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<p class="MsoNormal">Colleagues, <o:p></o:p></p>
<p class="MsoNormal">Here is a paper about compact damping ring for 335MeV positrons for FACET-II project.
<o:p></o:p></p>
<p class="MsoNormal">The ring is so compact, it can fit to existing SLAC tunnel without any construction.
<o:p></o:p></p>
<p class="MsoNormal">I am not suggesting to add damping ring to CEBAF! <span style="font-family:"Apple Color Emoji"">
😊</span> <o:p></o:p></p>
<p class="MsoNormal">But it demonstrates that for twice higher energy beam one can have 180 degree bends with all needed control of optics, which is perhaps more difficult for a ring than for a return line. <o:p></o:p></p>
<p class="MsoNormal"><a href="https://accelconf.web.cern.ch/ipac2017/papers/thoba3.pdf">https://accelconf.web.cern.ch/ipac2017/papers/thoba3.pdf</a><o:p></o:p></p>
<p class="MsoNormal"><a href="https://accelconf.web.cern.ch/ipac2017/talks/thoba3_talk.pdf">https://accelconf.web.cern.ch/ipac2017/talks/thoba3_talk.pdf</a><o:p></o:p></p>
<p class="MsoNormal">Hope it helps as an inspiration. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal"> Andrei<o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">PEPPo <peppo-bounces@jlab.org> on behalf of Dennis Turner via PEPPo <peppo@jlab.org><br>
<b>Reply-To: </b>Dennis Turner <dturner@jlab.org><br>
<b>Date: </b>Wednesday, November 15, 2023 at 11:02<br>
<b>To: </b>"peppo@jlab.org" <peppo@jlab.org>, Reza Kazimi <kazimi@jlab.org>, Max Bruker <bruker@jlab.org>, Yves Roblin <roblin@jlab.org><br>
<b>Subject: </b>Re: [PEPPo] An idea for the positron converter location<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">The first thing that pops into my mind is the radiological aspect. The labyrinth itself is an engineered control. Perhaps the additional shield walls be enough, but I don't know.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Dennis<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> PEPPo <peppo-bounces@jlab.org> on behalf of Yves Roblin via PEPPo <peppo@jlab.org><br>
<b>Sent:</b> Wednesday, November 15, 2023 10:51<br>
<b>To:</b> peppo@jlab.org <peppo@jlab.org>; Reza Kazimi <kazimi@jlab.org>; Max Bruker <bruker@jlab.org><br>
<b>Subject:</b> Re: [PEPPo] An idea for the positron converter location</span> <o:p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">yes I had the same concerns. Bending 180 after the target would be very difficult with the large phase space and energy spread. Doing it before is of course possible, its just a 123 MeV e- beam,
abeilt with large space charge. I guess, we won't know until we attempt to do a mock optics design.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> PEPPo <peppo-bounces@jlab.org> on behalf of Max Bruker via PEPPo <peppo@jlab.org><br>
<b>Sent:</b> Wednesday, November 15, 2023 10:17 AM<br>
<b>To:</b> peppo@jlab.org <peppo@jlab.org>; Reza Kazimi <kazimi@jlab.org><br>
<b>Subject:</b> Re: [PEPPo] An idea for the positron converter location</span> <o:p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">What worries me about this idea, apart from transporting 2 pC through the CEBAF injector (need diagnostics, the booster FPCs may limit the current, etc.), is the question of how to manage the dispersion
of all those positron bends; capturing and accelerating the positrons is already difficult in a straight line. I don't have a good sense of what it would take to make that work because the optics may take up a lot of space and it's not clear to me what we
are working with. What is your logic for wanting to place the 180° bend after the production target as opposed to before?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Max<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> PEPPo <peppo-bounces@jlab.org> on behalf of Reza Kazimi via PEPPo <peppo@jlab.org><br>
<b>Sent:</b> Wednesday, November 15, 2023 9:45 AM<br>
<b>To:</b> peppo@jlab.org <peppo@jlab.org><br>
<b>Subject:</b> Re: [PEPPo] An idea for the positron converter location</span> <o:p>
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<p class="MsoNormal">What I left out is that I already had a discussion with Jay Benesch on Friday and he pulled out the drawings of the tunnel to make sure things can fit. He even suggested we may be able to cut through some of the walls to make the bends
less sharp. Then Jay mentioned it to Andrei Seryi and the two questions I have at the end are actually from Andrei.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">See you in the meeting.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Reza,</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Reza Kazimi<o:p></o:p></p>
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<p class="MsoNormal">Jefferson Lab<o:p></o:p></p>
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<p class="MsoNormal">kazimi@jlab.org<o:p></o:p></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> Reza Kazimi <kazimi@jlab.org><br>
<b>Sent:</b> Wednesday, November 15, 2023 12:10:44 AM<br>
<b>To:</b> peppo@jlab.org <peppo@jlab.org><br>
<b>Subject:</b> An idea for the positron converter location </span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">Hi everyone,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">In line with Andrei's new proposal, if we start from present injector, there may be a way to add a positron converter without a new tunnel construction or significant disruption to the existing configuration. I am sending a few slides for
your consideration. Please see the attached ppt. I have a few questions at end that needs to be answered. Please excuse my excellent artwork. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Reza,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Reza Kazimi<o:p></o:p></p>
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<p class="MsoNormal">Jefferson Lab<o:p></o:p></p>
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<p class="MsoNormal">kazimi@jlab.org<o:p></o:p></p>
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