{"schema":"pubphys.bundle/1","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 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