Next: Final focus Quadrupole Magnet
The design principle is the smallest crossing angle as possible because of the
highest luminosity without a crab cavity. The present angle of 4mrad is
limited by synchrotron radiation background emitted from collimated beam. If
we use a crab cavity, the luminosity increases by about 40%.
SLAC assumes the perfect performance for a crab cavity, then the crossing angle
is mrad for easier extraction of disrupted beams, whose magnitude is
limited by a 4 Tesla (detector-)solenoidal field.
Phase stability of the crab cavity must be less than , thus we need
a prototype cavity.
Since KEK-B factory uses a crab cavity, it may be the prototype(?).