Synchronization and phase monitoring recent results at ELETTRA

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 S 12. 2 (diagnostic beam line) • t. FWHM=30 ps t. REP 1 MHz – Storage Ring - FEL t. FWHM=8 ps t. REP 4 MHz, – Table top fs-lasers: Ti: Sa and Cr: Li. Saf • t. FWHM 110 fs t. REP 100 MHz • • 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 Synchrotron Radiation pulses @4. 626 MHz Streak Camera Timing system from Storage Ring RF generator f. RF=499. 654 MHz 2 Power Splitter f. S-SCAN=250 MHz N Unit Synchroscan Streak Camera Divide-by-6 Unit f. REF= 83. 2756 MHz Phase Detector Power Splitter Reference IN Laser Timing Stabilizer f. REP 2=83. 2756 MHz LP filter Piezo driver Piezo actuator Laser cavity XFEL 2004 at SLAC m. ferianis

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

Streak Camera acquisition: Multi Bunch (2 ns spacing) beam+laser @99. 93 MHz 2 ns 10 ns laser f. REP 1=f. RF 5 = 99. 9308 MHz XFEL 2004 at SLAC m. ferianis

4 Bunch beam (216 ns/bunch) + laser@83. 275 MHz (12 ns) f. REP 2 =f. RF 6 = 83. 2756 MHz 880 ps 12 ns 18 laser 12 ns pulses 864 ns: 1 ELETTRA revolution 440 ps XFEL 2004 at SLAC m. ferianis

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

All three sources CR: Li. SAF trace @83 MHz 6. 7 ms FEL macropulses FEL staff courtesy XFEL 2004 at SLAC The “old, good ELETTRA” 4 bunch @ 4. 6 MHz m. ferianis

Phase Detector AD 8302 (0 2. 7 GHz) Analog Devices Vector analyser on a chip EX-OR XFEL 2004 at SLAC Low-pass filter m. ferianis

Vphase vs. frequency @100 MHz: DFtot=100 k. Hz DFTOT=0. 135 deg DFtot=0. 135 deg; DFstep=13. 5 mdeg 1 deg@100 MHz =27. 7 ps; DTmin=0. 187 ps (DTstep /2) 1 deg@3 GHz =0. 926 ps; DTmin=6. 25 fs DVSTEP=0. 135 m. V XFEL 2004 at SLAC m. ferianis

Comparison of two phase measurements R&S generator Power Splitter Reference IN Laser Timing Stabilizer Spectrum Analyzer HP 3589 A 1) V PHASE AD 8302 Phase Detector B Laser IN Ceramic Band Pass LC filter Power Splitter 2) Phase OUT Piezo driver Digital Oscilloscope TEK 7104 Photo diode Laser cavity f. REP 2=83. 2705 MHz Piezo actuator XFEL 2004 at SLAC m. ferianis

Spectra of phase noise of the laser locked @ 83. 2705 MHz AD 8302 Vphase CLX 1100 Phase OUTPUT XFEL 2004 at SLAC m. ferianis

Locked laser damping time to an external kick AD 8302 Vphase 100 m. V/div 300 ms CLX phase OUT 20 m. V/div XFEL 2004 at SLAC m. ferianis

Experiment set-up in the SRPM hutch Synchrotron Radiation pulses @4. 626 MHz Streak Camera Timing system from Storage Ring RF generator f. RF=499. 654 MHz 2 Power Splitter f. S-SCAN=250 MHz N Unit Synchroscan Streak Camera Divide-by-6 Unit f. REF= 83. 2756 MHz Phase Detector Power Splitter Sub-ps Phase comparator Power Splitter Reference IN Laser IN Direct light-to-light on-line jitter measurement Laser Timing Stabilizer f. REP 2=83. 2756 MHz LP filter Piezo driver Piezo actuator Laser cavity XFEL 2004 at SLAC Band pass filter 18 th harmonic m. ferianis

Bandpass filter response to 4 Bunch beam, f 0=83. 275 MHz, BW 6. 5 MHz. XFEL 2004 at SLAC m. ferianis

AD 8302 phase measurement: 6. 5 MHz filter output vs. reference (83. 275 MHz) DV=330 m. V 33 deg XFEL 2004 at SLAC m. ferianis

Narrowband (BW=2. 5 MHz) 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 100 Hz) * APL - Dip. Elettronica ed Informatica, Trieste University and All. TEK Innovation s. r. l. XFEL 2004 at SLAC m. ferianis

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

Zero X-ing detector prototype tests with Pulse Generator: t. PULSE=300 ps; APULSE PK-PK=90 m. V; f. REP=10 k. Hz HP 8131 A 500 MHz Pulse Generator 10 m. V/div 100 ps/div “ 0” X-ing detector IN OUT under test TRIGGER 100 m. V/div 100 ps/div CSA 803 C Sampling Scope Apk-pk= 600 m. V*10 (20 d. B att) BW=20 GHz =6 V INPUT Jitter. RMS=1. 94 ps Jitter. RMS=1. 37 ps APL - Dip. Elettronica ed Informatica, Trieste University and All. TEK Innovation s. r. l. XFEL 2004 at SLAC m. ferianis

Zero X-ing detector prototype tests @ f. REP=10 Hz fs laser + Pockels Cell + 25 GHz Photodiode Cr: Li. SAF fs laser New Focus Pockels Photo Diode APL - Dip. Elettronica ed Informatica, Trieste University and All. TEK Innovation Cell BW=25 GHz Pulse generator HV driver SPLITTER TEK Real time Scope TRIGGER Amplifier 7 GHz t. RISE =18 ps t. PULSE =30 ps APULSEpk-pk=250 m. V CH 1 “ 0” Xing detector under test IN OUT BW=1 GHz -10 d. B CH 2 2 Vpk-pk *3. 17=6. 3 V XFEL 2004 at SLAC m. ferianis

Future work • To complete direct light-to-light phase measurements in 4 B 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 – 10 Hz 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) XFEL 2004 at SLAC m. ferianis