XFEL 2004 at SLAC m. ferianis Synchronization and phase monitoring: recent results at ELETTRA Synchronization experiment using light sources currently available at Elettra Streak camera measurements CW Phase measurements Status of the “light-to-light” jitter monitor Single event phase measurement Mario Ferianis, Miltcho Danailov SINCROTRONE TRIESTE, Italy

XFEL 2004 at SLAC m. ferianis Radiation sources currently available at Elettra Sources presently available at ELETTRA: –Bending Magnet S12.2 (diagnostic beam line)  FWHM =30ps t REP  1MHz –Storage Ring - FEL  FWHM =8pst REP  4MHz, –Table top fs-lasers: Ti:Sa and Cr:LiSaf  FWHM  110fst REP  100MHz The SR-FEL is “naturally” synchronized to ELETTRA The table-top lasers may be locked to an external RF

XFEL 2004 at SLAC m. ferianis Synchronization experiment of a fs Laser to Elettra Sources Phase Detector Power Splitter LP filter Piezo driver Laser cavity Laser IN Reference IN Piezo actuator f REP2 = MHz f REF = MHz Synchrotron Radiation 22  N Unit Synchro- scan Streak Camera Streak Camera Timing system f S-SCAN =250MHz Power Splitter Laser Timing Stabilizer from Storage Ring RF generator f RF = MHz Power Splitter Divide-by-6 Unit

XFEL 2004 at SLAC m. ferianis View of the Profile Monitor laboratory with the Cr:LiSAF laser and the Streak Camera

XFEL 2004 at SLAC m. ferianis laser 2ns 10ns Streak Camera acquisition: Multi Bunch (2ns spacing) f REP1 =f RF  5 = MHz

XFEL 2004 at SLAC m. ferianis 880ps 864ns: 1 ELETTRA revolution 18 laser pulses 4 Bunch beam (216ns/bunch) + (12ns) 12ns 440ps f REP2 =f RF  6 = MHz

XFEL 2004 at SLAC m. ferianis 5 accumulated acquisitions Laser phase oscillations due to external kick Elettra 4 bunch beam 180ps 880ps 69ms

XFEL 2004 at SLAC m. ferianis All three sources FEL staff courtesy FEL macropulses CR:LiSAF The “old, good ELETTRA” 4.6MHz 6.7ms

XFEL 2004 at SLAC m. ferianis Phase Detector AD8302 (0  2.7GHz) Analog Devices  EX-OR Low-pass filter Vector analyser on a chip

XFEL 2004 at SLAC m. ferianis V phase vs.  F tot =100kHz   TOT =0.135deg  tot =0.135deg;  step =13.5mdeg  V STEP =0.135mV  min =0.187ps (  step /2)  min =6.25fs

XFEL 2004 at SLAC m. ferianis Comparison of two phase measurements AD 8302 Phase Detector Power Splitter Ceramic Band Pass LC filter Piezo driver Laser cavity Laser IN Reference IN Piezo actuator f REP2 = MHz Power Splitter Laser Timing Stabilizer Photo diode R&S generator A B 1) V PHASE Spectrum Analyzer HP3589 Digital Oscilloscope TEK ) Phase OUT

XFEL 2004 at SLAC m. ferianis Spectra of phase noise of the laser MHz CLX 1100 Phase OUTPUT AD8302 V phase

XFEL 2004 at SLAC m. ferianis Locked laser damping time to an external kick AD8302 V phase 100mV/div CLX phase OUT 20mV/div 300ms

XFEL 2004 at SLAC m. ferianis Experiment set-up in the SRPM hutch Phase Detector Power Splitter LP filter Piezo driver Laser cavity Laser IN Reference IN Piezo actuator f REP2 = MHz f REF = MHz Synchrotron Radiation Band pass filter 18 th harmonic Direct light-to-light on-line jitter measurement Sub-ps Phase comparator 22  N Unit Synchro- scan Streak Camera Streak Camera Timing system f S-SCAN =250MHz Power Splitter Laser Timing Stabilizer from Storage Ring RF generator f RF = MHz Power Splitter Divide-by-6 Unit

XFEL 2004 at SLAC m. ferianis Bandpass filter response to 4 Bunch beam, f 0 =83.275MHz, BW 6.5MHz.

XFEL 2004 at SLAC m. ferianis AD8302 phase measurement: 6.5MHz filter output vs. reference (83.275MHz)  V=330mV  33deg

XFEL 2004 at SLAC m. ferianis Narrowband (BW=2.5MHz) bandpass filter

XFEL 2004 at SLAC m. ferianis FERMI Phase Measurements The term “Phase measurement” generally refers to measuring the phase of a signal w.r.t. a reference. Rigorously, we can speak about phase when dealing with sinusoidal signals, eventually sinusoidal bursts. For FERMI applications, two different “phase” measurements* are needed: –sinusoidal to reference (CW/CW burst measurement) –pulse to reference (single event measurement) For pulsed signals, the phase difference can be defined as the time interval bewteen pulse arrival and next zero crossing of the reference signal. The most critical measurement is the second one due to: –required (sub-) ps resolution –ultra short pulses of limited amplitude (low energy signals) –low repetition rate (1 to 100Hz) * APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation s.r.l.

XFEL 2004 at SLAC m. ferianis Proposed scheme for single event phase measurement Pulse stretcher Beam pulse signal Reference signal “0” Xing detector (low jitter) Hold off Time interpolator (SiGe logic) Pulse stretcher “0” Xing detector (low jitter) APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation

XFEL 2004 at SLAC m. ferianis Zero X-ing detector prototype tests with Pulse Generator: t PULSE =300ps; A PULSE PK-PK =90mV; f REP =10kHz TRIGGER CSA803C Sampling Scope BW=20GHz INPUT HP8131A 500MHz Pulse Generator 10mV/div 100ps/div Jitter RMS =1. 37ps TRIGGER CSA803C Sampling Scope BW=20GHz INPUT HP8131A 500MHz Pulse Generator “0” X-ing detector INOUT under test 100mV/div 100ps/div Jitter RMS =1.94ps A pk-pk = 600mV*10 (20dB att) =6V APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation s.r.l.

XFEL 2004 at SLAC m. ferianis t RISE =18ps t PULSE =30ps A PULSEpk-pk =250mV Zero X-ing detector prototype f REP =10Hz fs laser + Pockels Cell + 25GHz Photodiode New Focus Photo Diode BW=25GHz “0” Xing detector under test IN OUT TEK Real time Scope TRIGGER CH1 BW=1GHz CH2 Cr:LiSAF fs laser Pockels Cell HV driver SPLITTER Amplifier 7GHz Pulse generator -10dB 2Vpk-pk *3.17=6.3V APL - Dip. Elettronica ed Informatica, Trieste University and AllTEK Innovation

XFEL 2004 at SLAC m. ferianis Future work To complete direct light-to-light phase measurements in 4B mode –Bending Magnet to external fs laser –Bending Magnet to SR-FEL –SR-FEL phase during Q-switch w.r.t. a non modulated RF (?) To complete jitter reduction work in the Profile Monitor hutch To implement phase measurement at low rep rate –10Hz i.e. FERMI To characterise laser jitter in fiber optic transmission To study the feasibiltiy of an in-house improved version of phase locking system (timing stabilizer)