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Overview of Electron Beam Diagnostics at FLASH: General Characteristics and Monitoring Systems

Explore the beam diagnostics overview and status at FLASH, covering charge, position, size, and loss monitors. Learn about the characteristics of FLASH1 and FLASH2, including their diagnostics systems and monitoring technologies.

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Overview of Electron Beam Diagnostics at FLASH: General Characteristics and Monitoring Systems

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  1. Overview and Status of the Standard Electron Beam Diagnostics at FLASH N. Baboi, DESYfor the Diagnostics Team

  2. Contents • Overview of standard beam diagnostics in FLASH1 and FLASH2 • General characteristics • Beam monitors • Charge Monitors • Position Monitors • Size Monitors • Loss Monitors • Not all monitor types covered by this talk

  3. Overview of Electron Beam Diagnostics in FLASH

  4. General Characteristics • General • Deliver bunch by bunch measurements, with few exceptions • FLASH1 • Most designed for TTF2, for charges of 1nC and higher • Electronics: VME-based, ADCs with 1MHz • FLASH2 • Most designed for the E-XFEL • Make use of synergies given by the similar time line • Some have been designed specially for FLASH(2) or have a temporary solution • Generally based on MTCA-technology • 9 MTCA crates for diagnostics installed at FLASH2 • Designed for lower charge J. Feldhaus, D. Nölle, EPAC2004, p. 262 N. Baboi, IBIC’14, THIXB1

  5. Charge Monitors: Toroids Charge Monitors / Toroids FLASH1 FLASH2 Temporary solution Low-gain front-end channel CAT cables (E-XFEL type under tests • All signals go to VME and uTCA-system • 3GUN and 10DBC2 have new front-end (amplifier & filter, like in FLASH2) W + Front-end W + W RTM SIS8900 Adapter RTM + W AMC SIS8300 ADC peak M. Werner, IBIC’14, WEPF02) AMP-200 ADC base VME(Fl1) uTCA(Fl1&2)

  6. Charge Monitors: Toroids (2) Resolution of charge monitors along FLASH(1) (~ 0.4 nC) oFLASH-type (VME) oFLASH2-type (MTCA) old amplifier OFLASH2-type with new amplifier ► ►Dark current monitor

  7. Toroid Protection System (TPS) • Temporary solution using 3 TPS modules designed for FLASH TPS 1 TPS 0 Soft X-ray Undulators RF Stations Photon Diagnostics sFLASH Accelerating Structures FLASH1 THz FLASH2 RF Gun Bunch Compressors Lasers 5 MeV 150 MeV 450 MeV 1250 MeV Beam Dump FEL Experiments TPS 2 (not yet commissioned) A. Hamdi, DIPAC 2007, p. 349

  8. Charge Monitors: Dark Current Monitor 7DBC2, 32m Dark current Bunch

  9. Screens at FLASH1 • Designed by INFN • Some camera-PCs have to be reset/restarted from time to time • Recently had to readjust 3 stations in DBC2 • Difficult due to missing fine adjustment • 2 are adjusted only for a magnification of 1 A. Cianchi, EPAC2004, p. 2619 • Emittance tool 23.09.2014, 13:42

  10. Screens at FLASH2 • Scintillator based (LYSO:Ce), spatial suppression of COTR • Optics: • Look under 45 deg • Uses “Scheimpflug´s” principle to extend depth of field • 10 µm resolution required • single bunch, streaked • Demonstrated at FLASH1 C. Wiebers, IBIC2013, WEPF03 DotGrid Target(spot Ø .50mm) 200µm thick LYSO Screen (ON-Axis) 2 half 200µm thick LYSO Screens (OFF-Axis) Optics Axis BEAM

  11. Screens at FLASH1 (2) • Fully commissioned FLASH1 1FL2SEED4 1FL2SEED5 FLASH2 1FL2SEED6 1FL2SEED7

  12. Wire Scanners: Zeuthen Type • One horizontal and one vertical fork, each with 3 wires • Used also for cross-calibration of BPMs • Tool for profile scans and emittance P. Castro, DIPAC 2005, p. 205

  13. Wire Scanners: MDI/CERN Type • One fork placed at 45deg with horizontal, vertical and diagonal wire • Several WS use one detector • Also possible to read signals from BLMs, with some change in the beam profile • Some have some readout/timing problems, now under work • Jddd panels to be updated M. Werner, DIPAC 2001, p. 139

  14. BPMs in FLASH1 • Button BPMs, stripline BPMs, cold cavity BPMs, button BPMs inside undulators ~0.35 nC

  15. BPMs in FLASH2: Cavity BPMs • Cavities • Dipole + reference resonator • 3.3 GHz, low Q (about 70) • 17 installed between undulators – 10 mm pipe • No individual tuning • Readout (PSI) • MBU (Modular BPM Unit) with 2 RFFE for 2 cavity BPMs • Up to 4 MBUs connected to 1 DAMC2 interface board • Timing: decoding timing protocol via fiber in MBU • Resolution requirement • 2 mm rms for 0.1-1 nC and within ± 0.5 mm(1 mm at XFEL, but longer cables at FLASH2) M. Stadler, IBIC’14, WEPD12 B. Keil, IBIC’14, WEPD11

