1. Updates on RF synchronization and fast trigger distribution A. Butterworth, H. Damerau, W. Hofle Acknowledgements: T. Bohl, S. Doebert, I. Kozsar, J. Molendijk, S. Rey 19 May 2015

2. Outline Introduction Updated layout Laser phase locked loop RF signals and beam synchronous triggers Synchronization with SPS Hardware and fast trigger destinations Summary

3. Introduction SPS RF synchronization with laser – Optical fiber link BA3/BA4 and dividers for RF distribution  Needed for first proton beam extraction to AWAKE System to synchronize the arrival in the plasma chamber of three beams – Proton bunch from SPS – Laser pulse in AWAKE – Electron bunch from electron source AWAKE repetition rate (10 Hz) not synchronous with SPS cycle – Transfer timing variable in a 100 ms window, unlike other transfers at CERN Precision requirements – RF master clock @ 3GHz locked to GPS disciplined 10 MHz reference – Laser locking to RF master, jitter (1 Hz – 10 MHz) lower than 0.25 ps rms – Electron bunch arrival to LASER pulse, jitter (1 Hz – 10 MHz) lower than 1 ps rms – SPS proton bunch arrival to Laser pulse, jitter (1Hz – 10 MHz) lower than 10 ps rms Including contribution of fiber link BA3 (RF)  AWAKE of no more than 1 ps rms 3

4. Laser locked-loop, AWAKE reference (TSG40) 4 “Fiber Ring Oscillator” (Comb) F rep =88.173502 MHz 1550 nm 780 nm (doubler) Laser head PD 10 GHz 3 GHz filter LPNA MenloSystems analog FB (PID) control box Piezo drive 3 GHz low phase noise GPS 10 MHz PD 10 GHz 3 GHz filter LPNA  Photo diode 88 MHz filter LPNA 88.173502 MHz (laser) 2997.8991 MHz (laser) 2997.8991 MHz (reference) 10 MHz AWAKE  Preferred baseline: laser phase locked loop based on commercial elements  No layout change since February TB  prepare technical specification LPNA: Low Phase Noise Amplifier

5. RF Signal distribution (TSG40) 88.173502 MHz (laser) 2997.8991 MHz (reference) 2 1 17 1 10164 1 870 1 Reset logic f rep 9.97 Hz Frac. div.  25/11 f c 8.68 kHz 88.173502 MHz (laser synchronous) f RF, SPS 200.394 MHz VME trigger unit Laser trigger prepulse f rep Warning AWAKE Beam with 2 nd f rep 1498.9495 MHz 2997.8991 MHz electron beam Synchronization (CTRV) AWAKE Technical Board February 2015

6. Separate board Main divider board RF Signal distribution (TSG40) 6 88.173502 MHz (laser) 2997.8991 MHz (reference)  Layout frozen, few changes since February TB  Precision triggers based on counters of 2f ML = 176.3 MHz and 10 ns fine delay  Cable event from SPS to gate laser amplifier and arm fast trigger counters 17 1 2 1 5082 1 870 1 Reset logic f rep 9.97 Hz Frac. div.  25/11 f c 8.68 kHz 44.086751 MHz (for CTRVs) f RF, SPS 200.394 MHz VME trigger unit Precision trigger(s) f rep 2997.8991 MHz electron LLRF Synchronization (CTRV) 176.347004 MHz CTRV trigger unit Laser trigger/gate Timing telegram 2 1 88.173502 MHz (laser synchronous) CTRV trigger unit Timing telegram SPS AWAKE

