PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 1 PH-ESE seminar, CERN, Universal Picosecond Timing System developed for the Facility for Antiproton and Ion Research (FAIR) Dr.-Ing. Michael Bousonville GSI 2005 – 2010 DESY 2010 – today

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 2 Overview Fundamental Concepts of Timing Systems –In General –The 4 Concepts –Comparison Universal Picosecond Timing System for FAIR –Design –Performance –Prospects Current Status of the System in FAIR

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 3 Fundamental Concepts of Timing Systems

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 4 Fundamental Concepts of Timing Systems In General all timing systems do the following: Master Oscillator a signal with φMφM fMfM and jMjM From a Reference Point 1 will be transmitted to 2 or more reference points: Reference Point 2 φ1φ1 j1j1 φ2φ2 j2j2 f2f2 f1f1 f: frequency φ: average phase j:phase jitter

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 5 Fundamental Concepts of Timing Systems In General the theoretical ideal case is: f M = f 1 = f 2 φ M = φ 1 = φ 2 j M = j 1 = j 2 = 0 and in real systems we have f M = f 1 = f 2 can be assumed as fulfilled φ M ≠ φ 1 ≠ φ 2 ≠ φ M Jitter > 0 Master Oscillator Reference Point 1 Reference Point 2 φ1φ1 j1j1 φ2φ2 j2j2 φMφM fMfM and jMjM f2f2 f1f1

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 6 Fundamental Concepts of Timing Systems In General Master Oscillator Reference Point 1 Reference Point 2 φ1φ1 j1j1 φ2φ2 j2j2 φMφM fMfM and jMjM the optimization is about: a)Long term drift |φ 1 - φ 2 | should be as constant as possible b)Short term jitter should be as low as possible

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 7 Fundamental Concepts of Timing Systems Long term drift Master Oscillator Reference Point 1 Reference Point 2 φ1φ1 j1j1 φ2φ2 j2j2 φMφM fMfM and jMjM The change of phase offset between 2 reference points in average over time Here are 2 approaches pursued 1. |φ 1 - φ 2 | ≈ constant Good for CW applications 2. φ 1 ≈ φ 2 Needed for processes that starts at a precise moment simultaneously Reasons for phase change 1. Change of transmission delays 2. Change of f M Delay 1 Delay 2

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 8 Fundamental Concepts of Timing Systems Measures against long term drift Master Oscillator Reference Point 1 Reference Point 2 φ1φ1 j1j1 φ2φ2 j2j2 φMφM fMfM and jMjM 1.Keep delays stable a) Passively: Phase stable components Temperature stabilisation of transmission system b) Actively: Measure and control the delay in the transmission system by a i. measurement instrument ii. delay unit 2.Keep frequency stable: GPS connection 3.Often a combination of these measures is used Delay 1 Delay 2

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 9 Fundamental Concepts of Timing Systems Short term jitter Master Oscillator Reference Point 1 Reference Point 2 φ1φ1 j1j1 φ2φ2 j2j2 φMφM fMfM and jMjM All systems try to minimize the jitter. Jitter → min Reasons for Jitter 1.Jitter of master oscillator 2.Additive noise due to signal transmission 3.Signal Interference (EMI) Countermeasures → Keep the reasons 1 to 3 low

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 10 Fundamental Concepts of Timing Systems Transmission Medium Since 1986 a trend can be observed to use standard single mode fibres (SMF) instead of coaxial cables for signal transmission. The advantages of SMFs are: 1.Very low attenuation of nm 2.Insensitive against electromagnetic disturbance 3.Low dispersion of nm 4.SMF in loose tube cables show a moderate TCD < 50 ps/(km·K) 5.Favourable price of 1 €/m 6.Standard component  good availability In the following, only systems with SMF will be considered.

