1. 2 nd ILC Accelerator Workshop (Personal Impressions of a Beam Instrumentalist) Manfred Wendt Sept. 7, 2005 Seminar on Beam Instrumentation Techniques and Technology http://alcpg2005.colorado.edu/

2. Organization and Statistics Working Fields: Detector Physics Accelerator (2 nd ILC Accelerator Workshop) Education and Outreach Participants (1 st week): ≈ 650 total (≈ 80 Fermilab) ≈ 250 accelerator experts ≈ 15…20 typical GG/WG attendance

3. Accelerator Working Groups GG1 Parameters GG2 Instrumentation GG3 Operations & Reliability GG4 Cost & Engineering GG5 Conventional Facilities GG6 Physics Options WG1 LET Beam Dyn.WG2 Main LinacWG3a SourcesWG3b DRWG4 BDSWG5 CavityWG6 Communication Global Group Sub-System WG

4. 1 st Week Plenary Presentations (Mo, Fr) Parallel Session Talks (Tu, We, Th) 2 nd Week WG Discussions (Mo…Th) Plenary Presentations (Fr) Special Events 7x Lunch-Time Seminars Evening Events, Discussions, Dinner,…

5. The GDE Plan and Schedule 2005 2006 2007 2008 2009 2010 Global Design EffortProject Baseline configuration Reference Design ILC R&D Program Technical Design Bids to Host; Site Selection; International Mgmt LHC Physics

6. ILC Goals and Parameters E cm adjustable from 200 – 500 GeV Luminosity  ∫Ldt = 500 fb -1 in 4 years Ability to scan between 200 and 500 GeV Energy stability and precision below 0.1% Electron polarization of at least 80% The machine must be upgradeable to 1 TeV

7. Configuration Parameter Space

8. 48 BCD Questions (Himel’s List) 2. Beam and luminosity parameters? 3. SCC “starting” gradient and upgrade path? 4. 1 or 2 IR’s? 5. 1 or 2 tunnels, deep or shallow? 6. DR size and shape? 7. e + source: conv., undulator, compton?... 29. How many diagnostic sections in the linac? 33. MPS design? 35. Use structure (HOM) BPM’s? 43. Re-entrant or cavity BPM’s for the main linac?

9. Global Group 2: Instrumentation & Controls Conveners: Marc Ross (SLAC), Hans Braun (CERN), Junji Urakawa (KEK) Presentations: S-Band Cavity BPM for ILC Linac, Zenghai Li Cold Linac BPM’s, Manfred Wendt Cold BPM Options, Olivier Napoly Cold Re-entrant BPM, Claire Simon ILC Cavity BPM’s, Steve Smith ILC Laserwires, Grahame Blair Survey and Alignment of ILC, Armin Reichold Beam Based Feedback Systems, Phil Burrows High Availability Electronics & Standards for ILC, Ray Larsen Stabilization of the Final Focus, David Urner

10. Beam Position Monitors Cold Linac BPM’s: 2 x 400 dedicated re-entrant cavity or CM-free cavity BPM’s 2 x 10000 HOM (structure) monitors for beam displacement (???)

11. Simple “Pill-Box” Cavity BPM Problems: TM 010 monopole common mode (CM) Cross-talk (xy-axes, polarization) Transient response (single-bunch measurements) Wake-potential (heat-load, BBU) Cryogenic and cleanroom requirements

12. CM-free Cavity BPM’s KEK ATF nanoBPM collaboration: BINP cavity BPM C-Band (6426 MHz) 20 mm aperture Selective dipole- mode waveguide couplers 3 BPM’s in a LLBL hexapod spaceframe (6 degrees of freedom for alignment) Dual-downconversion electronics (476 & 25 MHz) 14-bit, 100 MSPS digitizer

13. BPM ASSEMBLY BPM struts

15. Beam Parameters Q bunch ≈ 1.5 nC σ x ≈ 80 µm σ y ≈ 8 µm σ z ≈ 8 mm (!) ΔE/E ≈ 5 E-4 Jitter: - σ x ≈ 20 µm - σ y ≈ 3.5 µm - σ’ x ≈ 1000 µrad - σ’ y ≈ 2 µrad Signal Processing Digital Downconversion: –Multiply digital waveform by complex “local oscillator” e i  t –Low-pass filter (currently 2.5 MHz B/W) Sample complex amplitude of position cavity at “peak” Divide by complex amplitude from reference cavity Scale/rotate by calibration constants Refine calibration with linear least- squares fit to other BPM measurements, e.g. y 2 pred = f(y 1,y 3,x 2 ) –Removes beam jitter, rotations, cal. errors. –Monopole modes appear as offset in (I,Q) space (as do mixer offsets, rf leakage).

