[time-nuts] Zeeman effect and tuning cesium clocks

jim_johnson at agilent.com jim_johnson at agilent.com
Tue Jan 25 14:53:31 EST 2005


Hello all,

   I was curious about the flying clock experiments
mentioned below so I went to "the source", who must
remained unnamed, unfortunately (to keep from being
inundated with other requests, etc.).  I refer to him
as "the source" because he actually did the flying
clock experiments in the 70's.  Here's his response
to the reflector postings below:

---------------------------------------------------------------------

Hi Jim,

The transition used for the frequency standard is dependent 
on the magnetic field only to second order.  The magnetometer 
transitions are dependent on field to first order and so, for 
small fields, are much more sensitive to the field.  Also, 
the shielding used is very good and in addition, in the Carrol 
Alley experiment, there was additional shielding around the clocks.  
In the 5071, we servo the magnetic field to be constant and this 
again helps a great deal, but the clocks in the Carrol Alley 
experiment were not 5071s.

In the Carrol Alley experiment, we were looking for the gravitational 
effect and so we flew as high and as slow as possible to maximize 
the effect.  The relativistic effects were about 1E-12 and our 
measurements were good to perhaps 2E-14 so we did about a 2% experiment.

-----------------------------------------------------------------------

Regards,
Jim Johnson
Agilent Laboratories
Palo Alto, CA



>-----Original Message-----
>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>Behalf Of Tom Van Baak
>Sent: Saturday, January 22, 2005 5:03 PM
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] Zeeman effect and tuning cesium clocks
>
>
>
>> Now I'm wondering how they ever got two portable cesium beam
>> clocks of the seventies to show relativistic affects when their
>> accuracy depends on external magnetic fields.
>
>The magnetic effect is not a big issue. It's all part of
>the design and the tubes shielded just enough to meet
>the accuracy spec of the instrument. On the other
>hand I've heard that unshielded atomic clocks are
>specifically used to measure magnetic fields!
>
>Inthe 70's they flew fast and high enough and so the
>relativistic effects were in the tens of microseconds.
>
>
>/tvb
>

--------------------------------------------------------------

Now I'm wondering how they ever got two portable cesium beam
clocks of the seventies to show relativistic affects when their
accuracy depends on external magnetic fields.


Regards,
Bill Hawkins




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