Paul Scherrer Institut BPM Electronics for European XFEL and Swiss. FEL Boris Keil Paul Scherrer Institut Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Contents 1 Introduction Swiss. FEL Test Injector BPMs E-XFEL BPMs Swiss. FEL BPMs Summary & Outlook Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Introduction 2 PSI Electron BPM Systems & Design Activities Accelerator 1 st Beam # BPMs Status / Activity SLS 2000 ~140 (button, reson. stripline) Digital BPM system since 2000. 2011: Start design of new BPM electronics. SLS Linac: FEL BPM test area. Swiss. FEL Test Injector 2010 ~25 (reson. stripline, …) 19 resonant stripline BPMs in operation. Test area for cavity & button BPMs. E-XFEL 2014/15 ~410 PSI provides BPM electronics for ~290 (button, cavity) buttons & ~120 dual-resonator cavities. Swiss. FEL 2016 ~150 (cavity, stripline) Adaptation of E-XFEL cavity pickups & electronics to lower charge & shorter bunch spacing. BPM electronics PSI in–house designs, except ~30 re-entrant cavity BPM RFFE in E-XFEL (C. Simon, CEA/Saclay). Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Contents 3 Introduction Swiss. FEL Test Injector BPMs E-XFEL BPMs Swiss. FEL BPMs Summary & Outlook Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 4 Swiss. FEL Test Injector • Goal: R&D for Swiss. FEL. • Beam since 2010. • Emax~250 Me. V, 1 bunch, 10 Hz. • 10 -200 p. C. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 5 Choice of BPM & Electronics Type Goal: Want “robust” standard BPM. • Moderate resolution: ~10μm. • Large position & charge range: ± 10 mm, 10 -200 p. C. • Needed ~20 BPM working 9/2010 (too early to use E-XFEL designs …). Solution: Re-use/modify existing PSI pickup & electronics • Pickup = 500 MHz resonant stripline (used in SLS linac). • Electronics = 5 GSPS digitizer mezzanine + generic “VPC” FPGA carrier board (modified PSI muon detector digitizer). Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 6 Resonant Stripline Pickup • Already used in SLS linac & transfer lines. • Optimized for Swiss. FEL test injector: frequencies, tuners, tolerances, . . . 500 MHz decaying sine signals Antenna Tuner Boris Keil, PSI Four λ/4 resonators || beam Screen Monitor Block DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 7 Resonant Stripline BPM System VME Crate with 4 BPM electronics (see FEL 2010, WEPB 15). • RFFE filters, stretches & amplifies 500 MHz ringing signal from pickup. • Digitizer: Direct sampling with 5 GSPS, no mixer. • FPGA on VME carrier: Amplitude & position calculation. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 8 Resonant Stripline BPM: RFFE Raw 500 MHz Ringing filter output: Pulse resonant stripline stretching improves resolution signal. (reduces digitizer jitter impact). Pulse Stretching by Ringing Filter Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 9 Resonant Stripline BPM: Electronics Modules • PSI in-house design, incl. 5 GSPS analog waveform sampling chip (originally designed for low-cost sampling of some 1000 photomultiplier signals at Mu. Gamma experiment). RF Front-End Ringing Filters Input Stages Output Stages 500 MHz Ringing Filter Response General-Purpose “VPC” FPGA VME Board (Design 2004) 5 GSample/s Digitizer Mezzanine Mezz. Slot Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 10 Analog Waveform Sampling Chip Low-cost 5 GSample/s Domino Ring Sampler (DRS) Chip - Principle Domino Wave PSI design (S. Ritt): ~15 CHF per 8 -channel chip at 10 k quantities Write Switch To external ADC Sample&Hol d Capacitor Read Switch [S. Ritt, "Design and Performance of the 5 GHz Waveform Digitizing Chip DRS 3", IEEE Nucl. Sc. Symp. Conf. , Honolulu, 26. Oct - 3. Nov. 2007] Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 11 Pickup Voltage Signal Waveforms Low-passed pickup signal (scope measurement). 5 ns FPGA calculates envelopes of RFFE signals. Beam position calculated from integrals. RFFE output, digitized by BPM electronics (5 Gsps), after gain/offset/jitter correction & FIR filtering in FPGA. Time 40 ns ADC Digits 40 ns 200 Boris Keil, PSI 400 Sample No. DITANET BPM Workshop 200 400 Sample No. Jan. 17, 2012
