| Paper |
Title |
Page |
| TUPC040 |
Measurements of Beam-beam Kick using a Gated Beam-position Monitor under Crabbing Collision at KEKB
|
1143 |
| |
- T. Ieiri, H. Fukuma, Y. Funakoshi, M. Masuzawa, K. Ohmi, M. Tobiyama
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. A gated beam-position monitor is a tool to measure the beam-beam effects. A beam-beam kick curve was measured by comparing the beam position between colliding and non-colliding bunches, while shifting the beam orbit at the interaction point (IP). An effective horizontal beam size at the IP was obtained from a linear part of the beam-beam kick around the central orbit. The estimated beam size agreed with a calculated value including the dynamic effects. It was confirmed that the effective horizontal beam size was reduced by the crabbing collision, as expected from a calculation with a rigid Gaussian model. When a horizontal orbit offset was larger than a beam size, however, we found that the measured beam-beam kick curve deviated from calculated values using the Gaussian model. The result suggests that the beam profile might enlarge horizontally in the peripheral part.
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| WEXG01 |
Performance of KEKB with Crab Cavities
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1893 |
| |
- Y. Funakoshi
KEK, Ibaraki
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20 years after they were initially proposed, in February 2007 crab cavities are for the first time installed in an operating collider, KEKB. The commissioning of KEKB with crab cavities is presented, and the performance of the collider is compared to the performance without crab cavities. Lessons learned from the operation with such cavities for future projects are discussed.
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Slides
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| WEPP035 |
Study of Beam-beam Issue for KEKB Crab Crossing
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2596 |
| |
- 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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