| Paper | Title | Page |
|---|---|---|
| WEPC28 | Timing and Synchronization at the LCLS | 373 |
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| Timing and synchronization in the LCLS is a three tier process: At level 1 an event generator broadcasts timing fiducials to event receivers over a fiber network. Hardware and software triggers are created in the event receiver according to the digital pattern broadcast at 360 Hz by the event generator. Beam synchronous data acquisition driven by these triggers allows time-stamped acquisition of all diagnostic devices simultaneously on every pulse. Timing fiducials are phase synchronized to the low level RF reference system with 10 ps precision. Level 2 synchronization ensures that individual klystrons powering gun and accelerating sections remain within a few tenths of a degree S-band to the phase reference distribution scheme. The gun laser system is also phase locked to this reference to within 0.5 ps. Level 3 provides synchronization at the 10 fs level between the electron beam and pump-probe laser systems in the end station experiments. This will be achieved with electro-optic sampling of the electron bunch and by synchronizing the laser systems over a stabilized fiber distribution system. A fiber stabilization scheme is currently under test at Lawrence Berkeley Laboratory. |