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Observation of Vertical Betatron Sideband due to Electron Clouds in the KEKB LER

J. W. Flanagan·K. Ohmi·H. Fukuma·S. Hiramatsu·M. Tobiyama·E. Perevedentsev
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Abstract

The effects of electron clouds on positively-charged beams have been an active area of research in recent years at particle accelerators around the world. Transverse beam-size blow-up due to electron clouds has been observed in some machines, and is considered to be a major limiting factor in the development of higher-current, higher-luminosity electron-positron colliders. The leading proposed mechanism for beam blow-up is the excitation of a fast head-tail instability due to short-range wakes within the electron cloud. We present here observations of betatron oscillation sidebands in bunch-by-bunch spectra that may provide direct evidence of such head-tail motion in a positron beam.

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J. W. Flanagan, K. Ohmi, H. Fukuma, S. Hiramatsu, M. Tobiyama, E. Perevedentsev. 2005-01-19. Observation of Vertical Betatron Sideband due to Electron Clouds in the KEKB LER. https://doi.org/10.1103/physrevlett.94.054801

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