DESIGN OF CAVITY BPM PICKUPS FOR SWISSFEL

SwissFEL is a 0.1nm hard X-ray Free Electron Laser being built at PSI. A photocathode gun, S-band injector and C-band linac provide 2 bunches at 28ns spacing, 10200pC charge range, 100Hz repetition rate, and 5.8GeV maximum energy. A fast distribution kicker will provide one bunch each to one hard X-ray and one soft X-ray undulator line. For linac and undulators, first prototypes of dual-resonator cavity BPM pickups have been designed and one undulator prototype has been fabricated. The pickups were optimized for low charge and short bunch spacing in the linac. Design considerations, simulation and first test results will be reported.