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.