![Swiss. FEL Test Injector BPMs 12 Position Resolution BPM 2 [mm] • 7 um](https://present5.com/presentation/2120866c27bbec577005a248f1df5c21/image-13.jpg "Swiss. FEL Test Injector BPMs 12 Position Resolution BPM 2 [mm] • 7 um")
Swiss. FEL Test Injector BPMs 12 Position Resolution BPM 2 [mm] • 7 um RMS noise from 5 -500 p. C (dominated by DRS chip sampling jitter). • 30 um RMS noise at 1 p. C (thermal noise ~1/Q). • For 16. 2 mm geometry factor (45° strip angles), >20 mm pp-range. Correlation of 3 adjacent BPMs: 1800 position measurements (over 3 minutes). (BPM 1+BPM 3)/2 [mm] Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 13 Charge Resolution Charge at BPM Difference to adjacent BPM 20 f. C Difference to BPM 2 [p. C] Charge at BPM 1 [p. C] • Correlation of adjacent BPMs: ~4 f. C RMS noise @ 400 f. C bunch charge Data from Swiss. FEL test injector. BPM charge resolution better than WCM, Faraday cup & ICT … Bunch No. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Contents 14 Introduction Swiss. FEL Test Injector BPMs E-XFEL BPMs Swiss. FEL BPMs Summary & Outlook Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 15 E-XFEL • L ~ 3400 m. 17. 5 Ge. V. SASE <0. 1 nm. • Trains of ~2800 bunches @ 10 Hz. • ~222 ns min. bunch spacing. • 20 -1000 p. C / bunch. Originally 100 -1000 p. C. . . Main linac tunnel Gun m Boris Keil, PSI Beam distribution, max. 5 undulators m m m DITANET BPM Workshop m m User experiments m m Jan. 17, 2012
E-XFEL BPMs 16 E-XFEL BPMs: Collaboration Team and Deliverables FPGA Firmware/ Software RF Front-End Electronics Cold Button 56 DESY** PSI PSI Re-Entrant Cavity 26 CEA/Saclay** PSI Warm Button * 237 DESY** PSI PSI Transfer Line Cavity 24 DESY** PSI PSI Undulator Cavity 98 DESY** PSI PSI * Different types / pipe apertures needed (beam dump: 100 mm, transfer lines: 40. 5 mm, …) ** See talks from D. Lipka & C. Simon -- cold -- ---- warm --- BPM Type Pickup / Count Mechanics ADC, Digital Back-End Electronics Preliminary • Modular electronics, common “generic” digital back-end. • Pickup-specific RF front-ends. • Common hardware & firmware: Less work & costs. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 17 BPM Performance Requirements • Table from BPM CDR 2010. Preliminary (length, quantities, …). • Most values from beam dynamics work package (Decking et al. ). [1] Warm button: Flanged version & welded version (where flanged is too long) Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 18 Undulator Cavity BPM: Design • Based on 4. 8 GHz SPring 8/SCSS design. • Adapted to E-XFEL (3. 3 GHz, …). Same BPM electronics for 10 mm and 40. 5 mm aperture: <fcut-off Frequency (both resonators) 3. 3 GHz Loaded Q (both resonators, desired mode) ~70 Q (uncoupled modes) typ. 200 -300 Sensitivity 2. 9 V/(n. C*mm) Thermal noise (lossless cables & electronics, …) 55 nm @ 20 p. C Angle signal (90° to position signal) 1 mm * dx/dz Reference cavity beam half-cut Boris Keil, PSI Position cavity 100 mm D. Lipka/DESY DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 19 Undulator Cavity BPMs (Cont’d) Flash beam test: Position resonator spectrum vs. cavity position (motorized 2 D mover) 10 ns Power [d. Bm] 3. 3 GHz Dipole mode Flash beam test: 3. 3 GHz Position resonator signal (~2. 7 V/(n. C*mm)) x [m m ] Monopole mode (suppressed by coupler) Boris Keil, PSI DITANET BPM Workshop 1 2 3 4 5 6 7 8 f [GHz] D. Lipka/DESY Jan. 17, 2012
E-XFEL BPMs 20 Transfer Line Cavity BPM • 3. 3 GHz, 40. 5 mm aperture. • Used for: Transverse intra-train feedback, energy measurements, launch jitter control & correction (energy, BAM, linac entry, …), optics measurements, … 255 mm Similar to undulator type, slightly less resolution (~20%). Main differences: ~16 x more angle signal (→ align 16 x better), cavity spacing ( → crosstalk). Frequency (both resonators) 3. 3 GHz Loaded Q (both resonators, desired mode) ~70 Q (uncoupled modes) typ. 200 -300 Sensitivity 2. 5 V/(n. C*mm) Thermal noise (lossless cables & electronics, …) 65 nm @ 20 p. C Angle signal (90° to position signal. Cause: Misalignment) ~16 mm * dx/dz Boris Keil, PSI DITANET BPM Workshop D. Lipka DESY Jan. 17, 2012
