and Programs for ILC at KEK-ATF We are going to research and develop - - PowerPoint PPT Presentation

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Research and Development Status and Programs for ILC at KEK-ATF

Junji Urakawa (KEK) at Oxford, 10/27

We are going to research and develop on

advanced accelerator technology under International Collaboration (ATF-MoU) for ILC at KEK-ATF. I will report the highlight

• f present research programs and prospect the

future, especially the results of ATF2 project in 2008.

2

ATF Status and Prospect

Emittance status, BPM Improvement, Laser wire results, Pulsed laser wire development, ODR monitor results, Fast kicker R&D, Laser Interferometer in an Optical Cavity New device for nm beam control.

3

ATF Introduction

ATF Damping Ring

Electoron Linac BT ( Beam Transport Line ) Extraction Line

SR Monitor RF Cavity Wiggler Injection Kicker Seputum Magnets Extraction Kicker Wiggler

East Arc North Straight South Straight West Arc

Wire scanner

E=1.28GeV Ne=1x1010 e-/bunch 1 ~ 20 bunches Rep=3.125Hz X emit=2.5x10-6 Y emit=1.25x10-8 as normalized emittance

4

Multibunch emittance study

• Scrubbing of DR was started

DR pressure should be < 7 x10-7 Pa for 1% emittance ratio

for 1.0 x1010 e-, 20 bunches, (=67mA, beam scrubbing with 210mA is necessary.) 0.78Hz repetition so far, >1 x10-6 Pa - <5x x10-7 Pa

• Monitors of MB emittance

MB (or projected) Laser-wire Projected SR interference monitor, X-ray SR monitor MB (or projected) wire scanner: (EXT-line coupling problem?)

• Problem of MB emittance

Fast Ion Instability ?

Energy fluctuation ( coupled bunch longitudinal oscillation ?)

5

6

0.0 100 1.0 10-11 2.0 10-11 3.0 10-11 4.0 10-11 5.0 10-11

5 10 15 20 Vertical Emittance of Multibunch

Y_emittance(00mode, 1.6E9intensity) Y_emittance(00mode, 3.7E9intensity) Y_emittance(01mode, 6.3E9intensity)

Vertical Emittance of each bunch Bunch Number

1.6x109 3.7x109 6.3x109 GLC Design 1 10-11 2 10-11 3 10-11 4 10-11 5 10-11 5 10 15 20

MB emittance after 5.5A.hour scrubbing

Y emi(1.1e9/bunch intensity) Y emi(4.1e9/bunch intensity) Y emi(5.2e9/bunch intensity)

Y emittance of each bunch bunch number

1.1x10

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4.1x109 5.2x10

9

Fast Ion Instability: Experimental Results at ATF Required vertical emittance : 2pm rad for ILC Vacuum Pressure<10-8 Pa (0.1nTorr) in ILC

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ATF Damping Ring BPM

reference plane reference plane EBW reference plane 19.5 mm ceramics button (SUS304) flange (A3003) HIP transition top block (Ti) SMA connector pin (Kovar) brazing (Ag-Cu) brazing (Al)

Button BPM for Damping Ring

ø24mm

70mm

Button electrode assembly cross section of BPM camber

Electronics: single pass detection for 96 BPMs DC-50MHz BW, base line clip & charge ADC,

• min. resolution ~20µm

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Spectrum of DR BPM

Signal peak at ~ 1GHz

40 45 50 55 60 65 107 108 109 1010

DR BPM(MB30R) spectrum [dBµV]

Freqency [Hz]

DR button BPM beam signal spectrum

• ut from 40m RG223/u cable

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BPM electronics improvement

Electronics: 40MHz - 1GHz BW, base line clip & low noise LF amp

• min. resolution ~2µm

ch 1 ch 2 ch 3 ch 4

calibration pulse

HPF 50MHz LPF1000MHz ATT LPF135MHz

Gain change

RF amp 40 ~ 1000MHz Gain 28.5dB 25dBm output LF amp DC~ 155MHz Gain 15dB 19dBm output Microwave diode detector 600 ~ 1000MHz

RF combiner 4-way splitter

• 20dB

Improved BPM Circuit ( simplified diagram )

single bunch multibunch ch 2 ch 3 ch 4

SMA SMA SMA SMA SMA

QLA QLA QLA QLA

gain change control

flat

ch 1 ch 2 ch 3 ch 4

signal from BPM signal to charge ADC

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1 10 100 108 109 1010 1011 Estimated Resolution [µm] Bunch Intensity [electrons/bunch] Existing circuit (estimated by beam)

