Hi > On Nov 1, 2014, at 2:35 PM, Jim Lux <[email protected]> wrote: > > On 11/1/14, 11:05 AM, Magnus Danielson wrote: >> Jim, >> >>> However, if you were happy with "lab grade" construction, and you have >>> the Kurt Lesker and Duniway catalogs as bedside reading, I think you'd >>> have a chance. >> >> Yes. I guess a bit of baking out the build is also to be recommended. >> I guess most of us don't do vacuum in our labs, so there is a challenge >> in itself, as there is many beginners mistakes to be done there. > > > I haven't done high vacuum in quite a few years, but it is fascinating and > frustrating. These days, quite a bit of surplus gear is out there that does > make life easier (e.g. turbo molecular pumps). A Hg Ion system isn't real > huge, and doesn't have a big gas load, so a straightforward LN2 sorption pump > would probably work as a batch mode(e.g. a bunch of the right material, > plunged into a LN bath, and it the gas molecules just stick right to the > material.. ) > > >> >>> The ion trap and such is a fairly straightforward thing, from what I >>> understand: you need the usual vacuum pumps and such to build one. If >>> you don't want it to run for years without servicing, then issues of the >>> mercury content are less important. >>> (BTW, the space clock uses thermal dissociation of HgO to get the >>> mercury) >> >> Have tou cared to get the right isotope or do you use the natural >> abundance spreading? Hg-199 has an abundance of 16,87%. > > Interesting, I don't know if they go out and sort it, or if they set up the > system so that it's basically a mass spec, and the wrong isotope doesn't make > it through the quadrupole filter.
Don’t in any way discount the amount of effort in getting that filter to work “right”. > I'll bet the latter. No matter how good your offline enrichment process is, > there will always be some other "stuff" in there. For all I know, the > actual ion trap is specific to the mass of the ions. > > > >> >>> The PMT is an off the shelf thing. Check out the amateur built fusion >>> reactor (fusor) websites on where to get PMTs and amplifiers (they're >>> used behind a scintillator) >> >> Ah yes. Got a NaI(Tl) scintilator with about 1 cm copper filter and a >> matching PMT. No amp thought, but then again, I do not know what I >> should measure with it. :) > > You can measure radiation from common household objects like bananas > >> >>> The 40 GHz stuff these days is not nearly as exotic as it used to be. >>> The challenge might be test equipment when you're debugging your 40 GHz >>> synthesis chain. >> >> I was thinking the same, especially when consider optical clocks, then >> 40 GHz isn't as esoteric. Can you get this all done with 40 GHz as your “top” frequency? >> Traditional cesiums and rubidiums use a pair >> of synthesized frequencies being then sent into a step-recover diode >> inside a tuned cavity which then does the mixing and selects the right >> combination. > > Same scheme might work here. Next time I'm talking to one of the DSAC folks, > I'll ask how they do the synthesis chain. > >> >>> I don't think it would be *easy*, but I think doable, and nothing in the >>> system is particularly expensive or that exotic. It's sort of like >>> telescope building.. The raw materials to make a 18" reflector telescope >>> aren't all that expensive, nor is there some secret sauce: it's just >>> time to grind the mirror (and recover from mistakes) and build the >>> system. >> >> Would be a fun project to do, things to be learned. >> > > For when you get tired of counting femtoseconds.. Then you need to build a second one to check the first one with. Bob > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
