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Response from Dan Sober,<br>
<blockquote type="cite"> Richard,<br>
Hall B lived without a field probe for a long time, just trusting the
current setting procedure and monitoring the current -- seemed to be
consistent to much better than 10^-3. Eventually (in 2004) a Hall probe
was installed, but I think it is just read out into the data base, not
used for feedback. If the current regulation is good, then I don't
think field feedback is necessary, unless new operating experience
tells us otherwise.<br>
Dan<br>
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Alexander Somov wrote:
<blockquote type="cite" cite="mid:Pine.LNX.4.64.0910080847020.394@jlabl1.jlab.org">
<pre wrap="">Hi,
Do you know whether the Hall-B used a feedback in their magnet ?
Is it a temperature variation in the magnet that leads to the
field variation for the constant current/voltage (I would talk to the
magnet experts and try to find out the magnitude of the field
instability) ? ( would Paul Brindza be the right person to discuss ? )
Cheers,
Alex
P.S. On the other hand $20k is not an extreme amount.
Perhaps it's better to have the feedback system...
On Wed, 7 Oct 2009, Tim Whitlatch wrote:
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<pre wrap="">Hi Gents,
Have we decided whether or not we can live without an NMR controller on the
tagger magnet power supply? I know we want to know the field with the probes
but do we need to have the feedback to automatically adjust? This may
determine whether or not we can get a rebuilt controller from JLAB for about
$20K.
Tim
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