[time-nuts] You can build a fountain from the things you find at home...
brent.evers at gmail.com
Tue Sep 27 19:39:14 UTC 2011
Well, this is supposed to be a list about amateur precision
timekeeping, so at the risk of looking like a total idiot, I'll take
the bait and throw out a few questions.
First - I've only been on this list for about 6 months, and am only
just beginning to get my head around some of the concepts regarding
clocks, measurements and the transfer of time. I think its especially
"timely" to be learning about this given the events at CERN - and I'm
learning a lot from that too.
That said, I've wondered how one as an individual/amateur might go
about building an atomic clock. I've got another interest in
machining and have a barn full of heavy cnc iron out back (old stuff,
but good stuff - none less than 7000 ponds) that I'm slowly putting
So at its most basic, I'm wondering what type of clock would make the
most sense to consider - cesium fountain, or hydrogen maser? I
haven't done enough research in either to know which modes they
oscillate the cavity in, but presumably, the cavity for the cesium is
going to be a lot smaller just based on the oscillation frequency
alone, so there is some cost benefit there.
What about material availability? I don't know what form of cesium or
hydrogen are needed, but I'm assuming that hydrogen is more available
with less hassle?
It seems like there are a few simple things that could be done to
cheaply gain on the stability curve. I live in an area with a high
water table (right next the the chesapeake bay). Why not drill a
shallow well - 20ft?? to submerge the cavity and gain the thermal
stability of the well? I'm from the subsea world, so putting
something 20 feet down is nothing (most of my stuff goes to 6000m).
Last - I've got a good friend that works at Jefferson Lab, involved in
niobium deposition to get their cavity Q's up. What's the feasibility
of an amateur doing something like that to improve cavity Q.
Again - I apologize for my complete lack of knowledge on the subject,
but these are just some of the ideas I've had bouncing around my head
for how this might be done to make a pretty good clock on a pretty
Last - I hope you got to visit the USNO library - its definitely on of
the coolest places to see for a scientist/engineer in DC.
On Tue, Sep 27, 2011 at 3:01 PM, Robert Darlington
<rdarlington at gmail.com> wrote:
> So I find that somewhat surprising (Aluminum as a material for UHV systems)
> because they outgas water -for months. Anodized aluminum is especially
> bad! Did they make any suggestions on cleaning the oxide off before pumping
> down and baking?
> -Bob (machinist and vacuum nut)
> On Tue, Sep 27, 2011 at 12:56 PM, Poul-Henning Kamp <phk at phk.freebsd.dk>wrote:
>> I just finished my Colloquium on leap-seconds at the USNO, and afterwards
>> had lunch with Demitriou Matsakis and one of his Fountain building
>> Remembering a previous discussion on the topic here, I asked if building
>> a fountain would be a feasible amateur project.
>> The answer is "yes, if you have enough money".
>> The shared wisdom was that you want to build your vacuum vessel out
>> of aluminium, which in addition to being a-magnetic also makes it
>> possible to bolt the windows in, rather than mounting them by
>> welding and that rubidium is a better target atom than cesium.
>> Gentlemen, start your lathes...
>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG | TCP/IP since RFC 956
>> FreeBSD committer | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by incompetence.
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