Hawking and I was asked to repeat the experiment for his PBS/BBC TV series in 2016. It was mid-winter up here in PNW so we used Mt Lemmon in Arizona instead:

http://www.leapsecond.com/great2016a/

And in 2018 I was asked to be part of a "time travel" episode on a History channel show. We used Palomar Mountain in California:

http://www.leapsecond.com/great2018a/

Each experiment was a little different; different combination of clocks, different audience, different mountain, different elevations, different latitude, etc.

[enjeyw]

Just been going through your blog, and I'm in love with your Synchronome clock, which begs the question (apologies if this is answered somewhere):

Of all the clocks you own, what's your favourite and why?