); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] > Frequency Standard Frequency Quotations - Apr 2007 > > > CESIUM > > 9,192,631,830 hz +/- 10 hz. 1 Feb 1957. Atomic Clocks. Harold Lyons. NBS. > Quotes L. Essen and J. V. L. Parry NPS Cesium. > > 9,192,631,840 hz. 1 Dec 1958. IRE Transaction On Instrumentation. The > Ammonia Maser As An Atomic Frequency And Time Standard. R. C. Mockler, J. > Barnes, R. Beehler, H. Salazar, and L. Fey > > 9,192,631,735 hz +/- 10 hz. 12 Apr 1959. Hyperfine Transitions In > Rubidium-87 Vapor. E. C. Beaty, P. L. Bender, and A. I. Chi. NBS. > > 9,192,631,770 hz +/- 20 hz. 1Sep 1960. Atomic Beam Frequency Standards. R. > C. Mocker, R. E. Beehler, and C.S. Snider. Quotes Reference 21, by W. > Markowitz, R. G. Hall, L. Essen, and J. V. L. Parry. Frequency of Cesium In > Terms Of Ephemeris Time. Phys. Rev. Lett. Vol 1 PP 105-107 Aug 1958. > 9,192,631,770 hz. 1967. Thirteenth General Conference on Weights and > Measures defined the second of atomic time in the International System of > Units (SI) as the duration of 9,192,631,770 periods of the radiation > corresponding to the transition between the two hyperfine levels of the > ground state of the caesium-133 atom. > > HYDROGEN > > 1,420,405,730 hz +/- 50 hz. 1 Jan 1962. Atomic Beam Frequency Standards. > Richard C. Mocker. NBS. Adv. Electr. Phys. > > 1,420,405,751.80 hz +/- 0.03 hz. 1963. Crampton, S. D. Kleppner, N. F. > Ramsey. Hyperfine Separation Of Ground State Hydrogen. Letters 11, 338 > > 1,420,405,751.7860 hz +/- 0.0046 hz. 1 Feb 1966. Beehler, Halford, Harrach, > Allan, Glaze, Snider, Barnes, Vesot, Peter, Vanier, Cutler, and Bodily. An > Intercomparison Of Atomic Frequency Standards. Proc IEEE. Also quotes the > following measurements: > 1,420,405,751.825 hz +/- 0.02 hz. 1963. Varian-Naval Obs > 1,420,405,751.800 hz +/- 0.028 hz. 1963. Harvard-Naval Obs > 1,420,405,751.778 hz +/- 0.016 hz. 1964. Varian-HP > 1,420,405,751.785 hz +/- 0.016 hz. 1964. Varian-L SRH > 1,420,405,751.781 hz +/- 0.016 hz. 1963. NASA-GSFC > 1,420,405,751.7860 hz +/- 0.0046 hz. 1965. Varian-HP > > 1,420,405,751.768 hz +/- 0.002 hz. 1970. Measurement Of The Unperturbed > Hydrogen Hyperfine Transition Frequency. Hellwig, Allan, Glaze, Vessot, > Levine, Zitewitz, Peters. IEEE CPEM Conf. Also quotes the following > measurements: > 1,420,405,751.7691 hz +/- 0.0024 hz. > 1,420,405,751.7667 hz +/- 0.0018 hz. > > > 1,420,405,751.7864 hz +/- 0.0017 hz. Dec 1966. An Intercomparison Of > Hydrogen And Cesium Frequency Standards. R. Vessot, H. Peters, J. Vanier, > R. Beehler, D. Halford, R. Harrach, D. Allan, D. Glaze, C. Snider, J. Barnes, > L. Cutler, and L. Bodily. IEEE Transaction On Instrumentation And > Measurements. Vol IM 15 #4 > > 1,420,405,751.768 hz +/- 0.002 hz. 1970. Measurement Of The Unperturbed > Hydrogen Hyperfine Transition Frequency. Hellwig, Allan, Glaze, Vessot, > Levine, Zitewitz, Peters. IEEE CPEM Conf. Also quotes the following > measurements: > 1,420,405,751.7691 hz +/- 0.0024 hz. > 1,420,405,751.7667 hz +/- 0.0018 hz. > > 1,420,405,751.77 hz. 31 May 1978. A Small Passively Operated Hydrogen > Maser. NBS. D. A. Howe, F. L. Walls, Howard E. Bell, and Helmut Hellwig. > Proc 1978 Freq Contr Symp. > > > RUBIDIUM > > 6,834,682,608 hz +/- 7 hz. 12 Apr 1959. Hyperfine Transitions In > Rubidium-87 Vapor. E. C. Beaty, P. L. Bender, and A. I. Chi. NBS. > > 6,834,682,614 hz +/- 3 hz. 9 Sep 1963. R. C. Mockler. Atomic Frequency > And Time Interval Standards. Proc XIV Gen Assem URSI. Quoting Penselin, > Moran, and Cohen 1961. > > 6,834,683,405 hz. 6 Apr 1964. R. J. Carpenter. A Portable Rubidium-Vapor > Frequency Standard. NBS Tech Note 235. > > 6,834,682,608 hz +/- 7 hz. 29 June 1965. P. L. Bender. Patent 3,192,472 > Alkali Vapor Frequency Standard Using Optical Pumping. > > >
Peter Vince wrote: > Everyone on the 'net agrees on the frequency of the Caesium > oscillation, but the precise frequency quoted for Rubidium varies by > a few Hz :-( Now I realise that you can make it anything you like > (within reason) by altering the magnetic field, and perhaps different > sources quote different figures which are more or less easy to > synthesise? > > On the (USA) NIST web-page > (http://tf.nist.gov/general/enc-re.htm#rubidiumoscillator) they quote > 6,834,682,608 Hz, but the (German) PTB (on > http://www.ptb.de/en/org/4/44/441/info2_e.htm) give 6,384,682,612.8 > Hz, and the (British) NPL quotes 6,834,682,610.904 324 Hz in a > powerpoint presentation > http://www.npl.co.uk/time/club/meeting1/secondaryrepsec.pdf > (admittedly for a Rubidium fountain). > > I have also seen the frequency of a Hydrogen Maser given as both > 1,420,405,751 Hz and ...752 Hz. I would be very surprised if the > frequency was an exact whole number of Hertz different from Caesium, > so perhaps this is just rounded for convenience as again it can be > steered to anywhere you like? > > Would anyone care to comment on this differences please? > > Thank you, > > Peter Vince (G8ZZR, London) > > _______________________________________________ > 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.
