Re: [time-nuts] Cold Rubidium?

IEEE-UFFC recently posted some videos from IFCS/EFTF 2019, and there's one by muquans: https://www.youtube.com/watch?v=1eHhdNk50uE (for me, sound is extremely low in these... need to turn up volume to almost max) > ___ time-nuts mailing list --

Re: [time-nuts] Cold Rubidium over hyped?

Moin, On Fri, 8 Nov 2019 14:33:45 -0800 wrote: > Well I have been looking at the data in the > > https://www.researchgate.net/publication/325499937_A_portable_cold_87_Rb_ > atomic_clock_with_frequency_instability_at_one_day_in_the_10-15_range > > link and find that maybe they are

Re: [time-nuts] Cold Rubidium over hyped?

Hi > On Nov 8, 2019, at 11:18 PM, cdel...@juno.com wrote: > > The pressure sensitivity for a classic design can easily be eliminated. > > I'm pretty sure that the old Varian R20 cell was mostly immune. > > Either using the R20 design or stiffer convex ends in a modern design > would work. > >

Re: [time-nuts] Cold Rubidium over hyped?

Hi, On 2019-11-09 08:05, Poul-Henning Kamp wrote: > > In message , cdel...@juno.com writes: > > [long list of all the work to be done before the classical gas-cell Rb > improves materially] > > You are sort of making my point here Corby. > > It is not like people have not been improving

Re: [time-nuts] Cold Rubidium over hyped?

In message , cdel...@juno.com writes: [long list of all the work to be done before the classical gas-cell Rb improves materially] You are sort of making my point here Corby. It is not like people have not been improving the Rb-Gas-cell, but if you want to improve it an order of

Re: [time-nuts] Cold Rubidium over hyped?

On 11/8/19 5:38 PM, Magnus Danielson wrote: So, while hydrogen masers may work and large cell rubidiums can be cleaned up, eventually we come to the point where these new techniques will take over for many good reasons. Maybe one day we will have time-nuts with cold rubidium clocks and maybe

Re: [time-nuts] Cold Rubidium over hyped?

Hi, On 2019-11-09 01:07, Poul-Henning Kamp wrote: > > In message , cdel...@juno.com writes: > >> Just wonder if some 5065A can get so impressive that they don't just >> make a modern large/cool cell classic Rubidium with modern electronics >> technology! Certainly would be cheaper and

Re: [time-nuts] Cold Rubidium over hyped?

I think you are missing the key selling point of this device, namely it's long term stability and accuracy of a few parts in 10^15. From my point of view as a national timekeeper, this is much more useful than good short term stability. UTC reporting is at 5 day intervals so what the clock does at

Re: [time-nuts] Cold Rubidium?

Hi, On 2019-11-08 03:15, Hal Murray wrote: > p.bo...@xs4all.nl said: >> We were seriously considering the Muquans clock for a radio astronomy >> project. However, the company explained that the device has to be returned >> every 3 to 5 years for re-filling. Given the very remote location we

Re: [time-nuts] Cold Rubidium?

On 11/7/19 6:15 PM, Hal Murray wrote: p.bo...@xs4all.nl said: We were seriously considering the Muquans clock for a radio astronomy project. However, the company explained that the device has to be returned every 3 to 5 years for re-filling. Given the very remote location we were going to

Re: [time-nuts] Cold Rubidium?

Good questions, Hal. This reminds me of the HP Cesium Beam Tube useful life. The standard tube, at least, is such that it is unlikely to last long enough to completely use up the cesium. Then there is the rest of the instrument. My experience with the HP Rubidium units is that if you just

Re: [time-nuts] Cold Rubidium?

p.bo...@xs4all.nl said: > We were seriously considering the Muquans clock for a radio astronomy > project. However, the company explained that the device has to be returned > every 3 to 5 years for re-filling. Given the very remote location we were > going to put these in, that was out of the

Re: [time-nuts] Cold Rubidium?

Hi Attila, everyone, On 11/3/19 7:12 PM, Attila Kinali wrote: You do not need to replenish the Rb supply, as the Rb atoms do not get used up. They are free floating in vaccuum and get captured by the MOT. Thus, unlike the Cs beam's oven, which just spits the Cs atoms out, the MOT does not need

Re: [time-nuts] Cold Rubidium?