Improved circuit (estimated by calibration pulser)

Resolution Improvement

• Min. resolution ~ 2µm

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Vertical orbit Improvement

• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5 20 40 60 80 100

Y orbit before BPM improvement (26Nov2002)

Y C.O.D. [mm] BPM number

• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5 20 40 60 80 100

Y orbit after BPM improvement (20May2003)

Y C.O.D. [mm] BPMnumber

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Vertical dispersion Improvement

• 15.0
• 10.0
• 5.0

0.0 5.0 10.0 15.0 20 40 60 80 100

Y dispersion before BPM improvement (26Nov2002)

Y dispersion [mm] BPMnumber

• 15.0
• 10.0
• 5.0

0.0 5.0 10.0 15.0 20 40 60 80 100

Y dispersion after BPM improvement (20May2003)

Y dispersion [mm] BPMnumber

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X to Y coupling Improvement

• 200.0
• 150.0
• 100.0
• 50.0

0.0 50.0 100.0 150.0 200.0 20 40 60 80 100 dY by ZH2R 26Nov2002 dY[micron]

BPMnumber

• 200.0
• 150.0
• 100.0
• 50.0

0.0 50.0 100.0 150.0 200.0 20 40 60 80 100 dY by ZH4R 26Nov2002 dY[micron]

BPMnumber

• 200.0
• 150.0
• 100.0
• 50.0

0.0 50.0 100.0 150.0 200.0 20 40 60 80 100 dY by ZH2R 20May2003 dY[micron] BPMnumber

• 200.0
• 150.0
• 100.0
• 50.0

0.0 50.0 100.0 150.0 200.0 20 40 60 80 100 dY by ZH4R 20May2003 dY[micron] BPMnumber

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Laser wire beam size monitor in DR

14.7µm laser wire for X scan 5.7µm for Y scan (whole scan: 15min for X, 6min for Y) 300mW 532nm Solid-state Laser Fed into optical cavity

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Laser wire block diagram

• ptical cavity resonance is kept by piezo actuator

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Two important cavity parameters

• There are two important parameters

which characterize the cavity. – Finess (F): sharpness of resonance

• proportional to power gain (G)
• determined by mirror reflectivity
• measured by its transmitted light.

– Waist (w0): thinness of the beam

• measure of spatial resolution or

luminosity

• determined by cavity geometry
• measured by phase difference

between two modes (or e- beam itself)

– F.o.m: G/(w0)n (n=1~2)

• F and w contradict technically.

transmittance Observed Airy function Half of wavelength Peak width: 0.3nm Timing accuracy :1asec

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Beam profile by Laser wire

σe

2 = σmeas 2 - σlw 2

εβ = σe

2 – [η(∆p/p)]2

β:measured by Q-trim excitation

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Energy Spread

by beam size monitor at EXT dispersive point

4.5 10

• 4

5.0 10

• 4

5.5 10

• 4

6.0 10

• 4

6.5 10

• 4

7.0 10

• 4

7.5 10

• 4

8.0 10

• 4

8.5 10

• 4

2 10

9

4 10

9

6 10

9

8 10

9

1 10

10 1.2 10 10

Energy Spread (runD) Energy Spread (run E) simulation (0.4% coupling) simulation (6% coupling)

Energy Spread Bunch Intensity [electrons/bunch] 15 20 25 30 35 40 2 10

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4 10

9

6 10

9

8 10

9

1 10

10 1.2 10 10

bunch length(runD') [psec] bunch length(runE') [psec] bunch length(runF') [psec] simulation (0.4% coupling) simulation (6% coupling) simulation (3% coupling)

Bunch Length (rms) [psec] Bunch Intensity [electrons/bunch]

Bunch Length

by SR monitor with streak camera

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Emittance by Laser wire

< 0.5% y/x emittance ratio

Y emittance =4pm at small intensity

1 10-9 1.2 10-9 1.4 10-9 1.6 10-9 1.8 10-9 2 10-9 2 109 4 109 6 109 8 109 1 1010

X emittance by LW

X emittance (single bunch) emitt_x

X emittance Bunch Intensity

0.5% coupling Calculation LW X emit(single 16APR03) 2 10-12 4 10-12 6 10-12 8 10-12 1 10-11

2 109 4 109 6 109 8 109 1 1010 Y emittance by LW

Y emittance (single bunch) Y emittance (15bunch projected) emitt_y

Y emittance Bunch Intensity

0.5% coupling Calculation LW Y emit(single 16APR03) LW Y emit(15 bunch 6JUN03)

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Results with higher transverse mode

• Resolution may be

improved by ~x3 with the same w0.

