Good questions. The one that bothers me is the magnetic levitation required to compare the standard to anything. You can't put other materials inside the vacuum bell with the standard. I looked up the paper, but it's behind a $40 pay-wall.
Electromagnets will levitate permanent magnets, but the effect is not stable, with the free magnet sliding out of the field. Diamagnetic materials will be stable, but the effect is so weak it would require superconducting electromagnets. Quartz, as it happens, is diamagnetic. Now the problem is to apply identical levitation to dissimilar materials. This would seem to require identical superconducting magnets and identical levitated platforms. Identical currents can flow in the levitating magnets simply by connecting them in series. In order for the platforms to be identically levitated, they have to be an identical distance from the levitating magnet. Measuring that to the required precision could be a challenge. Machining physical parts can be done to 10 E-6. That's not enough, so the mechanism will require calibration. I suppose they could compare it to the present platinum standard. Then there's the question of calibration interval, and what to use as the standard. Counting oscillations of atoms would be so much easier. I think Rick's three points make this a non-starter. It's a case of experts in metrology not having enough expertise in quarts resonators. In answer to why they can't use 10 grams, the comparison has to be 100 times more accurate than that for 1000 grams. Hope I haven't strayed too far off topic, and wasted my time. Bill Hawkins -----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Richard (Rick) Karlquist Sent: Sunday, April 22, 2018 4:11 PM To: Discussion of precise time and frequency measurement; Bob kb8tq Subject: Re: [time-nuts] Better quartz crystals with single isotope ? On 4/22/2018 10:20 AM, Bob kb8tq wrote: >> Do we know anybody in the quartz business who needs a really cool >> research project ? > > You could put it on the list with the 1 Kg quartz resonator proposal ... > > https://tf.nist.gov/general/pdf/2638.pdf > <https://tf.nist.gov/general/pdf/2638.pdf> > > Also an offshoot of people thinking about the implications of all this as it relates to resonators. > > > Bob > The cited article "must be true" because of its authors, I guess, but it makes no sense to me. They seem to be assuming that the resonant frequency is inversely proportional to mass? We all know three things: 1. Frequency is inversely proportional to thickness. Not mass. 2. Frequency aging is affected by stress relaxation in well built resonators. The old idea that mass is gradually evaporating from the resonator to the enclosure (glass enclosures) or mass is gradually evaporating from the enclosure (metal enclosures) to depositing on the resonator is simply obsolete in terms of current technology. Thus again frequency is not a proxy for mass. 3. Resonators can "jump" in frequency without jumping in mass. Given these facts, I am lost as how this is supposed to work. Surely, the authors are well aware of the 3 items above. Also, why does the resonator have to be a whole kilogram anyway. If it weighed exactly 10 grams, couldn't you still compare it to a kilogram using 100:1 leverage? Can anyone straighten me out? Rick _______________________________________________ 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.