On Sun, Nov 3, 2019 at 7:04 PM Attila Kinali wrote: > Though, the cost is lower. Low enough that I would choose one of > these instead of buying a 5071. My google sleuthing indicates that they're selling it for about $347k:

Re: [time-nuts] Cold Rubidium?

On Sun, 03 Nov 2019 21:56:38 + "Poul-Henning Kamp" wrote: > Not _quite_ a DIY project yet, but certainly easier than a fountain... Not by much, though. In terms of infrastructure you need, you are pretty close to a fountain: Advanced laser system with multiple frequencyies locked to an

Re: [time-nuts] Cold Rubidium?

In message <20191103191220.eb7af29b45fdaf77f2fa4...@kinali.ch>, Attila Kinali writes: Not _quite_ a DIY project yet, but certainly easier than a fountain... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer

Re: [time-nuts] Cold Rubidium?

Moin, On Fri, 25 Oct 2019 09:32:59 -0600 "AC0XU (Jim)" wrote: > Does anyone have any experience/first hand knowledge of this Cold Rubidium > standard? > > https://spectradynamics.com/products/crb-clock/ > > The specs look very good. The mfr

Re: [time-nuts] Cold Rubidium?

Hi Rick, On 2019-10-26 21:04, Richard (Rick) Karlquist wrote: > The proverbial "dumb questions": > > Is there an actual refrigerator somewhere > in this gadget, or are the Rb atoms in a > room temperature vacuum and the laser cools > just the atoms.  It appears to be the latter. > Having done the

Re: [time-nuts] Cold Rubidium?

Hi, On 2019-10-27 10:12, Anders Wallin wrote: > This paper from the french group has some details > https://arxiv.org/pdf/1812.01658.pdf > they say it's a redesign of the previous version ( > https://journals.aps.org/pra/abstract/10.1103/PhysRevA.82.033436), but it > looks roughly the same.. >

Re: [time-nuts] Cold Rubidium?

This paper from the french group has some details https://arxiv.org/pdf/1812.01658.pdf they say it's a redesign of the previous version ( https://journals.aps.org/pra/abstract/10.1103/PhysRevA.82.033436), but it looks roughly the same.. page 2 of the datasheet shows the vacuum system and bulb:

Re: [time-nuts] Cold Rubidium?

In message , Dana Whitlow writes: >I can only answer one of your questions with any confidence, but I'd >suspect that the chamber walls are cooled a fair bit in addition to >being highly reflective. Why would you need to cool them any more than you need to cool them in a cesium

Re: [time-nuts] Cold Rubidium?

The atoms are laser cooled and held in a magneto-optical trap. It’s basically a short, one-way fountain. Cooling the microwave cavity would be useful for reducing the black body radiation shift, but without checking the numbers, this would not be so useful at the relatively low accuracy claimed

Re: [time-nuts] Cold Rubidium?

Hi If you look at the ADEV plot, there is some sort of bump out in the 1 to 2 days region. That would suggest it’s not 100% immune to the local environment…. The box is big enough that you *might* fit a chiller in it. If so, heat would need to be vented. I see no (obvious) vents or heatsinks.

Re: [time-nuts] Cold Rubidium?

The proverbial "dumb questions": Is there an actual refrigerator somewhere in this gadget, or are the Rb atoms in a room temperature vacuum and the laser cools just the atoms. It appears to be the latter. So the enclosure has low emissivity so it doesn't transfer too much heat to the atoms by

Re: [time-nuts] Cold Rubidium?

In message , Anders Wallin writes: So sort of a "one-way/drop" fountain really ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be

Re: [time-nuts] Cold Rubidium?

ptti2018: https://www.researchgate.net/publication/322920519_Long_term_frequency_instability_of_a_portable_cold_87Rb_atomic_clock ifcs2018: https://www.researchgate.net/publication/325499937_A_portable_cold_87_Rb_atomic_clock_with_frequency_instability_at_one_day_in_the_10-15_range this one is