How to make TE01 mode?

01

00 00

TEM01 mode was produced with efficiency of 60% by inserting phase converter.

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Laser:

Mode Lock: Passive SESAM Frequency: 357MHz Cavity length: 0.42 m Pulse width: 7.3 p sec (FWHM) Wave Length: 1064 nm Power: ~ 6W SESAM: SEmi-conductor Saturable Absorber Mirrors

Experimental results （ Pulse Laser Storage ）

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Cavity: Super Invar Cavity length: 0.42 m Mirrors: Reflectivity: 99.7%, 99.9% Curvature: 250 mm (

0 = 180

m)

• Ext. Cavity:

62φ super invar

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Finesse: R = 99.9%

Finesse = c/l

: decay time c: light verocity l: cavity length

F ~ 6300 (Preliminary) ~ 3.0 sec

PD Trans.

P.C.

PBS PBS

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Plused Laser and Electron Beam Collision to measure bunch length

Pulse Laser Wire (Storage laser pulses in optical cavity ): The systems for New X-ray source & New bunch length monitor at a storage ring

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714MHz Cavity Electron repetition rate : 357MHz Electron bunches Laser Repetition rate : 357MHz laser pulses Scattered Gamma beam Compton Scattering in every 357MHz As an X-ray source : An optical cavity stores higher peak power and gets higher flux X-ray with pulse laser than CW laser. As Beam monitor : By scanning the laser pulse’s phase in the cavity and measuring the Compton signal count rate ; an electron bunch length profile is obtained. Phase Scan

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Storage of laser pulse

Resonance condition :

Perfect resonance : L = L Not resonance : L ≠ L Imperfect Resonance : L ～ L

laser laser laser cavity cavity cavity

The relationship with laser and cavity : The enhancement factor is the function of reflectivity, l and laser pulse width.

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Count rate & Measurement

～

Laser pulse width

• Laser

beamwaist e bunch length e h-beamsize

• 2

2 2 2 2

Phase

σ = σ +σ

Vertical position

2 2 2

Laser beamwaist e v-beamwaist

• Signal flux

2

The electron bunch length is 20 ～ 40 psec (10mm) Laser pulse width ( FWHM =7 psec ; 1 mm) Laserwire beamwaist( 120um ), electron’s horizontal beamsize ( 100um ) Suppose both electron bunch and laser pulses have a Gaussian intensity distribution, the measured profile is also a Gaussian shape.

e bunch length

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OPTICAL CAVITY

• Cavity length : 714 MHz +/- 2 kHz ( from PZT dynamic range )
• Mirrors
• The radius of curvature : 250 mm
• The reflectivity : 0.997 +/- 0.001
• Beamwaist > 200 um

Cavity length is 210mm. It is easy to adjust cavity length with short cavity. For cavity’s dynamic range , long PZT is used ( 10um ). Finesse is ～ 1000 . But effective finesse is ～ 500 ,when the length of cavity is 21cm. 4 times reflections occur during each laser pulse injection. It is difficult to make thin laserwires at long cavity length.

Adjustment with PZT

714MHz corresponds 21cm.

= 250mm R = 0.997

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OPTICAL CAVITY : feedback circuit

Transmission Mode locked Laser Laser Rep.rate feedback Signal Generator Ring RF standard 10MHz

357MHz PZT voltage PI circuit DC

Shoulder feedback system ( OFF : background) By a phase detector, the signal is synchronized with Ring RF. A trombone for a signal delay

← Feedback ON/OFF

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EXPERIMENTAL SETUP : Optics

Isolator

Cavity Transmission Reflection Injection mirrors Laser head /2 /4

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Count rate

Calculated maximum count rate is ～ 2500 [Hz/mA] . Actual count rate is ～ 1500 because of imperfectly adjustment cavity length with shoulder feedback system.

=laser beamwaist

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When bunch current is increased , the Gauusian shape of photons count rate changes.

Count rate [Hz/mA] Phase [psec]

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C W L a s e r F a b r y

• P

e r

• t

C a v i t y P u l s e

• S

t a c k i n g F a b r y

• P

e r

• t

C a v i t y t = 1 / 4 f t =

For more γ generation : Storage of short pulse laser and Crossing angle less than 5 degrees to make near head-on. Large optical cavity (Super-Cavity) will be developed. Off axis parabolic mirror is necessary. Then, new cavity like below type will be developed.

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ODR Monitor

ODR Target chamber ODR Target Holder

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Experimental study on optical diffraction radiation

ODR by single edge

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OTR ETR

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How to measure beam size from ODR angular distribution. We have to use slit target and measure the interference from both edges. Slit Target

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Yx is much more sensitive to the beam size. We already measured interference of ODR from both edges and found fine interference structure due to synchrotron radiation from a near bending magnet.

