{
  "abstract": "Direct dark matter detection with NaI(Tl) scintillators requires ultra-low-background materials. Silicone optical pads can couple NaI(Tl) crystals to photomultiplier tubes (PMTs) if they provide adequate optical transmission and radiopurity. We characterize four candidate materials for the SABRE-North experiment: commercial EJ-560, used as a reference, and three materials produced at the University of Salento (SYLGARD 184, EGel 3002 A/B, and a hybrid formulation) using different catalyst ratios and curing conditions, yielding ten samples in total. Optical transmittance was measured from 310 to 850 nm by UV/Vis/NIR spectrophotometry. Radiopurity was assessed at the STELLA facility at LNGS using high-purity germanium (HPGe) $γ$-ray spectrometry and, for EJ-560, high-resolution ICP-MS. At the 410 nm NaI(Tl) emission peak, EJ-560 shows an absorbance coefficient of $0.064\\pm0.017$ mm$^{-1}$. The best locally produced samples reach $0.097\\pm0.015$ and $0.093\\pm0.014$ mm$^{-1}$ for SYLGARD 184 with a 10:2 base-to-catalyst ratio cured at room temperature and at $40^\\circ$C, respectively, $0.125\\pm0.015$ mm$^{-1}$ for EGel 3002 with a 2B:A ratio cured at $40^\\circ$C, and $0.106\\pm0.014$ mm$^{-1}$ for the hybrid 10:1 EGel A:CataSYL formulation cured at room temperature. EJ-560 exhibits detectable $^{232}$Th-chain activity at about 1.8 mBq/kg and the highest $^{40}$K activity, $(120\\pm20)$ mBq/kg. The locally produced materials show no detectable Th-chain contamination but exhibit $^{226}$Ra activities of about 2.3 mBq/kg and lower $^{40}$K levels. No single material is optimal across all criteria. Additional ICP-MS screening, HPGe measurements of cured pads, and direct NaI(Tl)-PMT light-yield tests are required for a conclusive SABRE-North material selection.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.06029",
  "author_total": 24,
  "authors": [
    {
      "name": "Chemseddine Ananna"
    },
    {
      "name": "Gabriella Cataldi"
    },
    {
      "name": "Davide D'Angelo"
    },
    {
      "name": "Giulia D'Imperio"
    },
    {
      "name": "Maria Luisa De Giorgi"
    },
    {
      "name": "Giuseppe Di Carlo"
    },
    {
      "name": "Attilio Di Giacinto"
    },
    {
      "name": "Marcella Diemoz"
    },
    {
      "name": "Aldo Ianni"
    },
    {
      "name": "Sana Gul Khattak"
    },
    {
      "name": "Edoardo Martinenghi"
    },
    {
      "name": "Alessandro Miccoli"
    },
    {
      "name": "Marcin Misiaszek"
    },
    {
      "name": "Daniele Montanino"
    },
    {
      "name": "Valerio Pettinacci"
    },
    {
      "name": "Lidio Pietrofaccia"
    },
    {
      "name": "Shahram Rahatlou"
    },
    {
      "name": "Krzysztof Szczepaniec"
    },
    {
      "name": "Claudia Tomei"
    },
    {
      "name": "Valerio Toso"
    },
    {
      "name": "Chiara Vignoli"
    },
    {
      "name": "Samina Zuhra"
    },
    {
      "name": "Francesco Ferella"
    },
    {
      "name": "Stefano Nisi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/14s5669kfnzy9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.06029",
  "fulltext_url": null,
  "id": "14s5669kfnzy9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.06029",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.IM"
    ],
    [
      "arxiv",
      "physics.ins-det"
    ],
    [
      "openalex",
      "3108|Radiation Detection and Scintillator Technologies"
    ]
  ],
  "openalex": "W7220711193",
  "pdf_url": "https://arxiv.org/pdf/2610.06029",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-05",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/14s5669kfnzy9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:01Z",
      "native_id": "2610.06029",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.06029"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.IM",
      "subfield": "instrumentation-methods"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.ins-det",
      "subfield": "applied-instrumentation"
    }
  ],
  "title": "Investigating Optical Coupling Material Candidates in NaI(Tl) Detectors for the SABRE-North Dark Matter Experiment",
  "title_text": "Investigating Optical Coupling Material Candidates in NaI(Tl) Detectors for the SABRE-North Dark Matter Experiment",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:01Z",
  "url": "https://research.draconitic.com/paper/14s5669kfnzy9",
  "venue": "arXiv",
  "versions": []
}