Status of the Lcls Experiment Timing System*

SLAC, Menlo Park, CA 94309, USA Abstract X-ray / optical laser pump probe experiments are used for a significant fraction of the scientific work performed at LCLS.[1] The experimental laser systems are locked to the timing of the electron beam through a combination of RF and optical fiber based systems. The remaining ~100 femtosecond RMS jitter of the X-rays relative to the optical laser is measured shot-to-shot by both a RF timing detector, and by direct X-ray to optical cross-correlation, and the result is used to correct the experiment timing to 10s of femtoseconds. We present the present status of the system and plans for future upgrades.