R= Y

x

Y

x max x

= 2



R 1−R

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VMOS Technology by FID GmbH

Fast Kicker R&D : Present Technology on Pulse PS

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Strip line kicker modules

Fast switches dump high voltage pulses into a series of strip line structures. Electromagnetic pulse applies transverse kick to one bunch, but is absorbed in a load in each strip line module before next bunch arrives.

• switch speed, on-resistance, and stability are concerns
• adequate precision of strip line termination is challenging

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Measurement result of FPG5-3000M Rise time~3.2ns Kick angle ~85µrad (calc. 94.7µrad)

Expanded horizontal scale

20 40 60 80 100 10 12 14 16 18 20

Pulse timing v.s. kick angle(FID FPG-3000M)

KickAngle(urad) Delay(ns) Time

20 40 60 80 100 5 10 15 20 25 30

Pulse timing v.s. kick angle(FID FPG-3000M)

KickAngle(urad) Delay(ns) Time

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Principle of Laser Interferometer in an Optical Cavity for nm resolution

L=0.42m =1064nm =282THz =714MHz T=1.4ns

Short laser pulse can be generated by many longitudinal waves which are completely mode-locked. 7psec pulse width requires 200 longitudinal modes in the case

• f 714MHz repetition rate.

FSR: = c 2L T= 1 = 2L c =M× c 2L =M×

*This is frequency consideration. *Tow modulation methods for

• ptical cavity are

space of the cavity and frequency of mode-locking.

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k

= k× ∣k∣≤m,M=2m1 Et=∑

k=−m m

E

k

t=∑

k=−m m

E e

i2

k

t

¿E e

i2 t

∑

k=−m m

e

ik2 t

¿E e

i2 tsinM

t  sin t 

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Check by Mathematica in my laptop computer

Cavity Length =420mm, Center of the Cavity is z=0. Two 7psec laser pulses are moving upward and downward from high reflective Mirrors at t=0.

710.000762psec later

• 4
• 2

2 4 5000 10000 15000 20000 25000 30000 35000 40000

705.000762psec later

• 3
• 2
• 1

1 2 3 5000 10000 15000 20000 25000 30000 35000 40000

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Interference

• 0.002
• 0.001

0.001 0.002 25000 50000 75000 100000 125000 150000

• 0.002
• 0.001

0.001 0.002 25000 50000 75000 100000 125000 150000

• 0.002
• 0.001

0.001 0.002 25000 50000 75000 100000 125000 150000

• 0.002
• 0.001

0.001 0.002 25000 50000 75000 100000 125000 150000

700.0033psec later 700.003psec later 700.00076psec later 700.002psec later

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e -beam

• Pulse Laser beam

(357 MHz)

We changed the length of the optical cavity from 840mm to 420mm since we could order 741MHz mode-lock laser. Specification of the 714MHz mode- lock laser 800mW, 7psec pulse width(FWHM) 0.4psec(rms) timing jitter First step : Comfirmation of Interference Second step : Movement of the Interference by phase shift or mover Table Third step : Installation into ATF Damping ring

Plan of Test Experiment

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Future plan for reliable nano beam size monitor

• We will design the chamber which includes

vertical 42cm optical cavity and is attached with upstream cavity BPM and downstream cavity BPM. Two BPMs can measure the beam orbit within the accuracy of a few nano-meter.

• We will change the laser wavelength from

1064nm to 532nm(Green).

• This is a backup system for Shintake

monitor.

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High power pulsed laser-wire location cw laser-wire and pilsed laser location with optical cavity

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ATF Extraction line laser-wire

Vacuum vessel + lens Designed and built at Oxford Vacuum vessel installed in ATF Oct 05 Data taking planned for Dec 05

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Mission of ATF/ATF2

ATF, to establish the technologies associated with producing the electron beams with the quality required for ILC and provide such beams to ATF2 in a stable and reliable manner. ATF2, to use the beams extracted from ATF at a test final focus beam-line which is similar to what is envisaged at

• ILC. The goal is to demonstrate the beam focusing

technologies that are consistent with ILC requirements. For this purpose, ATF2 aims to focus the beam down to a few tens of nm (rms) with a beam centroid stability within a few nm for a prolonged period of time. Both the ATF and ATF2, to serve the mission of providing the young scientists and engineers with training

• pportunities of participating in R&D programs for

advanced accelerator technologies.

