1. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LCLS Drive Laser Timing Stability Measurements XFEL Short Bunch Measurement and Timing Workshop

2. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LCLS Machine Stability Tolerance Budget X-band X-X-X-X- RMS tolerance budget for <12% rms peak-current jitter or <0.1% rms final e− energy jitter. All tolerances are rms levels and the voltage and phase tolerances per klystron for L2 and L3 are  Nk larger, assuming uncorrelated errors, where Nk is the number of klystrons per linac. P. Emma 800fS rms

3. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LINAC RF and Timing System PEP PHASE SHIFT ON MAIN DRIVE LINEMDL RF with TIMING Pulse – Sync to DR Master Oscillator is located 1.3 miles from LCLS Injector 1.3 Miles to LCLS Injector

4. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Linac Phase Reference System Main Drive Line - 3 1/8 Rigid Coax Anchored to Concrete Floor Every Sector Phase Reference Line - Each Sector Independent 1/2 “ Heliax

5. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Linac Phase Reference System Main Drive Line 3 1/8 inch Rigid Coax with 30watts Length = 31 Sectors, 15.5 furlongs 2miles, 3km : Velocity = 0.98c Anchored at each sector next to coupler and expansion joint Purged with dry nitrogen Phase Length Range 100  S/Year Phase Length Range 40  S/Day Accuracy Based on SLC Fudge Factor 0.5  S/Sector Total Variation 0.2  S rms / Sector Phase Reference Line ½ inch Heliax Cable with 1.2 Watts Phase Reference for 8 PADs (Klystrons) in the sector Length = 1 Sector, 0.5 furlongs, 332ft, 400k  S in ½” Heliax Temperature Coefficient 4ppm/  C Waveguide Water  T = 0.1  C rms 85% of the cable is regulated to 0.1  C rms 15% may see variations of 2  C rms Average Temperature Variation = 0.4  C rms  = 0.64  S rms

6. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Phase Noise of SLAC Main Drive Line Old Oscillators Noise Floor of About -120dBc/38Hz = -136dBc/Hz = 120fS rms Jitter in 5MHz BW

7. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Phase Noise of SLAC Main Drive Line New Oscillators Noise Floor of About -133dBc/38Hz = -149dBc/Hz < 60fS rms Jitter in 5MHz BW New Oscillators Have a noise floor of -157dBc/Hz @ 476MHz 11fS rms Jitter in 5MHz BW or 31fS rms Jitter in 40MHz BW Above plots give upper limits, much of which could be from measurement system

8. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 SLAC Linac RF The PAD measures phase noise between the reference RF and the high power system. The beam sees 3.5uS of RF from SLED.

9. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LINAC RF MEETS ALL LCLS SPECIFICATIONS for 2 Seconds when running well Amplitude fast time plots show pulse to pulse variation at 30Hz. Standard deviation in percent of average amplitude over 2 seconds are 0.026% for 22-6 and 0.036% for 22-7. Phase fast time plots show pulse to pulse variation at 30Hz. Standard deviation in degrees of 2856MHz over 2 seconds for the three stations are 0.037  for 22-6 and 0.057  for 22-7.

10. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LINAC RF is Out of LCLS Specs in 1 Minute 14 minutes data taken using the SCP correlation plot Note that 22-6 and 22-7 are correlated in phase and amplitude Amplitude 22-6 0.20%pp Amplitude 22-7 0.43%pp Phase 22-6 1.2 Deg pp Phase 22-7 1.2 Deg pp

11. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Phase as Seen by Electron is Difficult to Measure Accelerator Water Temperature Effects on SLED Phase [1 ] [1 ] The tuning angle of the SLED cavity goes as:  = tan -1 (2Q L  T), Where  T =  L/L = -  /  Q L = 17000  = 10 -5 /  F Thermal expansion of copper.  =tan -1 (0.34  T)Where  T is in  F. For small  T,  (  S)= 20  T(  F) The relation between the tuning angle  and the measured output phase of the klystron  varies with the time after PSK with about the following relation:  /  = 0.35just after PSK  (  S)= 7  T(  F)  /  = 0.50800nS after PSK  (  S)= 10  T(  F)  /  T~ +8.5  S /  F for SLED Cavity Accelerator Water Temperature Effects on the Accelerator Phase [2] [2] The phase change of the structure goes as follows:  =   f Where  = phase through structure  = Angular frequency  f = Filling time of structure  =   f =  /  x  f  /  = -  L/L = -  T = -10 -5  T /  F for copper  = -10 -5  T /  F  2  2856MHz  0.84  S = -0.15  T rad/  F = -8.6  T  S /  F  /  T = -8.6  S /  F for Accelerator Structure Water / Accelerator Temperature Variation is 0.1  F rms  through structure is 0.86  F rms [1] [1] Info from D. Farkas [2] [2] Info from P. Wilson

12. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Phase as Seen by Electron is Difficult to Measure Accelerator Water Temperature Effects on the Phase Through the Accelerator -8.6  S /  F SLAC Linac Accelerator Water Temperatures  T<.08  Frms Phase Variations Input to Output of Accelerator > 0.5ºS-Band rms Single Measurement Can’t Determine the Phase the Beam Sees Passing Through the Structure to LCLS Specifications Feedback on Input Phase, Output Phase, Temperature, Beam Based Parameters (Energy and Bunch Length) is Required to Meet LCLS Specifications Accelerator Water Temperature Effects on the Phase Through the Accelerator -8.6  S /  F SLAC Linac Accelerator Water Temperatures  T<.08  Frms Phase Variations Input to Output of Accelerator > 0.5ºS-Band rms Single Measurement Can’t Determine the Phase the Beam Sees Passing Through the Structure to LCLS Specifications Feedback on Input Phase, Output Phase, Temperature, Beam Based Parameters (Energy and Bunch Length) is Required to Meet LCLS Specifications

13. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LINAC SECTOR 20 – LCLS INJECTOR RF Stability < 50fS rms : Timing/Trigger Stability 30pS rms

14. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LCLS RF System – Sector 20 Layout 100ft ½” Heliax = 0.3ºS/ºF Tunnel Temperature < 0.1deg F rms

15. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 SPPS Laser Phase Noise Measurement R. Akre, A. Cavalieri

16. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 SPPS Laser Phase Noise Measurements Phase Noise of Output of Oscillator with Respect to Input Measurement done at 2856MHz with External Diode R. Akre, A. Cavalieri

17. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 SPPS Laser Phase Jump Tracking R. Akre, A. Cavalieri

18. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 SPPS Laser Phase Jump Tracking 0.25pS pk Square Wave Laser Phase Error – Output Phase to Input Reference - Modulated with 1 Hz Square Wave

19. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 SPPS Laser Amplitude of Phase Transfer Function Phase Modulation placed on RF Reference and measured on Diode at Laser output. R. Akre, A. Cavalieri During the Blue part of the curve the modulation amplitude was reduced by 12dB to prevent laser from unlocking. Data taken 10/22/03 R. Akre, A. Cavalieri

20. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Linac Phase Stability Estimate Based on Energy Jitter in the Chicane SLAC Linac 1 GeV 30 GeV 30 GeV 9 GeV e  Energy (MeV) BPM  2  1/2  < 0.1 deg (100 fs)  E /E 0  0.06% P. Emma

21. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Jitter determination from Electro Optic sampling ErEr Principal of temporal-spatial correlation Line image camera polarizer analyzer EO xtal  seconds, 300 pulses:  z = 530 fs ± 56 fs rms  t = 300 fs rms single pulse A.Cavalieri P. Krejcik centroid width

22. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Electro-Optical Sampling 170 fs rms Single-Shot Timing Jitter (20 Shots) 200  m thick ZnTe crystal eeee Ti:Sapphire laser Adrian Cavalieri et al., U. Mich. <300 fs e  temporal information is encoded on transverse profile of laser beam

23. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 LCLS Phase Noise Associated Time Referenced to Beam Time LCLS LaserNeed to Measure 10uS to 1mS~200uS LCLS Gun1.1uS SLED / Accelerator 3.5uS Phase Detector (Existing)30nS Distribution System200nS 1km @ c-97%c=100nS Far Hall Trigger2uS 3km @ c-80%c=2uS TIME -3.5us SLED Starts to Fill -1.1uS Gun Starts to Fill -2uS Far Hall Trig RF Starts Trip Beam Time 0 Reference

24. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 Beam Trigger for User Facility Single Pulse with 30fS stability (1Hz to 3GHz BW) Tightest Noise Tolerance of LCLS Wide Bandwidth – Narrow Bandwidth ECL chips have 150pS rise times Low Phase Noise 30fS Stability today 10fS Stability tomorrow 1fS ??? Design Needs Input

25. R. Akre XFEL Short Bunch Measurement and Timingakre@slac.stanford.edu July 26, 2004 NO CONCLUSIONS