Exact Rubidium frequency
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)
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 -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi Peter:
Yes, as far as I can tell all oscillators have an adjustment to allow changing
their frequency, including the C Filed adjustment on a Cesium standard. The
key difference is that with the Cesium standard, by definition, it does not
drift. So if you make a phase plot comparing any oscillator to say a timing
grade GPS receiver the shape will be parabolic or some higher polynomial. But
for a Cesium it will be a straight line.
The more modern Cesium standards have control loops that automatically set the
C Field and maintain it so do come very close to the plug and play idea. But
the first few generations of Cesium standards need to be tweaked on frequency.
The HP 5060 C Field adjustment is so coarse that a modern Rubidium standard is
more accurate.
http://www.prc68.com/I/5060A.html <- C Field step size near 1E-10 if you use
the smallest mark on the vernier of the 10 turn pot
http://www.prc68.com/I/FTS4060.shtml <- C field step size near 1E-14, 3 digit
thumb wheel.
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
Peter Vince wrote:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+brooke=pacific.net+brooke=pacific.net@febo.com
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 -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
From: Peter Vince pvince@theiet.org
Subject: [time-nuts] Exact Rubidium frequency
Date: Sun, 1 Jul 2007 00:11:34 +0100
Message-ID: <v04210100c2ac925eb18d@[10.0.0.3]>
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?
Please check this page out:
http://rubidium.dyndns.org/~magnus/physics/hyperfine/
6.834682610904324(4)(7) GHz is the best number I've got for Rubidium and
1.4204057517662(30) GHz is the best number I've got for Hydrogen.
I have provided references for those numbers.
The MathML stuff look like crap for me as I checked it but it used to be
alright.
Any normal Rubidium and Hydrogen clock is being pulled from actual numbers not
only by magnetic field but also wallshift and cavity shift for hydrogens and
in the Rubidium case by additional buffer gas pulling. The Hydrogen is being
examined by various sizes of bulbes in the same cavity as the wall shift
changes in a predictable form and this way its effect can be cancelled
numerically in a fashion which doesn't lend itself to a normal clock.
The very good Rubidium number comes of a Rubidium fontain in Paris. Rubidium is
a better atom for fontain clocks than Caesium. Far better actually. Cools down
better, so there's why.
Cheers,
Magnus