  16. BPMs in FLASH2: Cavity BPMs: Resolution • BPMs in FLASH2 • Difference between expected and measured position with Gaussian fit • Test BPMs in FLASH1 • 0.5 mm rms for 0.24 nC bunch charge and 0.5 mm bunch offset Resolution of various FLASH1-BPMs (designed for 1 nC) D. Lipka, IBIC’14, TUPF07 preliminary ~0.35 nC

  17. BPMs in FLASH2: Cavity BPMs: Charge • Charge resolution for 100 pC bunch charge < 0.2 pCrms D. Lipka, IBIC’14, TUPF07

  18. BPMs in FLASH2: Button and Stripline BPMs • Low Charge BPMs (LCBPM) electronics • Name chosen in contrast to system designed for FLASH for charges of 1nC and higher • Designed for FLASH2 (and to be installed in all FLASH) Delay ~100ns S. Vilcins, IBIC’14, TUPF11 Broadband RF Combiner Button or Strip-line BPM RF cable 3/8“ Length < 80m Typical Signals from BUTTON/strip-line BPM B. Lorbeer, IBIC’14, TUPF08F. Schmidt-Föhre, IPAC’14, THPME117 Signal of horizontal plane, delayline: ~100ns

  19. BPMs in FLASH2: Button and StriplineBPMs: LCBPM MicroTCAcrate RF Front-End Rear Transition Module (RTM) 180mmx162mm Compatible with the MTCA.4 for physics standard Front Side 5 BPMs/crate G=38dB Att.>60dB Peak Detector Back Side RTM Analog Output Signals X-Channel 100ns Y-Channel • Crate used for the tests includes: • management carrierhub (MCH) • harddisk (HD), processor (CPU) • DigitizerSIS8300 • timing module x2timer

  20. BPMs in FLASH2: Button &Stripline BPMs: Operation Requirements (from XFEL requirements) Server Panel for Firmware Adjustment BPM Expert Panel RMS at q=36 pC, 200 pulses (incl. beam jitter) sy = 22 mm sy = 39 mm Strip-Line BPM Button BPM

  21. HOM-based Position Monitors • Monitor dipole, beam position correlated, signals excited in the accelerating cavities • Amplitude shows the beam alignment in the cavities, which influences the (transverse) beam quality • Available in ACC1 (3 cavities), ACC39 and ACC2-5 • Display only signal envelope

  22. Beam Loss Monitors in FLASH1 Cannot distinguish between losses from FLASH1 and FLASH2 pulses

  23. Beam Loss Monitor Scintillator PMT & HV Beam Loss Monitors in FLASH2 • Detector • Scintillator or fused silica (rod or fiber) • PMT: HV voltage (~500 V) generated by Cockcroft-Walton multiplier on board mounted at PMT • Scintillators and mechanics built by IHEP, Protvino (60 for FLASH2) • Electronics MTCA-based with low latency interface with MPS • Alarms algorithms • Single bunch • Multi-bunch • Integration • OR of comparator and FPGA alarms Readout Electronics Alarm (to MPS) Power control A. Kaukher, BIW 2012, p. 35 e,γ,n0

  24. Beam Loss Monitors in FLASH2: Status • Calibrated single and multi-bunch alarm • Integration alarms to be calibrated

  25. Dump Loss Monitors in FLASH1 & FLASH2: BLMs and Ionization Chambers • BLMs based on quarz-fiber + Ionization Chambers (air filled cables) along last 2m of beam line • VME/uTCA electronics FLASH1 beam N. Baboi, BIW 2010, p. 420

  26. Dump Loss Monitors: Beam Halo Monitors (FLASH1 & FLASH2) • Installed behind dump vacuum window • 8 sensors: 4 Diamond + 4 Sapphire • VME-based in FLASH1 • uTCA-based in FLASH2 • Basically same electronics and firmware as FLASH2 BLMs • Under commissioning FLASH1 A. Ignatenko, IPAC 2012, p. 816

  27. Acknowledgement • Many people contributed to the work and this talk • R. Neumann, D. Lipka, N. Wentowski, Z. Pisarov, M. Werner, J. Lund-Nielsen, B. Lorbeer, A. Kaukher, T. Wamsat, A. Ignatenko, F. Schmidt-Föhre, K. Honkavaara, H. Tiessen, B. Michalek, R. Zahn, B. Keil, D. Nölle, O. Hensler, G. Marinkovic, K. Knaack, J. Schwarz, J. Liebing, H. Sokolinski, G. Kube, C. Wiebers, M. Felber, R. Zahn, S. Vilcins, J. Kruse, D. Renner, M. Felber, S. Schreiber, M. Holz, M. Pelzer, A. Ziegler, M. Hoeptner, H. Sokolinski, M. Stadler, M. Wendt, I. Krouptchenkovand many others Thank you !

  28. Other Electron Beam Monitors in FLASH2 • Loss monitors • Cherenkov fibers along undulators (not for XFEL) • Beam Compression Monitors • Beam Arrival Monitors • Coherent Transition Radiation monitors C. Behrens, IPAC’10, p.912 A. Angelowski, IBIC’14, MOPD25 S. Wesch, BIW 2012, THAP01

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