{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.topic/1","content_sha256":"2683cbf991085d2c1eb2633423b5dc392ac27f849d78f06a3da7c58a44bd38eb","created":"2026-10-03T07:17:50Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":[],"salt":"4fdcb959cec484cccb7b8945b872c63755956c6bc27281ef4d85d129ed8916b1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"topic"},"content":{"external_id":"beams.photocathode-emittance","field":"beams","n":"1","review_cite":"D. H. Dowell, J. F. Schmerge, Quantum efficiency and thermal emittance of metal photocathodes, Physical Review Special Topics - Accelerators and Beams, 2009","review_link":"https://doi.org/10.1103/PhysRevSTAB.12.074201","review_verified":"true","summary":"Electron beams for X-ray lasers and electron microscopes start when light knocks electrons out of a surface, and the sideways jitter of those electrons sets how sharp the beam can ever be. How small this jitter can be made is unknown.","title":"Minimum intrinsic emittance of photocathodes","topic_ref":null,"why":"Intrinsic emittance sets the brightness of photoinjectors and thus the reach of X-ray FELs and ultrafast electron diffraction."},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"3bfc449fad2e2a963a0690d6313e4ff691a1a4e0f7733f3d2f046a8c26c65ad7","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"0ca2650ac613fad7efe7cc987862d30d1a953c24fa4325f6972a1ce3c963a218","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"3Koln1wa14lGYuki7m1HKRxFnznf9UnbeJLYGo8QjcYfl13afzYnmC3RLgAKYHIYLx2uQOFRnZQfVZLHtPwmAQ"},"schema":"pubphys.envelope/1"},"record_hash":"3bfc449fad2e2a963a0690d6313e4ff691a1a4e0f7733f3d2f046a8c26c65ad7","leaf_index":71}