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@inproceedings{nakayama:ipac2021-wexa07,
author = {H.N. Nakayama and T. Koga and K. Kojima and A. Natochii and S. Vahsen},
title = {{Beam Background Measurements at SuperKEKB/Belle-II in 2020}},
booktitle = {Proc. IPAC'21},
pages = {2532--2535},
eid = {WEXA07},
language = {english},
keywords = {background, luminosity, injection, detector, scattering},
venue = {Campinas, SP, Brazil},
series = {International Particle Accelerator Conference},
number = {12},
publisher = {JACoW Publishing, Geneva, Switzerland},
month = {08},
year = {2021},
issn = {2673-5490},
isbn = {978-3-95450-214-1},
doi = {10.18429/JACoW-IPAC2021-WEXA07},
url = {https://jacow.org/ipac2021/papers/wexa07.pdf},
note = {https://doi.org/10.18429/JACoW-IPAC2021-WEXA07},
abstract = {{The SuperKEKB electron-positron collider began collision operation in 2018 and achieved the world-record luminosity of 2.4x10³⁴~cm⁻²s⁻¹ in June 2020. We pursue higher luminosity by squeezing beam sizes and increasing beam currents. Beam backgrounds induced by stray particles will also increase and might cause severe radiation damage to Belle II detector components and worsen the quality of collected physics data. To mitigate these backgrounds, we have carefully designed our interaction region and installed movable collimators in the machine. We present recent measurements of beam background at SuperKEKB. We have performed dedicated machine studies to measure each background component separately and found that beam-gas scattering and Touschek scattering in the positron ring are the dominant sources of background rates in Belle II. We also present the latest observations of injection background, which determines the timing of a required Belle II data acquisition trigger veto and therefore affects the integrated luminosity. We show the beam background extrapolation toward the expected higher-luminosity operation and our plans for further background mitigation.}},
}