Electro-optic longitudinal electron beam diagnostic at SDL

The linac at the NSLS Source Development Lab (SDL) provides a high brightness electron beam for the DUV-FEL project with subpicosecond bunch length and several hundred Amperes peak current by means of a photoinjector and a magnetic bunch compressor. Previous diagnostics of the longitudinal bunch dynamics relied on the rf zero-phasing method and measurements of CTR spectra. In order to have a fast and nonintercepting longitudinal diagnostic available, the electro-optic measurement technique has been implemented with its major component, a synchronized 100 fs Ti:sapphire laser coaligned with the electron beam, already in place as a seed for the FEL. The theoretical temporal resolution for a 100 μm thick ZnTe crystal is limited to about 200 fs and the signal contrast to more than 1%. We present preliminary results of multishot scanning measurements and the single-shot diagnostics of the bunch shape as well as its application as a rf-laser jitter monitor.