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- Y. Morita, K. Akai, K. Ebihara, T. Furuya, K. Hara, T. Honma, K. Hosoyama, A. Kabe, Y. Kojima, S. Mitsunobu, H. Nakai, K. Nakanishi, M. Ono, Y. Yamamoto
KEK, Ibaraki
- T. Kanekiyo
Hitachi Ltd., Hitachi Research Laboratory, Ibaraki-ken
- K. Okubo, K. Sennyu
MHI, Kobe
- M. M. Rahman
University of Chittagong, Chittagong
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Tow superconducting crab cavities, witch will be installed in the KEKB accelerator, is being assembled. The KEKB (KEK B-factory) is a double-ring, asymmetric-energy, high luminosity electron-positron colliding accelerator with a finite angle beam crossing. A purpose of the crab cavities is to deflect the beam-bunch with time-varying RF fields, and to provide the head-on collision at the interaction point (crab crossing scheme). The head-on collision will drastically increase luminosity. The crab cavity is required to have high RF fields (kick voltage) to provide beam-bunch deflection. This mode (crab mode, 509 MHz) is not the lowest order mode (LOM) of the cavity. In order to damp the LOM as well as the HOMs, a coaxial coupler is attached along the beam pipe. Two crab cavities have been fabricated and tested in a vertical cryostat. These cavities have already achieved the required kick voltage. One cavity was recently tested with high RF power in a cryomodule. After some conditioning, this cavity has achieved the required kick voltage. The test revealed some modifications were needed. After improvements, the cavity will be ready for installation.
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