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<div class="moz-cite-prefix">On 8/28/2024 12:51 PM, Volker Burkert
via Clas12_rgh wrote:<br>
</div>
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<p class="MsoNormal">Eugene,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I thought we have given up on using the
Hall C magnet. </p>
</div>
</blockquote>
<p>Hi Volker,</p>
<p>I don't think we made a decision yet. What we decided is to
resubmit the proposal to next PAC. I understood we have to
converge by the end of the year with the configuration. Unless we
will have a clear path for central detection we plan to go with
the Hall-C magnet.</p>
<p>Since most of the expenses (beam line + target) are the same we
can have a proposal with Hall-C magnet, which will make possible
first running with transverse target, and later on submit upgrade
proposal (basically just the new magnet+recoil) for additional
time. Given the low luminosity running with transverse target we
will certainly benefit from additional running with the new
magnet.</p>
<p>Best,</p>
<p>Harut<br>
</p>
<blockquote type="cite"
cite="mid:BLAPR09MB6708C76C9F81B6057F2DB714C6952@BLAPR09MB6708.namprd09.prod.outlook.com">
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<p class="MsoNormal"><o:p>
</o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am not saying we should run the program
at 2.5 T. That was just an example that I know from the past.
We don’t want to give up the high polarization at 5Tesla for
the core RGH program. But at the 2-gamma program that Axel
mentioned one has higher rates and maybe the lower
polarization is tolerable. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We should design the magnet for 5T. But if
things go approximately linear, I would think the target would
also work at 11x4/5 and at 11x3/5 GeV. Chris will know if he
can get microwave generators at the corresponding lower
frequencies. So, to get to the lower energies we could then
just lower all magnetic fields of the chicane and of the
target magnet simultaneously and no mechanical changes might
be needed.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Volker<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div id="mail-editor-reference-message-container">
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<div
style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span
style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Eugene
Pasyuk <a class="moz-txt-link-rfc2396E" href="mailto:pasyuk@jlab.org"><pasyuk@jlab.org></a><br>
<b>Date: </b>Wednesday, August 28, 2024 at 12:37 PM<br>
<b>To: </b>Volker Burkert <a class="moz-txt-link-rfc2396E" href="mailto:burkert@jlab.org"><burkert@jlab.org></a>,
Axel Schmidt <a class="moz-txt-link-rfc2396E" href="mailto:schmidta@jlab.org"><schmidta@jlab.org></a><br>
<b>Cc: </b>Eugene Pasyuk via Clas12_rgh
<a class="moz-txt-link-rfc2396E" href="mailto:clas12_rgh@jlab.org"><clas12_rgh@jlab.org></a><br>
<b>Subject: </b>Re: [Clas12_rgh] beam energy<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Aptos",sans-serif;color:black">Volker,<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Aptos",sans-serif;color:black">If we go
2.5 T, the Hall C magnet or its clone would need some
modifications. To get the required field homogeneity
at 5 T, it is shimmed with an iron cylinder. It needs
to be modified to go to a different field, hopefully
just a shim.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Aptos",sans-serif;color:black">But if we
want to run at 2.5 T, we may just design a new magnet.
The forces on the coils will be smaller, and the coil
supports could be lighter. We may get larger
acceptance. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
</div>
<div id="Signature">
<p><span style="color:black">-Eugene</span><o:p></o:p></p>
<p><span style="color:black"> </span><o:p></o:p></p>
<p> <o:p></o:p></p>
</div>
<div class="MsoNormal" style="text-align:center"
align="center">
<hr width="98%" size="2" align="center">
</div>
<div id="divRplyFwdMsg">
<p class="MsoNormal"><b><span style="color:black">From:</span></b><span
style="color:black"> Volker Burkert
<a class="moz-txt-link-rfc2396E" href="mailto:burkert@jlab.org"><burkert@jlab.org></a><br>
<b>Sent:</b> Wednesday, August 28, 2024 12:15<br>
<b>To:</b> Axel Schmidt <a class="moz-txt-link-rfc2396E" href="mailto:schmidta@jlab.org"><schmidta@jlab.org></a>;
Eugene Pasyuk <a class="moz-txt-link-rfc2396E" href="mailto:pasyuk@jlab.org"><pasyuk@jlab.org></a><br>
<b>Cc:</b> Eugene Pasyuk via Clas12_rgh
<a class="moz-txt-link-rfc2396E" href="mailto:clas12_rgh@jlab.org"><clas12_rgh@jlab.org></a><br>
<b>Subject:</b> Re: [Clas12_rgh] beam energy</span> <o:p></o:p></p>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="xmsonormal"><span style="font-size:11.0pt">Hi
Axel,</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt">For
such a large range in energy it might be better to
also lower the polarizing target magnetic field with
the chicane magnets and use different microwave
frequencies. The prize to pay is lower polarization.
