{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"d0931eaa89148557ecb3dc3e5f109a3960d9e6e6352bcce98d24aaea6581c3a0","created":"2026-10-03T07:17:56Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"c97da164511a051c1b24038fefa95e09b616d1537cdb7de7f9476f3326a4140d","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"beams.collective-instabilities.superkekb-sudden-loss","kind":"phenomenon","literature_status":"partially-resolved","n":"1","parents":[],"plain":"The SuperKEKB collider in Japan repeatedly loses much of a stored beam within a few turns, together with pressure bursts in the vacuum pipe.","posed_since":"","precise":"SuperKEKB, mainly its low-energy positron ring, shows sudden beam loss events in which bunches begin to oscillate and grow within a few revolutions and hit collimators, correlated with local vacuum pressure bursts recorded by bunch-by-bunch monitors. Determine the physical chain from the source to fast blow-up (dust or debris entering the beam, discharge, ion or electron trapping), with timescale and intensity dependence matching monitor data.","problem_ref":null,"references":"","settled_by":"A model reproducing the measured onset time, bunch pattern and pressure correlation, confirmed by removal of the identified source eliminating the events.","status_note":"Terui et al. (Phys. Rev. Accel. Beams 29, 093501, 2026, https://doi.org/10.1103/pyl3-rfjg) traced the events, more than 200 in 2019-2024 and mainly in the low-energy ring, to stains of degraded vacuum sealant whose removal sharply reduced their frequency; the beam-dynamics chain from contaminant to loss within a few turns is not established.","title":"Mechanism of sudden beam losses at SuperKEKB","topic_ref":"dd60e631adb08b9b18495c7a3ab1cfd2ffd7375b33108ba5cf5ec6cce7af2868"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"d4a7c0d492d42e078f99f50c523b78f7b11aad2a5c9c2261e4c40c580e44f107","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bf1b42f8e8e45bf40db2e78a81ad94a82a451203f262bb265d6ce934891a3b45","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"TjqDQ62qewVHxgNRFWoF2dMVKetsLfIeA-H64S03Q3YqpLPTTbaX06QxLJtYX-quhleu8oz8JnST6Va_4OC1CQ"},"schema":"pubphys.envelope/1"},"record_hash":"d4a7c0d492d42e078f99f50c523b78f7b11aad2a5c9c2261e4c40c580e44f107","leaf_index":659}