Brief summary of discussion on crab cavity, 22.09.2006

Participating: Rama Calaga, Tom Taylor, Rogelio Tomas, Frank Zimmermann

The old EPAC paper contained some error. The minimum crossing angle with separate quadrupole channels is 4-5 mrad, rather than 2 mrad. A crossing angle of 8 mrad is certainly feasible (and expensive). A stabilizing wedge of “conical” shape likely needs to be inserted between the two sides of the magnet. Fro crossing angles below 2 mrad, the standard solution of a single joint quadrupole can be employed.

Tom suggested an alterantive hybrid solution, where the first quadrupole is joint and the later ones split, but this faces problems with the order of focusing and defocusing magnets, since the relative polarity seen by the two beams is opposite for the joint and the separate magnets.