{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"a946432136e5825733279b3808bc5889fb926f01e2c6eef767a911b1b4bc38d1","created":"2026-10-03T07:18:06Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1abf2f70c76d7498672e6b42237fa644d250ab0f4c3cbf2fbac653022f851e85","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"med.bnct.accelerator-source","kind":"well-posed","literature_status":"partially-resolved","n":"1","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 x 10^-11 rad 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":null,"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":"0c8039c980b31f825989ca36e1cd7529f5aab83d616e66638b0e9746fc03ac15"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"ac2fbbf8a9ddeec402c9c5aad060fa656f51d59c4d76411f312454c244cc8352","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"9977ce7e8e53819b8948c8c1cedc4e3d2756d97f71ca48a0a88f0ad30d290104","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"mVPiZ9QfXJUEPDT4pL85Zi7AX16Pviys2oinL75cH0xwYu89afwOMe8UJewh1FoRz4pzffHgJUHXgf7l5MhbCw"},"schema":"pubphys.envelope/1"},"record_hash":"ac2fbbf8a9ddeec402c9c5aad060fa656f51d59c4d76411f312454c244cc8352","leaf_index":1665}