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0.08% Energy Spread 1.2 × 1010 Single bunch population ~8mm (26 ps) Bunch Length (1.4 ± 0.3) × 10-9 m rad Horizontal (1.5 ± 0.25) ×10-11 m rad Vertical Beam emittance 1.28 GeV ( =2500) Maximum energy

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• 1. Pol. Positron generation R&D at EXT (ended June 2005)
• 2. Laser wire R&D in Damping Ring (Kyoto University)
• 3. High quality electron beam generation by photo-cathode RF

Gun (Waseda University)

• 4. X-SR Monitor R&D (University of Tokyo)
• 5. ODR R&D (Tomusk University)
• 6. Beam Based Alignment R&D
• 7. Nano-BPM project of SLAC, LLNL and LBNL
• 8. Nano-BPM project of KEK
• 9. FONT project (UK Institutes)
• 10. Laser Wire project at EXT (UK Institutes)
• 11. Fast Kicker Development project (DESY, SLAC, LLNL)
• 12. Fast Ion Instability Research
• 13. Multi-bunch Instability Study

Present Research Programmes at ATF

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2 x 600 mm triplets of cavity BPM’s; spacing ~ 5 m.

K E K L L N L A cavity triplet is used to determine resolution

2 Cavity BPM triplets in ATF Extraction Line

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ATF Nano BPM

K E K L L N L

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Installation of the LLNL space frame support  3 BINP cavity BPM’s inside with precision movers March 2004

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C-Band Cavities

BINP Cavities (Vogel, et al.) ~ 2cm aperture Dipole-mode selective couplers

Charge Q ~ 1.5 nC Spot size: x ~ 80 µm y ~ 8 µm z ~ 8mm (! ) Energy dispersion ~ 10-3 E/E ~5 10-4 Position & angle jitter:

x 20 µm

y 3.5 µm x’ 1000 µrad ’ 2 µrad Incoming beam params:

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BPM ASSEMBLY

BPM struts

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Calibrate

• Move one BPM at a time with movers
• Extract BPM phase, scale, offset as well as beam motion by linear

regression of BPM reading against mover + all other BPM readings.

Calibration

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Short Term Resolution

• 1 minute
• 100 pulses
• s = 17 nm
• Is it real ?

Predict Y2 from other BPMs Linear least-squares fit to (x, y, x’, y’) at BPMs 1&3

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Optical Geodetic structure

• Considering two

different setups:

rigidly mounted rigidly mounted

Cartoon for Setup 1: 2-dimensional Grid of distance meters (Michelson Interferometers)

x y z

Oxford Optical Geodesy Group – Reichold/Urner

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• FONT UK:
• Queen Mary: Philip Burrows, Glen White, Glenn Christian,
• Hamid Dabiri Khah, Tony Hartin, Stephen Molloy,
• Christine Clarke, Christina Swinson
• Daresbury Lab: Alexander Kalinin, Roy Barlow, Mike Dufau
• Oxford: Colin Perry, Gerald Myatt

Beam-based Feedback Systems:

FONT3 PCB amplifier + FB Same drive power as needed for ILC

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FONT3 Installation in ATF extraction line

Adjustable-gap kicker

BPM ML11X

Feedbac k Superfast BPM processor Superfast amplifier

BPM ML12X BPM ML13X

Aim: TOTAL latency < 20 ns

• Demonstrated feedback

with delay loop

• Ultra-fast system: total

latency 23 ns

• Varied main gain, delay

loop length, delay loop gain

• system behaves as

expected

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• ATF/(ATF2): 1.3 GeV beam, 3 bunches with spacing c. 150ns
• FONT4 (2005-6):
• modified FONT3 BPM front-end signal processor
• digital FB system
• FEATHER adjustable-gap kicker
• Aiming for first demonstration of FB w. ILC-like bunches:
• latency 100ns (electronics)
• stabilisation of 3rd bunch at um level
• Possible first component tests at ATF December 2005/March 2006

FONT4: Prototype Digital Feedback System

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Feedforward to Extraction Line

nm Fast Feedback

µm Feedforward ( DR BPM -> EXT Line new strip line kicker)

Double kicker X jitter compensation

FONT project (UK Institutes)

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ATF2

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ATF2

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ATF2

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ATF2

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ATF2

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ATF2

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ATF2

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Prospect of ATF and ATF2

• ATF International R&D will generate

necessary results for ILC, especially how to control high quality beam, develop many kinds

• f advanced instrumentation, educate young

accelerator physicists and engineers.

• ILC like beam which means 20 bunches with

bunch spacing about 300nsec.

• Realization of about 35nm beam for long

period.