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

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2 nd ilc accelerator workshop personal impressions of a beam instrumentalist
2nd ILC Accelerator Workshop(Personal Impressions of a Beam Instrumentalist)

Manfred Wendt

Sept. 7, 2005

http://alcpg2005.colorado.edu/

Seminar on Beam Instrumentation Techniques and Technology

organization and statistics
Organization and Statistics

Working Fields:

  • Detector
  • Physics
  • Accelerator (2nd ILC Accelerator Workshop)
  • Education and Outreach

Participants (1st week):

  • ≈ 650 total (≈ 80 Fermilab)
  • ≈ 250 accelerator experts
  • ≈ 15…20 typical GG/WG attendance
accelerator working groups
Accelerator Working Groups

WG1 LET Beam Dyn.

WG2 Main Linac

WG3a Sources

WG3b DR

WG4 BDS

WG5 Cavity

WG6 Communication

Sub-System WG

Global Group

GG1 Parameters

GG2 Instrumentation

GG3 Operations & Reliability

GG4 Cost & Engineering

GG5 Conventional Facilities

GG6 Physics Options

slide4
1st Week
  • Plenary Presentations (Mo, Fr)
  • Parallel Session Talks (Tu, We, Th)

2nd Week

  • WG Discussions (Mo…Th)
  • Plenary Presentations (Fr)

Special Events

  • 7x Lunch-Time Seminars
  • Evening Events, Discussions, Dinner,…
slide5

The GDE Plan and Schedule

2005 2006 2007 2008 2009 2010

Global Design Effort

Project

LHC

Physics

Baseline configuration

Reference Design

Technical Design

ILC R&D Program

Bids to Host; Site Selection;

International Mgmt

ilc goals and parameters
ILC Goals and Parameters
  • Ecm 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
48 bcd questions himel s list
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?

global group 2 instrumentation controls
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
beam position monitors
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 (???)
simple pill box cavity bpm
Simple “Pill-Box” Cavity BPM

Problems:

  • TM010 monopole common mode (CM)
  • Cross-talk (xy-axes, polarization)
  • Transient response (single-bunch measurements)
  • Wake-potential (heat-load, BBU)
  • Cryogenic and cleanroom requirements
cm free cavity bpm s
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
slide13

BPM ASSEMBLY

BPM struts

slide15
Beam Parameters

Qbunch≈ 1.5 nC

σx≈ 80 µm

σy≈ 8 µm

σz≈ 8 mm (!)

ΔE/E ≈ 5 E-4

Jitter:

- σx≈ 20 µm

- σy≈ 3.5 µm

- σ’x≈ 1000 µrad

- σ’y≈ 2 µrad

Signal Processing

  • Digital Downconversion:
    • Multiply digital waveform by complex “local oscillator” eiwt
    • 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. y2pred = f(y1,y3,x2)
    • Removes beam jitter, rotations, cal. errors.
    • Monopole modes appear as offset in (I,Q) space (as do mixer offsets, rf leakage).
slide16
10 minute run
  • 800 samples
  • σ≈ 24 nm

Move BPM in 1 µm steps

kek cavity bpm
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
slide19
KEK group sees ~ 70 nm resolution
  • Also X-Y coupling
  • Monopole mode leakage

X2

Y1

Y2

X1

re entrant cavity bpm
Re-entrant Cavity BPM
  • Coaxial cavity BPM
  • Evanescent fields of the TE11 dipole mode
  • Very low Q ≈ 4
  • Cryogenic and cleanroom approved
slide21
Improved re-entrant BPM design:
  • Better to be cleaned (12 holes)
  • More reliable feedthrough construction
  • Reduced damping
    • Qdipole≈ 52 (fdipole = 1.72 GHz)
    • Qmono≈ 24 (fmono = 1.25 GHz)
  • Expected single-bunch resolution ~ 1 µm
q43 re entrant or cavity bpm
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…10µm BPM resolution.

accelerating cavity hom couplers as bpm hom bpm
Accelerating Cavity HOM Couplers as BPM (HOM-BPM)
  • Naturally narrow band cavity : QL ≈ 104 , ≈ 1 µs
  • single bunch,
  • but not bunch to bunch BPM
  • Relative position resolution ~ 4 µm (cf. M. Ross and J. Frisch).
slide24

y

5

x

4

2

1

polarization directions

3

Centering accuracy < 40 µm, using a single mode (2 polarisations)

Angular scan resolution

and accuracy < 50 µrad

high availability electronics
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

personal impressions
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.