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 11 Fundamental Concepts of Timing Systems Concept 1: Classic 1.E. Peschardt and J.P.H. Sladen – First systems using SMF 3.High optical attenuation of ca. 15 dB in both ways  SNR   Jitter 

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 12 Fundamental Concepts of Timing Systems Concept 2: Low Losses 1.T. Naito et. al. – First time WDM is used  Problem of high optical losses in concept 1 is reduced form 15 to 3 dB

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 13 Fundamental Concepts of Timing Systems Concept 3: Laser Based Synchronisation 1.H. Schlarb, A. Winter, F. Kärtner – More optical components A laser is the master oscillator  Short term jitter < 10 fs Properties at DESY: pulse width ≈ 200 fs; repetition rate 1.3 GHz/6 ≈ MHz Optical correlator for measuring the delay changes Master Laser Oscillator Link Stabilisation Unit Master RF Oscillator Optical Correlator Phase Shifter FRM Stabilized Pulse Train = Reference Signal Control Pulse Laser Application Optical Pulse Train

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 14 Fundamental Concepts of Timing Systems Concept 3 at XFEL Applications 1.Bunch Arrival Time Measurements 2.Laser-to-Laser Synchronization Synchronising of other pulse lasers 3.Laser-to-RF conversion Stabilizing the 1.3 GHz RF with the help of the optical reference signal  Cavity synchronisation Applications separate CDRs Peripheral Devices Synchronization-Hutch Racks Optical Table Master Laser Oscillator Free Space Distribution Link Box Fibre Cabling Link End Bunch Arrival Time Monitor Laser-to-Laser Synchronization Laser-to-RF Conversion Link Box Link End Link End Diagnostic Photo Injector Laser Gun, Cavities Air Conditioning System Measurement Equipment

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 15 Fundamental Concepts of Timing Systems Concept 3 at XFEL XFEL –Nomenklatur ZM1 – Jähnke / Stoye SASE positions by Tobias Hass Synchronisation Hutch From here the Reference Signal will be distributed Injector Laser Seed Laser Pump Probe Laser Bunch Arrival Time Monitors Laser to RF Conversion

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 16 Fundamental Concepts of Timing Systems Concept 4: Phase Synchronous References 1.M. Bousonville – For Concept 1 to 3 it is sufficient to measure only the delay changes and keep the delays stable by a control loop  |φ 1 - φ 2 | ≈ constant, but the difference is not know 3.In concept 4 the phases should be equalized, therefore not only the delay change, but also the absolute delay have to be measured and the phases adjusted  φ 1 ≈ φ 2 4.This is necessary for starting processes synchronously 5.Systems with this functionality a) White Rabbit → PH-ESE Electronics Seminars 14 May 2013 b) Universal Picosecond Timing System → will be discussed in detail

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 17 Fundamental Concepts of Timing Systems Comparison ConceptApproachReferenceApplications 1. Classic |φ 1 - φ 2 | ≈ constant RFRF Distribution 2. Low Losses |φ 1 - φ 2 | ≈ constant RFRF Distribution 3. LB Sync |φ 1 - φ 2 | ≈ constant Optical pulse train Bunch Arrival Time Measurements Laser-to-laser Synchronisation Laser-to-RF conversion 4. Phase Sync. φ 1 ≈ φ 2 Absolute time Starting processes synchronously RF Distribution

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 18 Universal Picosecond Timing System for FAIR

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 19 Overview Introduction –Motivation –Design Goal –Reference Time System Design –Basic Principle –Optical Network –Delay Measurement Unit –Reference Generator Performance Prospects Innovations Summary

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page m Motivation Cavity synchronisation  signal generation (DDS) synchronisation Therefore necessary: –Distribution of phase synchronous reference signals Problems: –Different distances  different time delays –Time delays ≠ constant CC Ref reference generator central clock signal generatorcavity f, f,  Ref Introduction

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 21 Design Goal central clock transmission unit reference generator 1 reference generator 2 Crucial: Accuracy between the reference phases Accuracy requirement: 1° at 5.4 MHz tolerance 2.5σ ΔμΔμ φ Ref φ Sys φ Optimisation Parameters: Δμ↓ and σ↓ Phase synchronisation Introduction

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 22 Reference Time Reference Signal 1 Reference Signal 2 Introduction

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 23 Reference Signal 1 T Ref,1 Command data acceptance windows T Ref,2 Reference Signal 2 Starting Points for Command Execution Introduction Starting Points

