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.