[time-nuts] 50th Anniversary of the Atomic Clock

[Tom Van Baak]

Brooke,

My understanding is that NBS's early cesium work
got sidetracked due to the move from Maryland to
Colorado about that time. That's partly why NPL
gets the limelight.

The other reason is that the NPL cesium standard
operated as a continuous production-quality atomic
*clock*; while other earlier efforts were more like
research atomic *frequency* standards.

As you know keeping atomic time, whether as
a professional or as an amateur, is much harder
than keeping atomic frequency.

This was necessary since it took a 3-year run
to compare the Cs second with the ET second.
The final value of 9 192 631 770 was announced
in 1958. The original paper is at:

http://www.leapsecond.com/history/1958-PhysRev-v1-n3-Markowitz-Hall-Essen-Pa
rry.pdf

Yes, my guess is FTS did the first uP cesium;
HP joined the trend with the 5071A in 1990 or
so; but the all the old 506x models were all
non-computerized. I don't have a date for the
4060 but Michael Garvey's two patents are
from the 80's. See:

Autolock for resonators for frequency standards
R M Garvey
February 12, 1985
http://www.leapsecond.com/patent/US4499433.pdf

Microwave power level stabilizing circuit for cesium beam frequency
standards
David W. Allan & R M Garvey
May 25, 1982
http://www.leapsecond.com/patent/US4331933.pdf

/tvb

----- Original Message -----
From: "Brooke Clarke" <brooke at pacific.net>
To: "Tom Van Baak" <tvb at leapsecond.com>; "Discussion of precise time and
frequency measurement" <time-nuts at febo.com>
Sent: Monday, August 01, 2005 11:20
Subject: Re: [time-nuts] 50th Anniversary of the Atomic Clock


> Hi Tom:
>
> I've been reading some of these articles and notice that NBS started
> work with Cesium standards around 1948, yet it was the Essen standard at
> NPL in the UK that seems to be the important one.  I take it that this
> means that Essen's standard worked much better, but how was his
> different from the NBS standard?
>
> On a time line where does the FTS4060 standard fit relative to the HP
> offerings?  Was it the first microcontroller based Cesium standard?
>
> Have Fun,
>
> Brooke Clarke, N6GCE
> PS I had the top lid off my 5060A for a photo opportunity and must say
> it's really a work of art.
>
> Tom Van Baak wrote:
>
> > 2005 is the 100th anniversary of Einstein's first set
> > of famous papers, including the one on relativity.
> > This has received a fair amount of press this year.
> >
> > Less well known is that 2005 is also considered
> > the 50th anniversary of the atomic clock. Here is
> > a collection of papers and links if you're short of
> > summer reading material:
> >
> >
> > 50th Anniversary of the First Accurate Cesium Atomic Clock
> > (Symmetricom PR)
> >
http://www.imakenews.com/eletra/mod_print_view.cfm?this_id=432361&u=symmttm
> >
> > Louis Essen - Famous for a Second
> > by his son, Ray Essen
> > http://www.btinternet.com/~time.lord/
> >
> > History of Atomic Frequency Standards-
> > A Trip Through 20th Century Physics
> > by Arthur O. McCoubrey
> > http://www.ieee-uffc.org/fcmain.asp?page=mccoubrey
> >
> > http://www.leapsecond.com/history/
> > Time Scales (the original 1968 Metrologia article where
> > Louis Essen documents the difficulties coordinating
> > astronomical time and atomic time)
> >
> > Einstein Year 2005 - Celebrating Time
> > http://www.npl.co.uk/einstein_year/
> >
> > Science Museum | Atomic clocks | Louis Essen
> > http://www.sciencemuseum.org.uk/on-line/atomclocks/page1.asp
> >
> > Frequency of Cesium in Terms of Ephemeris Time
> > by W. Markowitz and R. Glenn Hall, USNO
> > by L. Essen and J. V. L. Parry, NPL
> > http://prola.aps.org/abstract/PRL/v1/i3/p105_1
> >
> > Fifty years of atomic clocks
> > http://physicsweb.org/articles/world/18/5/2/1
> >
> > Metromnia Issue 18 - Spring 2005 - Einstein
> > http://www.npl.co.uk/publications/metromnia/issue18/
> >
> > The History of Frequency Control and Modern Time Keeping
> > compiled by John Vig
> > http://www.ieee-uffc.org/fcmain.asp?view=history
> >
> > SPECIAL ISSUE: FIFTY YEARS OF ATOMIC TIME-KEEPING: 1955 TO 2005
> > Metrologia, Volume 42, Number 3, June 2005
> > http://www.iop.org/EJ/news/-topic=945/
> > http://www.iop.org/EJ/toc/0026-1394/42/3
> > includes:
> > - History of early atomic clocks, Norman Ramsey
> > - Essen and the National Physical Laboratory's atomic clock
> > - Atomic time-keeping from 1955 to the present
> > - Fifty years of atomic time-keeping at VNIIFTRI
> > - Fifty years of commercial caesium clocks, Leonard Cutler
> > - and more
> >
> > (some of the above links may require IEEE/UFFC or IOP registration)
> >
> > /tvb
> > http://www.LeapSecond.com
> >
> >
> >
> >
> > _______________________________________________
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> > time-nuts at febo.com
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> >
> >
>
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