Development and Construction Status of the Beam Diagnostic System for XFEL/SPring-8

We report the design, performance, and installation of the beam diagnostic system of XFEL/SPring-8. The electron beam bunches of the XFEL accelerator are compressed from 1 ns to 30 fs by bunch compressors without emittance growth and the peak-current fluctuation of the accelerator directly causes SASE fluctuation. To maintain stable bunch compression process, the accelerator requires rf cavity beam-position monitors (BPM) with 100 nm resolution, OTR screen monitors (SCM) with a few micro-meter resolution, fast beam current monitors (CT), and temporal structure measurement systems with resolution of under a picosecond. The performance of each instrument was tested at the SCSS test accelerator and was found to be sufficient for our requirement. To measure the temporal structure of the electron bunch, three types of measurement systems a streak camera, an EO sampling measurement, and a transverse deflecting cavity with a resolution of few-tens femtoseconds have been prepared. The streak camera and EO sampling show sub-picosecond resolution. The installation of these beam diagnostic systems to the XFEL accelerator is well under way.