16. 10 minute run 800 samples σ ≈ 24 nm Move BPM in 1 µm steps

17. Cavity BPM Shapes

18. KEK Cavity BPM Very compact design to save space –Waveguide has fold, asymmetry Differs from BINP design –BINP BPM has long waveguide taper to coax adapter –KEK coax adapter is very close to cavity

19. X1 X2 Y1 Y2 KEK group sees ~ 70 nm resolution Also X-Y coupling Monopole mode leakage

20. Re-entrant Cavity BPM Coaxial cavity BPM Evanescent fields of the TE 11 dipole mode Very low Q ≈ 4 Cryogenic and cleanroom approved

21. Improved re-entrant BPM design: Better to be cleaned (12 holes) More reliable feedthrough construction Reduced damping –Q dipole ≈ 52 (f dipole = 1.72 GHz) –Q mono ≈ 24 (f mono = 1.25 GHz) Expected single-bunch resolution ~ 1 µm

22. Q43: Re-entrant or Cavity BPM? Answer: Not yet decided, R&D required! Re-entrant BPM meets cryogenic and cleanroom requirements, but has limited resolution*. CM-free cavity BPM meets resolution requirements*, but has to show cryogenic and cleanroom compatibility. * The required single-bunch resolution was set by GG2 to σ/3 ≈ 0.5 µm for diagnostic purposes, WG1 (LET) assumes 1…10 µm BPM resolution.

23. Accelerating Cavity HOM Couplers as BPM (HOM-BPM) Naturally narrow band cavity : Q L ≈ 104,  ≈ 1 µs single bunch, but not bunch to bunch BPM Relative position resolution ~ 4 µm (cf. M. Ross and J. Frisch).

24. 1 2 3 4 5 polarization directions x y Centering accuracy < 40 µm, using a single mode (2 polarisations) Angular scan resolution and accuracy < 50 µrad

25. High Availability Electronics ATCA Telecom System: A=0.99999 2 Control & 12 Applications slots Up to 200 W/module at 45ºC ambient, 2.8KW Shelf Redundant speed controlled DC fans Mezzanine Card Option 3x7inch Hot Swappable Up to 8/Mbrd

26. Data Acquisition & Controls Total Instru mentTypelocation Temporal ResolutionResolutionprimary data primary data ratestatus data rate 400BPM button, stripline, cavityInjectors & BC150…300 nssigma/3hor., vert., int. nb x 3 wd / 200 ms 1 status wd / 200 ms 800BPM cavity, re-entrant (cold)Main Linacs150...300 ns sigma/3 (0.5 um) hor., vert., int., tilt, yaw nb x 5 wd / 200 ms 1 status wd / 200 ms 500BPMcavity, striplineBDS150…300 ns sigma/3… sigma/10 hor., vert., int., tilt, yaw nb x 5 wd / 200 ms 1 status wd / 200 ms 36BPMcavity BDS spectrometer150…300 ns100 nm hor., vert., int., tilt, yaw nb x 5 wd / 200 ms 1 status wd / 200 ms 2BPMstriplineIP feedback150…300 ns1 umhor., vert. nb x 2 wd / 200 ms 1 status wd / 200 ms 800BPMbuttonDamping Rings100 kHz / 2 kHz0.5…1 umhor., vert., int. ca. 3 x wd / 500 us 1 status wd / 200 ms 6BPMcavity, striplineDR feedback3…20 ns< 0.5 umhor., vert.nb x 2 wd / trev 1 status wd / 200 ms 100BPMbutton MPS (everywhere)10 us50 umhor., vert., int. nb x 3 wd / 200 ms 1 status wd / 200 ms > 100BLM ionization chamber MPS (everywhere)beam loss1 wd / 200 ms 1 status wd / 200 ms 20000BPMHOMMain Linacs1 ms< 1 um beam displacement1 wd / 200 ms 1 status wd / 200 ms 50BCMtoroideverywhere3…20 ns0.5 %intensity nb x 1 wd / 200 ms 1 status wd / 200 ms 4BCM wall current monitorInjector & BC780 ps1 %intensity nbt x 1 wd / 200 ms 1 status wd / 200 ms 50 Beam Phasering electrode?everywhere 0.1 degree @ 1.3 GHzbunch phase nb x 1 wd / 200 ms 1 status wd / 200 ms

27. Personal Impressions Many beam instrumentation collaborations in progress: –SLAC, KEK, LLNL, LBL, …: nanoBPM’s at ATF –SLAC, DESY: HOM-BPM at TTF –CEA-Saclay, DESY: Re-entrant BPM at TTF –SLAC, DESY: LOLA long. bunch profile at TTF –SLAC, Uni London (QM): Fast IP feedback at the SLAC Linac –Uni London (RH), JAI, DESY: Laserwire trans. profile at PETRA Very good working atmosphere! Technology choice (1.3 GHz SC Cavities) accepted! SLAC seems to me very active(!), not only in the field of beam instrumentation.