{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"069cb66e04d7b65f1d3fba7b49035c1d96392e782c29bd8618464e6baefc8eb7","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","b9ac9f44652a99795b9547ff2d404bfa7120d276ceb5cc641d745b4bcd729558"],"salt":"b2a8e146123c2589d786cc87546a5753e86561a6046492b07ec0831ef5b2247b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"med.pet.prompt-photons","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"b9ac9f44652a99795b9547ff2d404bfa7120d276ceb5cc641d745b4bcd729558","relation":"special_case"}],"plain":"A crystal that converts a gamma ray into light emits most of it too slowly for very precise timing. Finding or engineering a fast first burst of light is the main limit.","posed_since":"2015","precise":"Identify and engineer prompt emission mechanisms with sub-100 ps rise and a useful photon yield at 511 keV: Cherenkov emission in high-refractive-index media, cross-luminescence in barium fluoride, quantum-confined emission in nanocrystals and metamaterial scintillators, and hot intraband luminescence. Required figures of merit: prompt photons per MeV, emission rise time, self-absorption and extraction efficiency. An answer names a material and reports these quantities.","problem_ref":null,"references":"","settled_by":"Measurement of prompt photon yield and rise time in a candidate material, with the resulting coincidence time resolution in a detector of clinical stopping power.","status_note":"","title":"Fast light emission channels in scintillators","topic_ref":"82c46a639f6fd1f2c6c4e5f93efaf610a76f3cc0784379dd43df49391264c57d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"e2a2ca5064ccee90c441ee497aa8bc5c2b7b9b84c22a921f4dffab66d84b1119","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"9d99cf57e48674699593d77475a3c2a512af7ee2f4eb1fa7391631d87f52052d","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"LGetcSA_wkGXnq88BebQsGnolom0bH-DgA1KOM4qFW8LSp6tBBIqTXQHhDTuAD9HYBgibtDcGc-Lf0eunrvjDA"},"schema":"pubphys.envelope/1"},"record_hash":"e2a2ca5064ccee90c441ee497aa8bc5c2b7b9b84c22a921f4dffab66d84b1119","leaf_index":1717}