[PEPPo] An idea for the positron converter location

[Andrei Seryi]

Colleagues,
Here is a paper about compact damping ring for 335MeV positrons for FACET-II project.
The ring is so compact, it can fit to existing SLAC tunnel without any construction.
I am not suggesting to add damping ring to CEBAF! 😊
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.
https://accelconf.web.cern.ch/ipac2017/papers/thoba3.pdf
https://accelconf.web.cern.ch/ipac2017/talks/thoba3_talk.pdf
Hope it helps as an inspiration.

Thanks
  Andrei



From: PEPPo <peppo-bounces at jlab.org> on behalf of Dennis Turner via PEPPo <peppo at jlab.org>
Reply-To: Dennis Turner <dturner at jlab.org>
Date: Wednesday, November 15, 2023 at 11:02
To: "peppo at jlab.org" <peppo at jlab.org>, Reza Kazimi <kazimi at jlab.org>, Max Bruker <bruker at jlab.org>, Yves Roblin <roblin at jlab.org>
Subject: Re: [PEPPo] An idea for the positron converter location

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.

Dennis

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From: PEPPo <peppo-bounces at jlab.org> on behalf of Yves Roblin via PEPPo <peppo at jlab.org>
Sent: Wednesday, November 15, 2023 10:51
To: peppo at jlab.org <peppo at jlab.org>; Reza Kazimi <kazimi at jlab.org>; Max Bruker <bruker at jlab.org>
Subject: Re: [PEPPo] An idea for the positron converter location

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.
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From: PEPPo <peppo-bounces at jlab.org> on behalf of Max Bruker via PEPPo <peppo at jlab.org>
Sent: Wednesday, November 15, 2023 10:17 AM
To: peppo at jlab.org <peppo at jlab.org>; Reza Kazimi <kazimi at jlab.org>
Subject: Re: [PEPPo] An idea for the positron converter location

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?

Max
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From: PEPPo <peppo-bounces at jlab.org> on behalf of Reza Kazimi via PEPPo <peppo at jlab.org>
Sent: Wednesday, November 15, 2023 9:45 AM
To: peppo at jlab.org <peppo at jlab.org>
Subject: Re: [PEPPo] An idea for the positron converter location

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.

See you in the meeting.

Thanks
Reza,

Reza Kazimi
Jefferson Lab
kazimi at jlab.org
________________________________
From: Reza Kazimi <kazimi at jlab.org>
Sent: Wednesday, November 15, 2023 12:10:44 AM
To: peppo at jlab.org <peppo at jlab.org>
Subject: An idea for the positron converter location

Hi everyone,

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.

Reza,


Reza Kazimi
Jefferson Lab
kazimi at jlab.org
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