Nuclear Instruments and Methods in Physics Research A 499 (2003) 8–23 Beam-transport system of KEKB

The transport lines of the KEKB for positrons and electrons convey the beams separately from the injector linac to the KEKB rings. The length is about 500 m for each line. In order to make the maximum use of the existing tunnels and also to avoid interference with the AR, the beam lines took a serpentine course, resulting in a rather large curvature in the arcs. The consequences were a large number of bends in the arcs with high fields and also a large dispersion function and, thus, a large R56 component. The latter issue is crucial for the KEKB rings, since it results in a longer bunch length at injection. We adopted a special optics that reduces the R56 coefficient sufficiently. We have developed novel water-cooled ceramic chambers for kickers, eddy-current-type septum magnets for injection, and a beam-abort system for the rings. The present paper describes the design and current status of the beam lines, the injection system, and the beam-abort system