[PEPPo] Start-To-End Simulations of a Compact, Linac-Based Positron Source

[Joe Grames]

Sophie and Spencer will be presenting at the November LEEPP workshop here at JLab!
-Joe
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From: PEPPo <peppo-bounces at jlab.org> on behalf of Jay Benesch via PEPPo <peppo at jlab.org>
Sent: Tuesday, August 12, 2025 9:31 AM
To: peppo at jlab.org <peppo at jlab.org>
Subject: [PEPPo] Start-To-End Simulations of a Compact, Linac-Based Positron Source

interesting



https://arxiv.org/abs/2508.07549

Start-To-End Simulations of a Compact, Linac-Based Positron Source

Sophie Crisp, Ryland Goldman, Arif Ismail, Spencer Gessner

Slow positrons are increasingly important to the study of material
surfaces. For these kinds of studies, the positrons must have low
emittance and relatively high brightness. Unfortunately, fast positron
sources like radioactive capsules or linac driven sources have broad
energy and angular spread, which make them difficult to capture and use.
Moderators are materials that produce slow, mono-energetic positrons
from a fast positron beam. Since their efficiencies are typically less
than  slow  per fast , research into how to maximize efficiency
is of great interest. Previous work has shown that using a linac, one
can decelerate the fast positron beam in order to greatly increase
moderation efficiency. We present here start-to-end simulations using
G4beamline to model a 100 MeV electron beam incident upon a Tungsten
target, focused by an adiabatic matching device, and decelerated by a
1.3 GHz, 5-cell pillbox cavity. We show that by decelerating the
positrons after their creation we can increase the number of positrons
under 500 keV by 15 times, translating to a 16.3 times improvement in
moderation efficiency, and therefore leading to a brighter positron source.

Subjects:       Accelerator Physics (physics.acc-ph)
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