2 nd ilc accelerator workshop (personal impressions of a beam instrumentalist) manfred wendt sept....
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22ndnd ILC Accelerator Workshop ILC Accelerator Workshop(Personal Impressions of a Beam Instrumentalist)(Personal Impressions of a Beam Instrumentalist)
Manfred WendtSept. 7, 2005
Seminar on Beam Instrumentation Techniques and Technology
http://alcpg2005.colorado.edu/
Organization and StatisticsOrganization 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 GroupsAccelerator Working Groups
GG1 Parameters
GG2 Instrumentation
GG3 Operations & Reliability
GG4 Cost & Engineering
GG5 Conventional Facilities
GG6 Physics Options
WG
1 LET
Beam
D
yn.
WG
2 Main Linac
WG
3a Sources
WG
3b DR
WG
4 BD
S
WG
5 Cavity
WG
6 Com
municationGlobal Group
Sub-System WG
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,…
The GDE Plan and Schedule The GDE Plan and Schedule 2005 2006 2007 2008 2009 2010
Global Design Effort Project
Baseline configuration
Reference Design
ILC R&D Program
Technical Design
Bids to Host; Site Selection;
International Mgmt
LHCPhysics
ILC Goals and ParametersILC 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
Configuration Parameter SpaceConfiguration Parameter Space
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:Global Group 2:Instrumentation & ControlsInstrumentation & 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 MonitorsBeam 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 BPMSimple “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’sCM-free Cavity BPM’sKEK ATF nanoBPMcollaboration:• 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
BPM ASSEMBLY
BPM struts
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” eit
– 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. y2
pred = 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).
• 10 minute run• 800 samples• σ ≈ 24 nm
Move BPM in 1 µm steps
KEK BPM
BINP BPM
ATF2 BPM
Cavity BPM Shapes
KEK Cavity BPMKEK 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
X1
X2
Y1Y2• KEK group sees ~ 70 nm resolution
• Also X-Y coupling• Monopole mode leakage
Re-entrant Cavity BPMRe-entrant Cavity BPM• Coaxial cavity BPM• Evanescent fields of
the TE11 dipole mode• Very low Q ≈ 4• Cryogenic and
cleanroom approved
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…10 µm BPM
resolution.
Accelerating Cavity HOM Couplers Accelerating Cavity HOM Couplers as BPM (HOM-BPM)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).
12
34
5
polarization directions
x
y
Centering accuracy < 40 µm, using a single mode (2 polarisations)
Angular scan resolutionand accuracy < 50 µrad
High Availability ElectronicsHigh Availability ElectronicsATCA Telecom System: A=0.99999ATCA 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
Fan Rear Exhaust Area
Shelf Manager Card Connection
Fabric Cabling Area
Fabric Interface Card Slots
Power Converters
Dual Network Switch Module Locations
Dual Star Fabric Connectors
48V DC Power Plugs
Redundant Shelf Manager Cards
Fan area
Mezzanine Card Option3x7inch Hot SwappableUp to 8/Mbrd
Data Acquisition & ControlsData Acquisition & ControlsTotal
Instrument Type location
Temporal Resolution Resolution primary data
primary data rate status data rate
400 BPMbutton, stripline, cavity Injectors & BC 150…300 ns sigma/3 hor., vert., int.
nb x 3 wd / 200 ms
1 status wd / 200 ms
800 BPMcavity, re-entrant (cold) Main Linacs 150...300 ns
sigma/3 (0.5 um)
hor., vert., int., tilt, yaw
nb x 5 wd / 200 ms
1 status wd / 200 ms
500 BPM cavity, stripline BDS 150…300 nssigma/3… sigma/10
hor., vert., int., tilt, yaw
nb x 5 wd / 200 ms
1 status wd / 200 ms
36 BPM cavityBDS spectrometer 150…300 ns 100 nm
hor., vert., int., tilt, yaw
nb x 5 wd / 200 ms
1 status wd / 200 ms
2 BPM stripline IP feedback 150…300 ns 1 um hor., vert.nb x 2 wd / 200 ms
1 status wd / 200 ms
800 BPM button Damping Rings 100 kHz / 2 kHz 0.5…1 um hor., vert., int.ca. 3 x wd / 500 us
1 status wd / 200 ms
6 BPM cavity, stripline DR feedback 3…20 ns < 0.5 um hor., vert. nb x 2 wd / trev1 status wd / 200 ms
100 BPM buttonMPS (everywhere) 10 us 50 um hor., vert., int.
nb x 3 wd / 200 ms
1 status wd / 200 ms
> 100 BLMionization chamber
MPS (everywhere) beam loss 1 wd / 200 ms
1 status wd / 200 ms
20000 BPM HOM Main Linacs 1 ms < 1 umbeam displacement 1 wd / 200 ms
1 status wd / 200 ms
50 BCM toroid everywhere 3…20 ns 0.5 % intensitynb x 1 wd / 200 ms
1 status wd / 200 ms
4 BCMwall current monitor Injector & BC 780 ps 1 % intensity
nbt x 1 wd / 200 ms
1 status wd / 200 ms
50Beam Phase ring electrode? everywhere
0.1 degree @ 1.3 GHz bunch phase
nb x 1 wd / 200 ms
1 status wd / 200 ms
Personal ImpressionsPersonal 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.