{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"055a9d1599e9789737446ddef6c376de769ce37e5de35621b0cdfbbbbe3cbaed","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","e40db54d49b7bbcae272f1539b8bcc9bf6317cdea1fb76b8ba7ab069c56691ac"],"salt":"99abfbb7d4cdd30ded04f38b1833df7c240775dfa638046f7dac2f222aa7e111","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"hep.sterile-neutrino-anomalies.gallium-anomaly","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"e40db54d49b7bbcae272f1539b8bcc9bf6317cdea1fb76b8ba7ab069c56691ac","relation":"special_case"}],"plain":"Experiments placing strong radioactive neutrino sources inside gallium consistently record fewer captures than predicted. The cause, new physics or a wrong cross section, is unknown.","posed_since":"","precise":"The BEST (2022), GALLEX and SAGE source experiments measure $R = \\mathrm{observed}/\\mathrm{predicted} \\sim 0.8$ for Ga-71(nu_e, e-)Ge-71 with Cr-51 and Ar-37 sources, about $4\\sigma$ below 1. Determine whether the deficit comes from the capture cross section (Ge-71 excited-state transitions, half-life), the source activity, or oscillation, in tension with reactor and solar limits.","problem_ref":null,"references":"","settled_by":"An independent source experiment with a different target and an improved measurement of the Ga-71 to Ge-71 matrix elements and Ge-71 half-life.","status_note":"Remeasurements of the Ge-71 half-life (2023 to 2024) did not remove the deficit; sterile oscillation explanations conflict with reactor and solar data.","title":"Why do gallium detectors see about 20 percent fewer neutrino captures?","topic_ref":"7c3a93300e8710b41f3d7fcb0f1c9a791d835219d51f56a2ebbdc44a8de8988d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"c664ceaddb13167825008e46951c95c0bde36e1fcf6357ee27e12bcebab21aa0","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"419715350f2541be45dbb36805ad72acfd0183425d676bbcd34370bdb6ff8be1","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"oNQa1AksahO495nWlO3iNSUrmp5ph-BzRGwOxSwAuZ0EIhtdgwQjpHKEy45-JMJ94yLmpeQ-oON1q1zT_btNAQ"},"schema":"pubphys.envelope/1"},"record_hash":"c664ceaddb13167825008e46951c95c0bde36e1fcf6357ee27e12bcebab21aa0","leaf_index":1578}