{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"8a0c5c8581f206b2616e53de8d874180dc4bc783acbb33920fc516a95d112d80","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"26894f5fddffb7e59075c048be8f91157096c27b5cf9e34687289cde5239629b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"beams.microbunching-fel.seeded-pedestal","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"Self-seeding is supposed to make X-ray pulses of one clean color, but a broad background of extra colors remains. Its source has not been fully identified.","posed_since":"","precise":"Hard X-ray self-seeded FELs show a broadband pedestal around the seeded line containing a sizable fraction of the energy. Determine the fractions due to residual SASE noise, sideband instability, electron-beam microbunching from the accelerator, and seed-crystal effects, and the minimum achievable pedestal fraction.","problem_ref":null,"references":"","settled_by":"Spectral measurements with controlled microbunching and undulator taper, compared with 3D FEL simulations using measured electron phase space.","status_note":"","title":"Origin of the spectral pedestal in self-seeded hard X-ray FELs","topic_ref":"96829e4a8214c58e8270f023e22cde3715fc0dd6fc4307b667881195ee4a7930"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"c3a0eae0a67fa2aa1389d90aaa1cbf0c954f6036f498d604fee8d7c149e146f1","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"ed7b871703bb0440429f824ab09a8ed7faf20a72a4be20cb352e9f58979a244c","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"Oq-nzahLk1aUis6E7xr9QNF-6pk24txHm7qRFms9nWDMlraG9X02OJ4VklwXkJejB8_dyx80YSUjEvchwMSFAw"},"schema":"pubphys.envelope/1"},"record_hash":"c3a0eae0a67fa2aa1389d90aaa1cbf0c954f6036f498d604fee8d7c149e146f1","leaf_index":671}