title: Observation of vertical betatron sideband due to electron clouds in the KEKB low energy ring.
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 blowup 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 blowup 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.
authors.affiliation: High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan. john.flanagan@kek.jp
authors.forename: J W
authors.initials: JW
authors.lastname: Flanagan
authors.forename: K
authors.initials: K
authors.lastname: Ohmi
authors.forename: H
authors.initials: H
authors.lastname: Fukuma
authors.forename: S
authors.initials: S
authors.lastname: Hiramatsu
authors.forename: M
authors.initials: M
authors.lastname: Tobiyama
authors.forename: E
authors.initials: E
authors.lastname: Perevedentsev