1

ATF Status LCPAC 2005.02.25 K.KUBO

IntroductionEmittance

Single bunch and multi-bunch in DRExtracted beam

Wiggler studyOther experiment, Instrumentation development, etc.

Polarized positron productionOptical Diffraction RadiationLaser WireCavity BPM Intra train Feedback, , , , ,

2

ATF: Accelerator Test FacilityPrimarily for LC study

Electron Linac

Extraction Line

Linac

Damping Ring

E=1.3GeVNe=1x1010 e-/bunch1 ~ 20 bunches/train1 ~ 3 trains/ring

3

ATF operation International collaboration

• ATF operates for 21 weeks/year; 110 hours/week

• Participation from outside Japan greatly increased 2004/05 (25 visiting researchers including 10 students/post-docs)– Will use 30% of beam time this year

• Host duties shared between KEK/SLAC• Operation fully supported by KEK

M.Ross

4

Single bunch Transverse Emittance

y/x emittance ratio <0.5% (y ~ 1.5E-8 m) is constantly achieved in single bunch operation.

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 2 109 4 109 6 109 8 109 1 1010

Horizontal Emittancex emittance (run B)x emittance (run D)simulation (0.4% coupling)

x e

mit

tan

ce [

10-9

]

bunch intensity [electrons/bunch]

GLC Design

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 2 109 4 109 6 109 8 109 1 1010

Vertical Emittancey emittance (run B)y emittance (run D)simulation (0.4% coupling)

y e

mit

tan

ce [

10-1

2]

bunch intensity [electrons/bunch]

GLC Design

in the damping ring measured by Laser wire

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Multibunch Vertical Emittance in the damping ring measured by Laser wire

Laser wire measures projected profileof many turns.Oscillation is appeared to be beam size blow up.

0.0 100

1.0 10-11

2.0 10-11

3.0 10-11

4.0 10-11

5.0 10-11

0 5 10 15 20

Vertical Emittance of Multibunch

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

Ver

tica

l E

mit

tan

ce o

f ea

ch b

un

ch

Bunch Number

1.6x109

3.7x109

6.3x109

GLC Design

Emittance Versus Bunch Number

0.00E+00

1.00E-08

2.00E-08

3.00E-08

4.00E-08

5.00E-08

6.00E-08

0 5 10 15 20 25

BunchN

orm

aliz

ed Y

Em

itta

nce

6.00E+09

3.70E+09

1.60E+09

Schematic of the Fast-Beam Ion Instability

Fast beam ion instability simulation

(by T.Raubenheimer)

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Effect of ‘scrubbing’

Fast ion instability has been observed as multibunch emittance blow up measured by Laser Wire at high intensity.

‘Scrubbing’ (improving vacuum level) was expected to suppress the instability.But, it has not been fully confirmed yet.

Due to a vacuum accident in January 2005, it will be delayed.

No big blow up of the tail bunches after ‘scrubbing’.But emittance tuning was not sufficiently good.

Vertical beamsize vs. bunch number

After ‘scrubbing’ 5.5 A hour

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Extracted beam emittance is larger than in the damping ring.Unknown higher order fields in the kickers and the septum magnetsare suspected.(Kicker will be replaced in this summer.)

Vertical emittance of extracted beam

0

5 10-12

1 10-11

1.5 10-11

2 10-11

2.5 10-11

3 10-11

0 2 109 4 109 6 109 8 109 1 1010

Extracted, wire scannerIn DR, laser wireIn DR, laser wire

y (m

)

N

Vertical emittance vs. bunch population.

Emittance in DR was measured by Laser wire,in extraction line by wire scanners.

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Wiggler study

Correction of end poles.

Started in Oct. 2004.Basic performance with wigglers

damping timesemittances

Effects of non-linear field of wigglers.dynamic aperture

Total Length 2.0 mOne period 0.4 mFull gap 20 mmBpeak 1.62 T (1000A)Beff 1.40 T (1000 A)Current/pole 20 KA (20 turns)Number of poles 9(full) + 2(half)

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Wiggler off calc. Wiggler on calc.

x (ms) 19.3 + - 0.63 17.5 15.7 + - 0.38 14.2

y (ms) 28.8 + - 1.5 28.5 25.4 + - 0.67 21.1

z (ms) 21.4 + - 3.9 20.5 14.2 + - 2.4 14.0

Damping time with/without wigglers (preliminary).

Horizontal beam size vs. time.(Extracted beam.)

without wigglerwith wiggler

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Horizontal and Vertical emittance w/wo wigglers.

Horizontal emittance with wigglers was smaller than that without wigglers, as expected.

Small vertical emittance was achieved both with and without wigglers.

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Preliminary test of effect of wigglers to dynamic aperture. Non-linear field of wigglers is expected to reduce dynamic aperture.

Beam life time w/wo wigglers vs. horizontal tune.

without wiggler

with wiggler

x

B

eam

life

tim

e (S

)

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Other Beam studies• Compton-based Polarized Positron production • ODR (Optical Diffraction Radiation for beam monitors) • FEATHER(KEK)/FONT(QMUL) (intra-pulse orbit feedbac

k)• RF-gun (high quality multibunch beam generation)• SR monitors ( interference, streak, longitudinal osc.) • XSR (beam size monitor using X-ray synchrotron radiation)• Laser Wire in Damping Ring (CW and Pulse stacking) • Laser Wire in extraction line (will start in 2005) • Cavity BPM (SLAC+ and KEK+) • ring-BPM (SLAC +) • Beam dynamics in DR (LBL, KEK, , , , ,)

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Polarized gamma-ray production byPolarized Laser light – electron collision

Polarized positron production experiment

T.Omori

ATF extraction line

14T.Omori

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Measured Asymmetry and polarization of e+

A= +0.71± 0.23 %

A= -1.1± 0.23 %

Magnet polarity

Laser polarity

preliminary

Pol(e)=99± 22%

Laser polarityMagnet polarity

statistical error only

T.Omori

[Turned out to be e-]

proportional to Number of transmitted gamma-rays

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ODR (Optical Diffraction Radiation) study at ATF extraction line

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Measurements of the ODR projected vertical polarization component using a photomultiplier (PMT) and comparison with the theory

mrad14.0

mrad9.5

y

x

Detector acceptance

y

-15 -10 -5 0 5 10 15

Inte

nsi

ty n

orm

aliz

ed b

y m

uxi

mu

m.

