arXiv subjects
Publications and source records attributed to H. Fukuma.
Electron cloud observations at B factories, i.e. KEKB and PEP-II, are reviewed. Predictions of electron cloud effects at Super B factories, i.e. SuperB and Super KEKB, are also reviewed.
Crab cavities have been installed in the KEKB B--Factory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the prediction of simulation.
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.
KEKB is a high luminosity e+e- collider for studying B mesons and has achieved the design luminosity of 1034cm-2s-1 in 2003. In order to get higher luminosity, we tested negative momentum compaction optics in the summer of 2003. We measured the bunch length using three methods at 0.7mA to 1.17mA bunch current and confirmed the length was shortened with the negative momentum compaction optics.