Experimental verification of velocity bunching via shot-by-shot measurement as S-band photoinjector and linac

We present an experimental verification of a bunch compression method named 'velocity bunching'. Velocity bunching based on the rectilinear compression uses a traveling wave accelerating tube as a compressor. The experiment was performed using an S-band photoinjector and a linac at the Nuclear Engineering Research Laboratory, University of Tokyo. The shot-by-shot bunch length was measured to be 0.5±0.1 ps (rms) on average using a femtosecond streak camera at a bunch charge of 1 nC. The experimental result is in good agreement with the PARMELA simulation result. (author)