7. Timing telegram Synchronization of proton beam in SPS (BA3/CCR) 7 CTRV trigger unit SPS ready for transfer Timing telegram CTRV trigger unit 1 kHz f rep 1 kHz CTRV trigger unit 1 kHz VME trigger unit f rep f RF, SPS VME trigger unit f rep f RF, SPS VME trigger unit f rep f RF, SPS CBCM 1 st f rep pulse after ‘ready for transfer’, TREP1 Warning AWAKE Extraction warnings: -180 ms, -80 ms, -50 ms, -20 ms TREP1 + 1..2 ms Start bunch rotation Extraction warning RF Extraction Arm fast trigger counters TREP1 + 1..2 ms 1.Arrival on flat-top + 500 ms for RF synchronization  Beam synchronous with f c  SPS ready for transfer 2.Wait 0...100 ms for next f rep pulse + delay of some milliseconds  Trigger ejection sequence of central timing  Arm fast trigger counters 3.Central timing generates arm pulse for fast triggers in AWAKE and extraction warnings 4.Fast trigger counters on f RF,SPS started with next f rep pulse 5.Precision triggers at and close to extraction 1.3. 4.2.5. ~100 ms (1/f rep ) Extraction f rep t TREP1 TREP2TREP3

8. Distributed frequencies (from TSG40) SignalFrequencyComment AWAKE 10 MHz GPS ref.10 MHzAbsolute GPS reference RF reference e-beam, f eRF 2997.899068 MHzSynthesized from 10 MHz RF for triggers, 2f ML 176.347004 MHzFast trigger counters (VTU) Mode locker frequency, f ML 88.173502 MHzf ML = f eRF /34 RF for slow triggers44.086751 MHzSlow trigger counters (CTRV) 200 MHz RF SPS200.3943227 MHzf ML · 25/11 for RF synchronization Common frequency, f c 8.675078906 kHzf ML · 25/(11 · 5 · 4620) = f ML /10164 Laser repetition rate, f rep 9.971355064 Hzf ML · 25/(11 · 5 · 4620 · 870) = f c /870 SignalComment Fast triggers (VTU)Last f c pulse before extraction + m · 2f ML + 0…10 ns, ~10 ps jitter Slow triggers (CTRV)Last f c pulse before extraction + n · f ML /2 a) RF signals from AWAKE: b) Triggers in distributed in AWAKE c) Unsynchronized timings provided by BE-CO: Extraction -180 ms, -80 ms, -50 ms, -20 ms

9. Precision triggers Low jitter (~10 ps) pulses individually programmable at virtually any moment with respect to arrival of beams (before and after)  Independent settings for each fast trigger  Settings to compensate cable delays Possibility to generate triggers for tests in the absence of  Proton beam (decoupled from SPS)  Laser oscillator Programmable counters + fine delays:  Last f c pulse before extraction + m · 2f ML + 0…10 ns, ~10 ps jitter Should only be used if high precision/low jitter needed (1 pulse/board)  Standard timing (e.g. counting f ML /2), 8 channels/board  Existing VME trigger unit from LHC (or newer Linac4 hardware)

10. Hardware requirements Synchronization and distribution SPS  AWAKE  Copy of synchronization SPS  LHC  Hardware exists, possibly production of further modules  Proton bunch from SPS Compensated optical fibre link  New development, CERN fellow started this month RF divider and distribution  Conceptual layout completed: divider board + separate fractional divider f RF,SPS  New developments, additional man-power identified Fast trigger units  Hardware exists from LHC/Linac4  Dedicated production series for AWAKE

11. Distribution of RF signals and fast triggers DestinationContact personsComment Electron LLRFS. Doebert, H. Damerau, W. Hofle RF and triggers Laser amplifier gatingJ. Moody, P. Muggli Gating pulse only Streak camera experiment and fast acquisition P. Muggli, K. Rieger ~12 fast triggers in total Streak camera BIB. Biskup, S. Mazzoni Electron beam diagnosticsL. Jensen, L. Soby, V. Verzilov RF and triggers RF signals and triggers to CO front-ends I. Kozsar, J.-C. Bau Mainly 44.1 MHz and 10 Hz  Request for RF cabling (DIC) submitted  Flexibility which signal connected to which cable  Additional patch panels from TSG40 (~20 RF connectors)

12. Summary and outlook Few changes to conceptual layout since February TB  Laser-locked loop  Commercial components  RF Distribution and optical fiber links  CERN  Conceptual RF distribution layout frozen Survey of RF signals and fast triggers needs  List of destinations and cabling request  Please let us now as soon as possible if signal missing Next steps: Technical specification for laser-locked loop Electronics design of stabilized fiber link  Fellow started this month Electronics design of divider board for RF distribution

13. Spare slides