Moderator Simulation for the Compact Positron Source at NLCTA

Fuente: arXiv
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Main Authors: Goldman, Ryland, Crisp, Sophie, Gessner, Spencer
Format: Preprint
Published: 2025
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author Goldman, Ryland
Crisp, Sophie
Gessner, Spencer
author_facet Goldman, Ryland
Crisp, Sophie
Gessner, Spencer
contents Positron moderation is a key part of the production of slow positrons. This paper examines G4beamline simulations of various moderator designs and the addition of a radiofrequency cavity to increase the efficiency of the moderator. A setup consisting of a 100 MeV electron beam incident on a 7 mm tungsten target, a 5 T adiabatic matching device, a 5-cell L-band RF cavity, and a single-crystal tungsten moderator leads to a 39.3x improvement in the number of positrons moderated over a common thin-foil polycrystalline moderator without the AMD and cavity. We also present a novel calculation method for determining the stopping distribution of low-energy positrons in a thin foil, modifying the Makhovian distribution with an exponential ramp to account for edge effects.
format Preprint
id arxiv_https___arxiv_org_abs_2508_15975
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Moderator Simulation for the Compact Positron Source at NLCTA
Goldman, Ryland
Crisp, Sophie
Gessner, Spencer
Accelerator Physics
Positron moderation is a key part of the production of slow positrons. This paper examines G4beamline simulations of various moderator designs and the addition of a radiofrequency cavity to increase the efficiency of the moderator. A setup consisting of a 100 MeV electron beam incident on a 7 mm tungsten target, a 5 T adiabatic matching device, a 5-cell L-band RF cavity, and a single-crystal tungsten moderator leads to a 39.3x improvement in the number of positrons moderated over a common thin-foil polycrystalline moderator without the AMD and cavity. We also present a novel calculation method for determining the stopping distribution of low-energy positrons in a thin foil, modifying the Makhovian distribution with an exponential ramp to account for edge effects.
title Moderator Simulation for the Compact Positron Source at NLCTA
topic Accelerator Physics
url https://arxiv.org/abs/2508.15975