{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"5d02c86178487860d8b7e9f9c28bc215bf393a6295764ea58942198513ca4160","created":"2026-10-03T07:18:06Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"38fd03e995635605f1f94b12dbddeda0c7f5273dafdf8dec57c1a2c9f9ee0f0c","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"med.ion-therapy.fragmentation","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Heavy ions break up when they hit nuclei in tissue, creating lighter fragments that deposit dose past the tumour. The break-up probabilities are not measured well enough.","posed_since":"1990","precise":"Measure and model partial charge-changing and isotopic production cross sections for projectiles of Z from 2 to 10 at 100 to 450 MeV per nucleon on hydrogen, carbon, nitrogen, oxygen and calcium targets, to about 5 percent, including fragment angular and energy distributions. An answer is a cross-section set that lets Monte Carlo transport reproduce measured depth-dose tails to within 1 percent of peak dose.","problem_ref":null,"references":"","settled_by":"Thin-target fragmentation experiments covering the therapeutic energy range, benchmarked against measured depth-dose and lateral profiles.","status_note":"Dedicated campaigns since about 2020 have filled gaps, yet model spread in the fragment tail remained several percent in 2025.","title":"Nuclear fragmentation cross sections for therapy beams","topic_ref":"783c95cea555c72f61498fd08fa3ced7be4a4b07d67abcd2e5bc27204e6bdab5"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"1d9f1a7d04e8d40576a1c08cdd320586aaabed5e4deba39842816b7e10f08eac","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"cb9cc5d48ab82810c2bbdeb00a687ad0029c11fd512733622d2fd81f44d90292","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"UisYuDNRcScrKwYKeZ0ldEvVhrCYvgHmD-o5vrAJYB2K-cMI-cM0uODQj-gWjI2SvVsN_EqOr5_BhHFtArdNBg"},"schema":"pubphys.envelope/1"},"record_hash":"1d9f1a7d04e8d40576a1c08cdd320586aaabed5e4deba39842816b7e10f08eac","leaf_index":1689}