Li, Z.

Paper	Title	Page
WG524	Cavity BPMs for LCLS
	P. Krejcik, Z. Li, S. Smith, T. Straumann SLAC, Menlo Park, California R. M. Lill ANL, Argonne, Illinois
	Stabilization and alignment of the beam trajectory in the LCLS undulator requires single-shot measurement of the beam position with a resolution of 1 micron or better at a charge per bunch of 200 pC. A stripline beam position monitor is limited by signal to noise at this resolution since it relies on determining the precise difference between the signals from two opposite strips. In our high Q cavity beam position monitor we selectively look at the signal from a transverse mode excited by an off-axis beam, which grows in amplitude proportionally with beam offset. The LCLS undulator and launch region will be equipped with 40 X-band cavity BPMS. A mixer is located beside each BPM and the IF is transmitted via cable to surface buildings housing the digitizer electronics. The design choices effecting the construction and layout of the system will be discussed along with prototype tests and installation plans for the LCLS.
	Slides