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 24 Basic Principle transmission unit reference generator delay measurement unit transmission medium signal generator cavity φ Sys φ Sys +  φ(τ) φ Ref τ Assembly of one system branch Any delay variation can be compensated  absolute delay drift irrelevant System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 25 Star-shaped distribution transmission unit delay measurement unit τnτn reference generatortransmissionsignal generatorcavity φ Ref φ Sys +  φ(τ 1 ) φ Sys One instead of N transmission units One instead of N measurement units  no different time drifts  systematic error irrelevant  much less effort reference generatortransmissionsignal generatorcavity φ Ref φ Sys +  φ(τ 2 ) reference generatortransmissionsignal generatorcavity φ Ref φ Sys +  φ(τ N ) System Design Basic Principle

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 26 central clock transmission of system clocks delay measurement generation of reference signals signal generator Subtasks and Interfaces asynchronoussynchronous System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 27 Way of Proceeding the Development 1.Identification and investigation of the most important system parameters -Noise ↓ -Crosstalk ↓  Measurement error ↓ -Unwanted reflections ↓ -Velocity of signal delay change ↓ 2.System design -Choice of technologies -Development of an measurement method -System modelling for theoretical calculation and optimization of the system parameters -Planning of the prototype (80k€ total budget  cost pressure) 3.Realisation of the prototype 4.Verification of the theoretical calculations in practice  Jitter ↓  Synchronisation error ↓ System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 28 Optical Network Configuration of one transmission branch Tx 1 Tx 2 multi- plexer λ1λ1 λ2λ2 λ 1, λ 2 FBG demulti- plexer Rx 1 Rx 2 λ1λ1 λ2λ2 Tx λMλM λMλM Rx λ 1, λ 2, λ M λMλM λ 1, λ 2 Add/Drop receiver unit transmission unit measurement unit transmission fibre circulator IN OUT ADD I1 I2 Sys. Clock 1 Sys. Clock 2 System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 29 → very good channel separation > 100 dB ele → attenuation only 4 dB opt  optical power at all receivers ≈ 0 dBm All channelsMeasurement channel (Rayleigh-Noise) Optical Network – Advantages of DWDM System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 30 Star-shaped distribution receiver unit 1 Add/Drop transmission unit optical amplifier gain = M x 3dB splitter 1 x 2 M distribution measurement unit optical switch I1 I2 receiver unit 2 receiver unit N reflector (permanent calibration) Add/Drop System Design Optical Network

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 31 Optimisation Parameter: σ = f ( σ Sys,Trans )  ok Optical Network – EDFA → Signal quality almost not effected System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 32 laser modulators switch network analyser multiplexer mirrors splitter System Design Optical Network - Prototype

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 33 Measurement Unit Delay determination via phase measurement phase measurement fMfM λ 1, λ 2 FBG Tx λMλM λMλM Rx λ 1, λ 2, λ M λMλM Add/Drop transmission fibre circulator IN OUT ADD System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 34 Not Measurable Delay Changes FBG Demulti- plexer Rx 1 Rx 2 λ1λ1 λ2λ2 λ 1, λ 2, λ M λMλM λ 1, λ 2 Add/Drop transmission fibre IN OUT ADD System Clock 1 System Clock 2 delay measurement at operation not possible I2 Error < 2.5 ps per branch  synchronisation error: Δt Sys,G < 5 ps Optimisation Parameter: Δμ = f ( Δt Sys,G )  ok System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 35 Reference Generator delay measurement DDS 1 DDS 2 phase correction signal generator Update command data I1I2I3 fibre  Sys,1  Sys,2  Sys,1 +  (  )  Sys,2 +  (  )  Ref,1  Ref,2  Kor,1  Kor,2   Kor = f (  )  Cavity reference generator central clock System Design

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 36 frequency tuning word  f Ref reset phase shifter  DDS (n) phase to amplitude converter digital to analogue converter phase accumulator + phase register z -1 + x(n)x(n) x(t) = reference signal phase tuning word  φ Kor system clock 1 08 n phase accumulator 0 8 n phase shifter  DDS,Off =  /2 0 8 n  DDS (n) 22 8 a n x(n)x(n) 0 T a t x(t)x(t) 0 System Design DDS

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 37 Reference Signal Generation via DDS principle 1.No phase adjustment limit (in contrast to other methods) 2.R esolution t S = 1.22 ps 3.Accuracy t G < 7.5 ps 4.Jitter σ RG = 7.56 ps Reference Generator System Design Martin Kumm. Integrated DDS: AD CMOS 300 MSPS Quadrature Complete DDS.

