{
  "abstract": "Slow positron beams enable diverse applications, from surface-sensitive materials studies to positronium physics, but progress is limited by source intensity and brightness. In linac-based sources, mono-energetic, slow positrons are produced by moderating the broad, divergent distribution of fast positrons produced by high-energy electrons incident on a high-Z target. This process is intrinsically inefficient. Conventional linac-based designs place the moderator close to the target. Tungsten moderators become less efficient when heated by high-power, fast positrons, leading to defect-related losses. Cryogenic moderators, like solid neon, melt when exposed to high-power, fast positrons. Following the method of O'Rourke et al., we use Monte Carlo simulations combined with a diffusion model to investigate how moderator geometry, material, and incident fast positron energy affect slow positron production. We compare single tungsten foil and multi-foil configurations with solid neon moderators in reflection and transmission geometries. We find that for fast positron energies below 300 keV, solid neon offers order-of-magnitude higher efficiency than tungsten due to its larger diffusion length, whereas at MeV-scale energies multi-foil tungsten has higher efficiency due to the maximization of scattering. We also find that including a target proxy in simulation increases low-energy efficiency up to fourfold by allowing a fraction of initially reflected positrons to return to the moderator. We conclude that substantial gains in start-to-end efficiency at linac sources will likely require combining a decelerating cavity with a decoupled cryogenic moderator.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.22036",
  "author_total": 3,
  "authors": [
    {
      "name": "Sophie Crisp"
    },
    {
      "name": "Ryland Goldman"
    },
    {
      "name": "Spencer Gessner"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0gmzbew4rjgzd.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.22036",
  "fulltext_url": null,
  "id": "0gmzbew4rjgzd",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.22036",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.acc-ph"
    ],
    [
      "openalex",
      "2211|Muon and positron interactions and applications"
    ]
  ],
  "openalex": "W7213897855",
  "pdf_url": "https://arxiv.org/pdf/2609.22036",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-18",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0gmzbew4rjgzd.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:03Z",
      "native_id": "2609.22036",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.22036"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.acc-ph",
      "subfield": "applied-instrumentation"
    }
  ],
  "title": "Moderator Modeling for High Intensity Slow Positron Sources",
  "title_text": "Moderator Modeling for High Intensity Slow Positron Sources",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:03Z",
  "url": "https://research.draconitic.com/paper/0gmzbew4rjgzd",
  "venue": "arXiv",
  "versions": []
}