On Sat, 14 Mar 2020 14:50:45 -0400 Bob kb8tq <kb...@n1k.org> wrote: > A brand new 5071 with that tube appears to be over $90,000 these days. Based > on > running one for a lot of years, After about 6 years of operation, you will be > sending > it back for a new tube. By the time the unit is back in your lab, the refit > will cost > roughly half the price the whole unit cost new …. gulp …..
At those prices, I'd rather go for a µQuans or SDS Rb clock. Those don't lose atoms like the Cs beam does and thus don't need a refill. Their lifetime is more likely in the decades than just a few years. Weakest link, as far as I know, are the lasers. And yes, after the second, at latest after the third Cs tube, these Rb devices are cheaper. And they are as much a primary standard as the 5071 is. On Sat, 14 Mar 2020 13:57:21 -0700 Hal Murray <hmur...@megapathdsl.net> wrote: > Can the physics-nuts calculate the Rb frequency relative to Cs? Theoretically yes, practically no. While we "know" exactly what each electron in the atom is doing and how it interacts with each other electron and the nucleus, there are so many of them that there is no closed form solution (c.f. three/many body problem). As far as I am aware of, nobody has even done a complete numerical model. So all the calculations we have today are approximations that bunch most if not all inner electrons together and approximate them by an average field. > What's missing on a gas cell? Is the problem theory or implementation? Both. For one, you cannot control all parameters during production well enough that a calulated shift would be any more accurate. For another, there are quite a few shifts in the system, from buffer gas shift (dependent on exact composition) to light shift to RF power shift to RF field gradient shift to temperature gradient shift to ..... Some of them nobody thought of until a PhD student tried to figure out what the next limiting factor was. If you would try to make the system as well characterizable as a Cs beam standard, then you would end up with a product that is at least as expensive, if not more. If you want to know more, have a look at the publications, especially the dissertations, by the time/frequency lab at UniNE: https://www.unine.ch/ltf/home/publications.html They go into quite detailed analysis of what the different shifts are that are affecting the long term stability of Rb vapor cells. Attila Kinali -- <JaberWorky> The bad part of Zurich is where the degenerates throw DARK chocolate at you. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.