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TY - CONF AU - Terui, S. AU - Funakoshi, Y. AU - Hisamatsu, H. AU - Ishibashi, T. AU - Kanazawa, K. AU - Ohnishi, Y. AU - Shibata, K. AU - Shirai, M. AU - Suetsugu, Y. AU - Tobiyama, M. ED - Liu, Lin ED - Byrd, John M. ED - Neuenschwander, Regis T. ED - Picoreti, Renan ED - Schaa, Volker R. W. TI - Report on Collimator Damaged Event in SuperKEKB J2 - Proc. of IPAC2021, Campinas, SP, Brazil, 24-28 May 2021 CY - Campinas, SP, Brazil T2 - International Particle Accelerator Conference T3 - 12 LA - english AB - Collimator jaws for SuperKEKB main ring, which is an electron-positron collider, installed to suppress background noise in a particle detector complex named Belle II. In high current operations with 500 mA or more, jaws were occasionally damaged by hitting abnormal beams. This trouble is a low-frequency, which is once-a-commissioning period currently, but high-consequence one because we are not able to apply high voltage on detectors in Belle II by high backgrounds. At this moment this jaw damage event occurs, we observed pressure burst near the collimator with the beam abort, there was no sign of beam oscillation indicating instability, and the beam intensity suddenly decreased a few turns before the abort. I predict that the cause of this jaw damage was that a sudden change of the beam energy by the collision with dust. In this paper, the explanation of the observation result of this events and tracking simulation of beam colliding with dust are reported. PB - JACoW Publishing CP - Geneva, Switzerland SP - 3541 EP - 3544 KW - electron KW - detector KW - positron KW - MMI KW - operation DA - 2021/08 PY - 2021 SN - 2673-5490 SN - 978-3-95450-214-1 DO - doi:10.18429/JACoW-IPAC2021-WEPAB359 UR - https://jacow.org/ipac2021/papers/wepab359.pdf ER -