{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"ec6a5132f412a646689a0b38393fefb0fac5f382012c7ca2322aa8e0e1f48154","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","dea5b75dcdbb182ed7a0e7fd916ec327dd01d61c06f3a389f15cf952a3454e20"],"salt":"4d3bbc24e1e02582086d5229ea97bd3a66794433db9f8578d4dee78da5262686","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"beams.muon-ionization-cooling.final-emittance","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"Final-cooling stage is the last step of reaching muon collider emittances","parent_revision":"dea5b75dcdbb182ed7a0e7fd916ec327dd01d61c06f3a389f15cf952a3454e20","relation":"special_case"}],"plain":"The last cooling stage must reduce the beam width to about 25 microns while letting it spread lengthwise only within a set limit. No design has yet met both goals together.","posed_since":"","precise":"Muon collider design studies (MAP, the US Muon Accelerator Program, then IMCC, the International Muon Collider Collaboration) set normalized emittance targets of about eps_T ~ 22.5 to 25 micron transverse and eps_L ~ 70 mm (7.5 MeV m) longitudinal at the end of cooling. Determine whether a final-cooling channel using very high field solenoids ($B \\sim 300 \\text{ to } 400\\,\\mathrm{kG}$) or thick wedge absorbers reaches eps_T <= 25 micron with eps_L <= 75 mm and muon transmission above $\\sim 50\\,\\mathrm{percent}$, including decay losses.","problem_ref":null,"references":"","settled_by":"End-to-end tracking of a realistic final-cooling lattice with engineering-feasible magnets meeting the targets, later confirmed by a demonstrator.","status_note":"Thick-wedge final-cooling designs (2024) and a 2026 dispersion-suppressor study for them aim at the 22 micron transverse target; meeting both targets in one realistic lattice is not yet shown.","title":"Can final cooling reach collider transverse emittance with acceptable longitudinal growth","topic_ref":"cf06ea9df973fe3a057c03ab62554e74eaac4ddf41416780bfff92f0d24ef951"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"40b13bb9c15e4dfcbd63e7634aca11bdbf79b5a5557bef5cebecd3ae5ceb7746","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"a12ca2dcddd284a549c67845abf906f4ca2680debf854642ed9ef1998a97d032","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"dOayDaEg-cJfJcOe_LZDWr0NLHUxoEFZ2Oklw67iYtubGHsd0otEhpd97dvZL3i95l6_VmKHdfLE-y9w964EBg"},"schema":"pubphys.envelope/1"},"record_hash":"40b13bb9c15e4dfcbd63e7634aca11bdbf79b5a5557bef5cebecd3ae5ceb7746","leaf_index":675}