| Paper |
Title |
Page |
| MOPP059 |
Study for ILC Damping Ring at KEKB
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676 |
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- K. Ohmi, J. W. Flanagan, H. Fukuma, K.-I. Kanazawa, H. Koiso, M. Masuzawa, Y. Ohnishi, K. Oide, Y. Suetsugu, M. Tobiyama
KEK, Ibaraki
- M. T.F. Pivi
SLAC, Menlo Park, California
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ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
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| TUOBG01 |
Observations of Beam-beam Tune Spectrum and Measurement of Coherent Tune Shift at KEKB
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962 |
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- T. Ieiri, Y. Ohnishi, M. Tobiyama, S. Uehara
KEK, Ibaraki
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KEKB is a double-ring electron/positron collider with a horizontal crossing angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. Under the new crabbing collision as well as the horizontal crossing collision, tune spectra of a colliding bunch were observed on a spectrum analyzer to study beam-beam effects. The beam-beam spectrum showed strong nonlinear resonant phenomena. Considering the nonlinearity, the coherent beam-beam tune shift was measured as a function of the bunch current. It was confirmed that the vertical beam-beam parameter estimated from the coherent beam-beam tune shift agreed with a value obtained from a bunch-by-bunch luminosity monitor. The estimated vertical beam-beam parameter was saturated on a level of about 0.04, which is called a beam-beam limit. We found that the bunch current corresponding to the beam-beam limit was far below the bunch current used in the usual operation.
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Slides
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| WEPP035 |
Study of Beam-beam Issue for KEKB Crab Crossing
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2596 |
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- K. Ohmi, J. W. Flanagan, Y. Funakoshi, N. Iida, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, Y. Seimiya
KEK, Ibaraki
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A short lifetime at collision is one of the limits on luminosity performance at KEKB in crab crossing mode. The beam-beam halo was evaluated via simulation. The beam lifetime and profile were measured for various beam conditions, vertical emittances, tunes and collision offsets. We discuss why the lifetime is shortened by the beam-beam interaction.
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