E-XFEL BPMs 21 Cold & Warm Button BPM • Cold Button : Aperture 78 mm. • Warm Button: Aperture 40. 5 mm (transfer line), 100 mm (beam dump). • Version with and without flange (space requirements …). • Warm Button: ~3 x better position resolution @ low charge than cold button Prototype installed at FLASH, test with beam (aperture: 2 x, button size: 1. 5 x). (April/May 2011) D. Lipka et al. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 22 Modular BPM Unit (“MBU”) • 19’’ housing, power supply, fans, … • Contains 4 button RF front-ends (RFFEs), or 2 cavity RFFEs, or combination. • Common digital-back-end FPGA board (GPAC = Generic PSI ADC carrier) + two ADC mezzanines. MBU for two undulator BPMs Boris Keil, PSI Control, timing & feedback interfaces: Multi-gigabit fiber optic links. Multiprotocol & baud rate support (PCI-e, Ethernet, …) DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 23 MBU BPM data processing & storage, RFFE tuning, calibration, … Control system interface: VME, VXS, or front-panel fiber optic links (Ethernet, …). Power. PC in FPGA can run Linux/EPICS. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 24 Button BPM RFFE • Input filter (bandpass, 1. 3 GHz notch, …). • Variable gain stage (>40 d. B), calibration pulser. • Peak detector with hold capacitor. Discharge: Automatic (resistor) or triggered (GPAC FPGA). • Status: PCB being soldered, lab & beam test Q 1 -2/2012. Modular design: Fast design iterations (if needed). Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 25 Button BPM RFFE (Cont’d): Input filter • Dispersive input filter stretches button pickup pulse. • Eases signal handling (linearity/saturation, …). • Bandwidth >1 GHz: More energy, better low-charge resolution. Notch @ 1. 3 GHz (avoids noise from high -power RF …) Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 26 Button BPM RFFE : PCB Floor Plan Differential coax outputs to ADCs: Low noise. Active temperature stabilization Monitoring of power supply voltage & current Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 27 Power Supply Regulators Control I/O Circuits Calibration Pulser Detector, Discharger and Buffer Add-On Modules Hot-Swap Controller +5 V and +12 V VME P 2 RF Amplifier Chain and Step Attenuator RF Shield removed Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 28 Hot-Swap Controller 12 V Chirp Filter Module Biasing of Calibration Switches Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 29 Button BPM Algorithm Concept Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 30 Undulator Cavity BPM RFFE IQ demodulation of 3. 3 GHz cavity RFFE signal to baseband 4 gain ranges (>20 d. B) 3 LOs. Phase & frequency programmable. ADC clock synthesis Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 31 Undulator Cavity BPM RFFE • 2 nd version (2011): Active temperature stabilization, solid shielding, ADC clock synthesis, more gain ranges, … • Beam tests: 1 -2μm RMS noise @ FLASH without adjusting gain, delays, LO, … (1 shift, lack of time …) → expect < 1μm if adjusted. • Lab & beam test with properly adjusted/calibrated RFFE ongoing. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 32 Undulator & Button BPM ADC Mezzanines Cavity BPMs: 6 -channel, 16 -bit, 160 MSamples/s. Button BPMs: 8 -channel, 12 -bit, 500 MSamples/s. Both types: Differential coax inputs, 150 ps step clock phase adjust per ADC. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 33 Cavity BPM Electronics: ADC Mezzanine Board Six 16 -bit 160 Msps ADCs 500 pol. High Speed Connector (Carrier Board FPGA Interface) Differential Inputs Low Jitter Clock Distribution (80 fs) On-Board Gain and Offset Calibration Control Unit Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 34 Digital Back-End (GPAC) FPGA Board: Hardware • Mid 2010: First prototype delivered to PSI. • Only faults found & fixed: Few capacitor values (time constant for power-up) changed, EEPROM replaced (was too small). • Working fine, extensive tests done. Now: Focus on firmware/software & long-term beam tests. Boris Keil, PSI DITANET BPM Workshop X-ray quality control (RAMs, connector) Jan. 17, 2012