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 38 -Two Reference Points -Distance from central clock ≥ 1 km each Measurement: Δμ < 15 ps -Average interval 1 s Test of the whole System Performance

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 39 Mean time deviation Time fluctuation (Jitter) Comparison with specification Performance Accuracy of the Reference Time  one order of magnitude better than required

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page Two phase synchronous Reference Signals will be provided  universal time information -> Different RF can be derived -> Also RF ramps with adjustable offsets -> Other processes can be started synchronously Innovations

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page Optical Dense Wavelength Division Multiplex (DWDM)  separate optical measurement channel  high precision measurement  transmission of several independent System Clocks  very low transmission loss 3. Only one measurement unit with permanent calibration  systematic error irrelevant  cost-cutting 4. Direct Digital Synthesis (DDS) for generation of the Reference Time  unlimited phase shift of the Reference Signals  still the Reference Time can be adjusted in small intervals (1.22 ps) Innovations

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 42 Example: 1.Higher frequencies f Sys,1 = 1 GHz f Ref,1 = 250 MHz 2.Use of other DDS unit types 3.Temperature stabilisation DDS units  t G ↓ receiver units  Δt Sys,G ↓  σ RG ≈ 250 fs  t S = 61 fs  σ < 1 ps  Δμ << 21.2 ps Prospects Measures to Improve the Performance

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 43 1.Development of a system for distribution of a Reference Time Reference Time consists of 2 Reference Signals These Reference Signals will be provided phase synchronously at different points The signal generators of the cavities will be synchronised with these Reference Signals 2.System Optical Network Measurement Unit Reference Generators → completely prototype created 3.Accuracy of the Reference Time Mean Deviation Δμ < 21.2 ps Jitter σ = 7.57 ps → results verified at the prototype 4.Significant improvement of the performance is possible Summary  Requirements fulfilled

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 44 Prof. Dr.-Ing. Peter Meißner, Dr.-Ing. Matthias Gunkel, Dipl.-Ing. Martin Kumm and Dr. Claudius Peschke Ruth Maria Bousonville, Dipl.-Ing. Jacqueline Rausch and Dr.-Ing. Harald Klingbeil Dipl.-Ing. Enno Liess and Dr. habil. Peter Hülsmann Acknowledgements

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 45 Publications „RF Reference Signal Distribution System for FAIR”, EPAC, Genoa, Contributed talk „Universal Picosecond Timing System for the Facility for Antiproton and Ion Research”, Physical Review Special Topics - Accelerators and Beams, „Optische Übertragung phasensynchroner Taktsignale unter Verwendung des Wellenlängen-Multiplex-Verfahrens“, Dissertation, Technische Universität Darmstadt, „GSI entwickelt hochgenaues Synchronisierungssystem für Teilchen- beschleuniger“, GSI Forschungshighlights, „Hochpräzises Synchronisierungssystem für FAIR-Beschleuniger“, Wissenschaftsmagazin Target, Ausgabe Nr. 2, Juli „Velocity of Delay Changes in Fibre Optic Cables”, DIPAC, Basel, „Reference Signal Generation with Direct Digital Synthesis for FAIR”, HIAT, Venice, „Signal Delay Measurement Method for Timing Systems“, BIW, Santa Fe, USA, 2010.

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 46 Current Status of the System in FAIR

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 47 Current Status of the System in FAIR Official Name in FAIR is now BuTiS  Bunch Phase Timing System The information in the following two slides are taken from this publication.

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 48 Current Status of the System in FAIR

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 49 Starting points for command execution Interaction of White-Rabbit and BuTiS Current Status of the System in FAIR

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 50 The only Modification in the Principle delay measurement PLL phase correction signal generator Update command data I1I2I3 fibre 10 MHz 100 kHz 200 MHz 100 kHz  Kor,1  Kor,2   Kor = f (  )  Cavity reference generator central clock PLL have to lock with ° to achieve 1 ps stability Current Status of the System in FAIR

PH-ESE seminar, , Dr.-Ing. Michael Bousonville Page 51 Phone call 19th June with Bernhard Zipfel (GSI) 1.Central reference distribution and 2.6 links have been installed and commissioned beginning of 2013 => First running sub-system in FAIR 3.16 links are planned in total 4.White Rabbit is synchronized to BuTiS Current Status of the System in FAIR