{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"da5625e1e6164cc1ad9934f48143a993c11889c665ab7f966c3a792dee1ba494","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"bc0a690fc541ab6a2f414a4c2d9bc303c1ad83cd70bb70d447683bae307d4477","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"hep.neutrino-fog.atmospheric-flux","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"For heavy dark matter, the main neutrino background comes from cosmic rays hitting the atmosphere and producing low-energy neutrinos, whose number is poorly measured. Better knowledge of this flux decides how deep heavy dark matter searches can go.","posed_since":"","precise":"The CEvNS background for WIMP masses above about $100\\,\\mathrm{GeV}$ comes from atmospheric neutrinos with $E_\\nu$ below about $100\\,\\mathrm{MeV}$, where the flux has never been measured directly and model uncertainties are of order 20 percent. The quantity is this flux, with its site and solar-cycle dependence, to about 10 percent precision. An answer is a measurement or a validated calculation of the sub-$100\\,\\mathrm{MeV}$ atmospheric $\\nu_e$ and $\\nu_\\mu$ fluxes at underground laboratory sites.","problem_ref":null,"references":"","settled_by":"A measurement of low-energy atmospheric neutrinos in a large detector (e.g., JUNO, Super-Kamiokande with gadolinium, DUNE) or by the first atmospheric CEvNS detection in a dark matter detector.","status_note":"Fan, Liu and Zhou (Chin. Phys. C 49, 103001, 2025) estimated the atmospheric flux at CJPL to be about 30 percent lower than at LNGS, so the fog boundary for heavy WIMPs is site dependent.","title":"How well is the sub-100 MeV atmospheric neutrino flux known?","topic_ref":"8aa34dbf8fe622dfe44455a4a52ccd521c5275a918d302f3967b566a3c2ae8e9"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"f91e3b9a1a36c591a827259faf3eb3291e96015fa88a76864999a8123df29780","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"6e2545d3a2b8c886c5189d72ad9f5775c31734e5b16f84212d08b5b25c4c48cd","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"U2pxA_zpSNSC8OUuagTeaIcyHFd_S2eP1VuKJuNFykE9rWdnD8jZjmAyvO-U5eN4zL58sZlvLKRGNdAkTs2sDg"},"schema":"pubphys.envelope/1"},"record_hash":"f91e3b9a1a36c591a827259faf3eb3291e96015fa88a76864999a8123df29780","leaf_index":1567}