E-XFEL BPMs 35 GPAC: FPGA Firmware/Software Cavity BPM: Storage of ADC waveform in RAM working (2 GByte/s, complete bunch train) Position calculation in FPGA Control system interface for long-term beam tests (PSI, FLASH) implemented. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 36 E-XFEL Cavity BPM: Test @ Swiss. FEL Test Injector 2 D Mover Three E-XFEL undulator cavity PU & one beamline cavity PU E-XFEL cavity BPM electronics for 2 BPMs (works in MBU and standard VME crates) • Status: Waiting for beam for multi-BPM noise correlation (after shutdown). Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 37 MBU For Two Cavity BPMs: Beam Test @ SLS Linac Reference cavity signal splitter Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
E-XFEL BPMs 38 E-XFEL Cavity BPM: Latest Beam Test @ SLS Linac Signal of one cavity BPM pickup split to two electronics: ~300 nm noise ~500 nm drift. Drift will be reduced (phase feedback, I/Q imbalance calibration, . . . ) Parasitic test during SLS operation: SLS top -up injection caused spikes (arrival time switched by N*2 ns) Time scale: 2 h Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Contents 39 Introduction Swiss. FEL Test Injector BPMs E-XFEL BPMs Swiss. FEL BPMs Summary & Outlook Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL BPMs 40 Swiss. FEL • L~700 m. 5. 8 Ge. V. SASE, λmin=0. 1 nm. • Trains of 2 bunches (1 per undulator). • ~28 ns bunch spacing, 100 Hz. • 10 -200 p. C. S-band injector X-band RF cav. 0. 7 -7 nm, seeding option SASE 0. 1 -0. 7 nm Low-emittance laser RF gun Boris Keil, PSI C-band linac Kicker (t~30 ns) DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL BPMs 41 Quantities Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL BPMs 42 Differences to E-XFEL • Official charge range: 10 -200 p. C. But: Trend to shorter bunches & lower charge. Be prepared for ~2 p. C. . . • Linac: 2 bunches, 28 ns spacing, 100 Hz. • Officially: 1 Bunch in undulators (distribution kicker). BPM System • Injector: Keep resonant striplines (+ E-XFEL button elec. ), or use 2 -resonator 3. 3 GHz cavity (budget-dependent. . . ). • Undulators + Linac: Baseline = 2 -resonator cavity BPM. • Based on E-XFEL systems, but adapted to low charge, shorter bunch spacing, different timing/control system, . . . Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL BPMs 43 Swiss. FEL Undulator Pickup: Position Cavity • Option 1: Use optimized 3. 3 GHz version. RF design finished (Fabio Marcellini, HFSS). Now production in PSI workshop, then beam test. • Option 2: Use higher frequency (e. g. 4. 8 GHz). Being investigated. Electrical Parameters Stainless Steel Copper coated Geometrical Parameters [mm] Frequency [GHz] 3. 301 3. 305 R 37 L 15 QL 69 79 G 7 S 11 0. 1369 0. 0190 T 7 Rs /x [Ω/m] 44. 9 51. 4 wg. W 34 0. 65 wg H 4 Qe 160 162 wg L 25 Sensitivity [V/n. C/mm] 9. 35 9. 30 a 6. 5 b 25 R/Q/x [Ω/m] Boris Keil, PSI ~3 x higher than E-XFEL: 340 nm RMS @ 10 p. C with 20 d. B margin for cable/noise. Penalty: More angle sensitivity. . . DITANET BPM Workshop Fabio Marcellini Jan. 17, 2012
![Swiss. FEL BPMs 44 Swiss. FEL Undulator Pickup: Reference Cavity Geometrical Parameters [mm] Electrical](https://present5.com/presentation/2120866c27bbec577005a248f1df5c21/image-45.jpg "Swiss. FEL BPMs 44 Swiss. FEL Undulator Pickup: Reference Cavity Geometrical Parameters [mm] Electrical")
Swiss. FEL BPMs 44 Swiss. FEL Undulator Pickup: Reference Cavity Geometrical Parameters [mm] Electrical Parameters Copper R 23. 5 3. 307 L 13 Frequency [GHz] G 3 QL 80 T 3 S 11 0. 9283 D 4. 5 β 26. 9 Rs [Ω] 1195 Additional goal: Cost / tolerance optimization R/Q [Ω] 14. 9 Qe 83 Sensitivity [V/n. C] 62. 2 Uncritical Fabio Marcellini Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Contents 45 Introduction Swiss. FEL Test Injector BPMs E-XFEL BPMs Swiss. FEL BPMs Summary & Outlook Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Summary & Outlook 46 • Swiss. FEL Test Injector BPMs: Goal achieved – using robust “proven” (non-final) electronics allows to work on E-XFEL & final Swiss. FEL designs without being bothered by operators • E-XFEL button electronics: Test start Q 1/2012. Could also be used for Swiss. FEL injector resonant striplines (to be tested). • E-XFEL 3. 3 GHz cavity BPMs: Lab & single-pickup beam tests promising. Next steps: Multi-pickup correlation, long-term test with beam (Swiss. FEL test injector, then FLASH), userfriendly operation & automation. • Final Swiss. FEL cavity BPMs: Sub-µm resolution <10 p. C feasible keeping 3. 3 GHz E-XFEL frequency. Higher frequency, impact & removal of angle signal (digitally/mechanically) to be investigated. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
