{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"359e3a574c924462094a6bf9facc6abda85ac5452bff7a0c14aa6e0858352b9c","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["ac2fbbf8a9ddeec402c9c5aad060fa656f51d59c4d76411f312454c244cc8352","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"1d49bb19e13d023f5acc3067ab4c4a41fa30ecb8015ef7caeae37ce9d685b913","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":["ai:gpt-5.5"],"external_id":"med.bnct.accelerator-source","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"Hospitals need compact accelerators that produce intense beams of medium-speed neutrons without too many fast neutrons or gamma rays. The targets that make the neutrons wear out quickly.","posed_since":"","precise":"Design an accelerator-driven source giving epithermal neutron flux above $10^9\\,\\mathrm{per}\\,\\mathrm{cm}^2\\,\\mathrm{per}\\,\\mathrm{s}$ at the beam port with fast-neutron and photon dose per epithermal neutron below the IAEA-recommended limits (of order $2 \\times 10^{-11}$ $\\mathrm{rad}\\ \\mathrm{cm}^{2}$ each), using $\\mathrm{Li}-7(p,n)$, $\\mathrm{Be}-9(p,n)$ or $(d,n)$ reactions, with target lifetime of at least hundreds of treatment hours under proton-induced blistering and heat loads of order $10^{11}\\,\\mathrm{erg}/\\mathrm{s}$. An answer is a source with measured spectrum, flux and target lifetime meeting all criteria.","problem_ref":"ac2fbbf8a9ddeec402c9c5aad060fa656f51d59c4d76411f312454c244cc8352","references":"","settled_by":"Measured beam-port spectra and dose components plus target endurance tests on an operating clinical source.","status_note":"An accelerator-based neutron capture system was approved in Japan in 2020 for head and neck cancer, while target lifetime and beam quality at lithium targets remain under development.","title":"Accelerator neutron sources meeting epithermal beam requirements","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"efa660a8840eb9cf78d90699c1062fe83a6aff54bb5ea6e29a17e39209178916","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"9fc60cf74826cdee4827412bc6447ad602a959635b7c8ac12fde97e149b10235","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"OktsRsgmbGwq2SEtprBUAg207STiPfso6yoBi3b-lTwQynNl2Ke9JJeGDzLXD_lHGedcPuaD7_IW0a6DnnsVDA"},"schema":"pubphys.envelope/1"},"record_hash":"efa660a8840eb9cf78d90699c1062fe83a6aff54bb5ea6e29a17e39209178916","leaf_index":3460}