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<div class="moz-cite-prefix">Hi Eugene,<br>
<br>
It looks like they already use this method in Hall-A, or at least
have in the past. (<a class="moz-txt-link-freetext" href="https://www.jlab.org/compton/Virtual_manual/index.html">https://www.jlab.org/compton/Virtual_manual/index.html</a>)<br>
In Hall-B they have a Moeller polarimeter, which has a separate
target (magnetized foil + solenoid) and detectors, but could
probably be replicated (in fact Hovanes used to be the expert on
that system).<br>
<br>
Both methods would need additional hardware.<br>
<br>
In Mainz we also measure the electron polarization using Moeller
polarimetry, but it's part of the standard setup. We have the
Moeller foil+solenoid in the goni chamber as an extra target on
the goni translation axis. We also use this as the amorphous
radiator most of the time. If the solenoid is energized we can
make a moeller measurement by looking at coincident pairs of hits
on the tagger focal plane. It might be possible to do something
similar in HallD.<br>
<br>
Regards,<br>
Ken<br>
<br>
<br>
<br>
On 14/10/2020 08:05, Eugene Chudakov wrote:<br>
</div>
<blockquote type="cite" cite="mid:BLAPR09MB66576F27846656257482D27AC7050@BLAPR09MB6657.namprd09.prod.outlook.com">
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);"> I mentioned at the beam
meeting that one can potentially detect/monitore the circular
polarization of a photon beam, but did not remember the details.
Meanwhile, I recalled it - one can use the Compton scattering on
longitudinally polarized electrons (in iron). I attach a few
plots showing the kinematics, the cross section and the
analyzing power. I do not know at this time whether it is
practical or not for the GDH project.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);"> <br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);"> Eugene</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);"> <br>
</div>
<br>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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