Compensationof the crossing angle with crab cavities at KEKB

Abstract

Crab cavities have been installed in the KEKB BFactory 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. Proceedings of PAC07,

RF Technologies for Future Colliders

“…The cavity had a special coaxial coupler to damp the fundamental mode and large beam pipes for suppressing HOMs. The cell had a squashed shape to split two deflecting modes and select one polarization [59]. The cavities successfully crabbed the KEKB bunches to provide head-on collisions in the detector.…”

Final Report for "Compact Crab Cavity Design"

“…Crab cavities are an emerging technological advancement that allows for increased luminosity on crossing beamlines in the interaction region, as illustrated in Figure 1 1 . First installed in the KEK accelerator 2 , crab cavities are now being designed for upgrades to existing accelerators, including the Large Hadron Collider (LHC), and are being integrated into planning for most new accelerators and accelerator planning studies, such as the Medium Energy Electron-Ion Collider (MEIC) under design at Jefferson Lab. The most recent design for the MEIC calls for 750 MHz crab cavities, but researchers are also considering 1500 MHz cavities.…”

Studies on BEPC upgrade from pretzel to double-ring

“…This indicates that beam-beam interaction with a large angle makes beam size blow-up and limits the achievable maximum beam-beam parameter and then luminosity. The crab cavity may turn crossing angle to head-on collision so that beam-beam parameter and luminosity can be enhanced [11]. High luminosity requires both electron and positron rings to be operated with a high current multi-bunch beams.…”