PSI Team & Credits 47 E-XFEL/Swiss. FEL BPM Electronics: Raphael Baldinger (Electronics Tech. ) Robin Ditter (Electronics Tech. ) Waldemar Koprek (Firmware/Software Engineer) Reinhold Kramert (Electronics Eng. , MBU) Goran Marinkovic (Firmware/Software Engineer) Markus Roggli (Electronics Eng. , ADCs) Markus Stadler (RF Engineer, Cavity Electronics) Daniel Treyer (RF Engineer, Button & Stripline Electronics) Swiss. FEL BPM Pickups: Fabio Marcellini (RF Engineer, INFN / PSI guest scientist, Cavity BPMs) Martin Rohrer (Mech. Engineer) Micha Dehler (RF Engineer, Resonant Stripline) Alessandro Citterio (RF Group, Resonant Stripline) And: Thanks also to Volker Schlott & SER, support from other PSI/GFA groups, DESY E-XFEL diagnostics team (E-XFEL pickups) & Claire Simon/CEA (re-entrant E-XFEL BPM pickup & RFFE). Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Paul Scherrer Institut Thank you for your attention! Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Supplementary Slides … Boris Keil, PSI DITANET BPM Workshop 49 Jan. 17, 2012
Introduction 50 RF BPMs: Pickup Types Button (E -XFEL) Matched stripline (FLASH) Resonant stripline (Swiss. FEL test injector) Beam Position = k * (Vx 1 -Vx 2)/(Vx 1+Vx 2). Factor k (~10 mm) determined by geometry. Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Introduction 51 RF BPMs: Pickup Types (Cont’d) Single-resonator cavity (E-XFEL, cold linac, “reentrant”) Dual-resonator cavity (EXFEL undulators) Reference cavity: signal ~ bunch charge Position cavity: signal ~ position * charge 100 mm D. Lipka/DESY f. Pos = 1. 7 GHz f. Ref = 1. 2 GHz f. Pos = f. Re f = 3. 3 GHz Lower electronics drift Beam Position = k * (VPos_Mode / VRef_Mode). Factor k: Not fixed, variable via attenuator: Zoom! Boris Keil, PSI DITANET BPM Workshop Visible: Vacuum, couplers High resolution: Mode-selective couplers suppress undesired other modes Jan. 17, 2012
Introduction 52 RF BPMs: Pickup Types (Cont’d) Low cost: Standard BPM Pickup Best resolution, lowest drift: Undulator BPM Button Matched Stripline Resonant Stripline Cavity Monopole Mode Suppression Modal (hybrid) / electronics Modal (coupler), frequency, phase (sync. det. ) Typical RMS Noise, 10 p. C, *20 mm pipe* ~200μm <80μm <4μm ~1μm 300… 800 MHz 500 -1500 MHz 3 -6 GHz Spectrum Typical Electronics Frequency “Typical” noise: Examples & estimates (scaling, …) based on existing systems, not theoretical limit … Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Introduction 53 RF BPMs: Pickup Types (Cont’d) • Buttons: Moderate resolution @ low charge. O. K. with long bunch trains (E-XFEL): Averaging. • Striplines (matched + resonant): Better low-charge SNR that buttons (resonant: >10 x). O. K. for low-charge single-bunch injector/linac/transfer lines. • Single-resonator cavity + normal couplers: Commonmode suppression limits performance. • Dual-resonator cavity + mode-suppressing couplers: Optimal performance (common mode suppression, drift, …), highest SNR. Undulator BPM for LCLS, SACLA, E-XFEL, Swiss. FEL, … Boris Keil, PSI DITANET BPM Workshop Jan. 17, 2012
Swiss. FEL Test Injector BPMs 54 DRS Chip: Features and Characteristics • 8 channels, 1024 samples/channel. • Max. sample rate 5 GSa/s, on-chip PLL. • Usable input bandwidth > 500 MHz. • Random jitter (2 - 4 ps rms) limits SNR. • Deterministic jitter (50 ps rms) removed by calibration and real-time spline interpolation via FPGA FW/SW. Deterministic Jitter [ps] Systematic & Random Sampling Jitter DRS 3 DRS Chip MUX Analog Front-End Boris Keil, PSI Sampling Core Trigger ADC 16 bit 33 MHz FPGA DITANET BPM Workshop Jan. 17, 2012
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