In the past people have used 2.5 Tesla mag. field
with still decent polarizations (50-60% for
protons??) . But Chris may want to comment on this
option.
</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt">Volker</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<div id="x_mail-editor-reference-message-container">
<div>
<div
style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="xmsonormal" style="margin-bottom:12.0pt"><b><span
style="font-size:12.0pt;color:black">From:
</span></b><span
style="font-size:12.0pt;color:black">Clas12_rgh
<a class="moz-txt-link-rfc2396E" href="mailto:clas12_rgh-bounces@jlab.org"><clas12_rgh-bounces@jlab.org></a> on behalf
of Axel Schmidt via Clas12_rgh
<a class="moz-txt-link-rfc2396E" href="mailto:clas12_rgh@jlab.org"><clas12_rgh@jlab.org></a><br>
<b>Date: </b>Wednesday, August 28, 2024 at
11:52 AM<br>
<b>To: </b>Eugene Pasyuk
<a class="moz-txt-link-rfc2396E" href="mailto:pasyuk@jlab.org"><pasyuk@jlab.org></a><br>
<b>Cc: </b>Eugene Pasyuk via Clas12_rgh
<a class="moz-txt-link-rfc2396E" href="mailto:clas12_rgh@jlab.org"><clas12_rgh@jlab.org></a><br>
<b>Subject: </b>Re: [Clas12_rgh] beam energy</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">Dear Eugene,</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">Thank you for raising
this issue.</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">Acknowledging that
the approved experiments are all designed for
5th pass beam (and that obviously takes
priority), I would be very curious to know how
much additional cost and effort would be
needed to accommodate 4th pass, or even 3rd
pass beam energies. Lower energies would
probably be a lot better for measuring
two-photon exchange, the physics August and I
are investigating. </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">I realize that this
would require a MUCH larger chicane bend.
Would this increase the size/cost/complexity
by a large factor? At what point does it
become completely infeasible?</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">We are still in the
early stages for exploring this. We'll do
simulations and report to the group. But this
seemed like a good moment to register this
point. </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">Thanks,</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">Axel</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">On Aug 28, 2024, at
11:03, Eugene Pasyuk via Clas12_rgh
<a class="moz-txt-link-rfc2396E" href="mailto:clas12_rgh@jlab.org"><clas12_rgh@jlab.org></a> wrote:</span><o:p></o:p></p>
</div>
<div>
<div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
<div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt;font-family:"Aptos",sans-serif">Hello
RGH enthusiasts,</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt;font-family:"Aptos",sans-serif"> </span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt;font-family:"Aptos",sans-serif">While
thinking of the chicane design, it
occurred to me that, so far, in all
our simulations, we have considered
beam energy of 11 GeV. 11 GeV may not
be available. Since the target magnet
field is fixed to be 5 T, we will have
more bending for lower beam energies.
It has two consequences: more
background in the forward detector and
a larger offset of the middle chicane
magnets. The latter means we would
need a wider opening of the chicane
magnets. The maximum opening for the
existing design that produces enough
BdL needs to be checked with the
company. It may require a substantial
redesign of the magnet compared to the
existing version they built for
someone.</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt;font-family:"Aptos",sans-serif">We
should define the minimum acceptable
beam energy for this experiment and
run simulations with this condition.</span><o:p></o:p></p>
</div>
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt;font-family:"Aptos",sans-serif"> </span><o:p></o:p></p>
</div>
<div id="x_Signature">
<div>
<p class="xmsonormal"><span
style="font-size:11.0pt">-Eugene</span><o:p></o:p></p>
</div>
<p> <o:p></o:p></p>
<p><span
style="font-size:9.0pt;font-family:Helvetica"> </span><o:p></o:p></p>
</div>
<p class="xmsonormal"><span
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</blockquote>
</div>
<p class="xmsonormal"><span
style="font-size:11.0pt"> </span><o:p></o:p></p>
</div>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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