UED at ASTA: LLRF and triggers Need < 100 fs jitter Currently we measure > 500 fs RMS phase noise in 10 Hz to 10 MHz bandwidth at 476 MHz Excessive phase noise is due to the dirty reference from LCLS (which conveniently provides AC power fiducials for triggering) Suggested improvements: – Import clean 476 MHz from linac – Local source with local trigger generation

Courtesy J. Dusatko

Fiber from LCLS

Clean 119 MHz from LI30 Relic of E-144 FFTB experiment: TW laser synced to beam time with 0.5 ps stability – Recommission LI30 RF fiber optic diode laser transmitter (30 mW laser hazard) – Adapt to standard SLC fiber – Fiber patch LI30 to B44 – Relocate the receiver (from B407) No need for a new timing system!

Local source, local triggers Locked 562 fsec RMS jitter Unlocked 50 fsec RMS jitter

Local source, local triggers The unlocked PLL has a relatively clean 476 MHz source Still need triggers: Rebuild/borrow spare HW to reproduce LCLS fiducial generation in the klystron test lab

Courtesy J. Dusatko

LINAC triggers

Courtesy J. Dusatko