0.0

0.2

0.4

0.6

0.8

1.0

ODR

Intensity and angular distribution ofODR was consistent with calculations.

ODR by P.KarataevBeam size, y (m)

0 10 20 30

min

imu

m /

max

imu

m

0.00

0.04

0.08

0.12

(minimum/maximum)

y

Beam size is evaluated from bottom/top ratio.

calculation

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Comparison of the beam sizes measured with ODR and wire scanners

Wire beam size (m)

0 10 20 30

OD

R b

eam

siz

e (

m)

0

10

20

30

Correlation between the the ODR and the beam size measured with 10m tungsten wire installed in the target chamber at the same position as the target. The black line represents a 45 degree line.

ODR by P.Karataev

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y (mm)-6 -3 0 3 6

x (m

m)

-6

-3

0

3

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A new technique for beam size measurement using ODR from a ‘dis-phased’ target.

A new model for calculating diffraction radiation (DR) characteristics from a charged particle moving through a slit between two flat plates inclined with respect to each other around the axis perpendicular to the slit has been developed. A one-dimensional lens can bring two DR cones together producing an interference pattern, which is very sensitive to transversal electron beam size. The sensitivity in this case depends on the DR observation wavelength and the angle between the planes. The analysis of the model shows that

this technique allows to measure sub-micron beam sizes.

2

e _

x s

y s

4

a ina out

b out

ODR geometry

ODR interference pattern that could be observed with a

CCD

ODR by P.Karataev

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714MHz (21cm) Optical resonator cavity(Cavity length should be controlled ~1nm for resonance)

Electron beam: bunch spacing 1/357 MHz (2.8 ns)

Laser Pulse. =1064 nmPulse length = 2 mm

Repetition 357MHz(Spacing should be controlled ~ 1 m for pulse stacking)

Scattered Photon(Detected)

Compton Scattering, 357MHz

•　 High intensity hard X-ray source•　 Beam monitor

Application

Penetrated light: Monitored for cavity length feedback

Pulse Stacking Laser Wire Test in ATF DRPulse Laser Wire (K.Takezawa)

Mirrors: optical resonatorto enhance photon intensity

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Damping Ring

12.7 m

4.8 m

electronLaser wire

Collimetor: 0.2mrad -> photon energy 12 ~ 14.5 MeV

Detector

Backgroundsubtraction

Pulse Laser Wire (K.Takezawa)

Enhancement by factor 50 was confirmed. = CW laser by factor 10000

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Electron bunch length was measured.

Laser Timing (ps)0 2008040 120 140

Count (Hz/mA)

800

1000

600

400

200

Bunch length

Count rate vs. Timing

RF system of Damping Ring(Define electron bunch timing.)

(Laser pulse length ~ 2 mm << electron bunch length)

Pulse Laser Wire (K.Takezawa)

Proof of principle of enhancement of pulse laser by resonatorwas done. For practical use, higher intensity is necessary. Optical cavity with amplification factor 500, waist size 50 m is designed. (present cavity: factor ~100, waist size 250 m )

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UK: Pulsed Laser-wire at the ATF Extraction Line

• University of Oxford:N. Delerue, B. Foster, D. Howell, A.ReicholdI. Ross (CCLRC)

• Royal Holloway University London:I. Agapov, G. Blair, G. Boorman, J.Carter, C. Driouichi, M.Price

• University College London:S. Boogert, S. Malton

• KEK:H. Hayano, P. Karataev, K. Kubo, J.Urakawa

• SLAC:J. Frisch, M. Ross

Start in March and full system commissioning by December

• Goal: Measure the electron beam profile with a resolution of ~1 m.

G. Blair

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2 cavity BPM triplets in the ATF Extraction line

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

KEK

US

A cavity triplet is used to determine resolution

M.Ross

Cavity BPM Study

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Cavity BPM nm resolution study (US)

LLNL Design frameShould be very rigid;relative position jitter due to vibration < nm.

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Cavity BPM resolution tests:Residual of center BPM wrt predicted position from 1st and 3rd.Rms <20 nm for 600 pulsesPlot scale is +80 / -60 nm

(results from 12.04; first commissioning run)

M.Ross

BPM resolution = rms*sqrt(2/3) 17 nm

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Long term stability (for 1 hour) - average residual of 40 sets of pulse sequences (4e3 pulses total); rms offset drift = 44 nm.

M.Ross

200

nm

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Y.Honda

Totally different idea of support and position control.

(KEK)

29UK LCABD Collaboration LCPAC2005, KEK 25/02/05

• FONT: Queen Mary: Philip Burrows, Glen White, Glenn Christian,

Hamid Dabiri Khah, Tony Hartin, Stephen Molloy, Christine Clarke

Daresbury Lab: Alexander Kalinin, Roy Barlow, Mike Dufau

Oxford: Colin Perry, Gerald Myatt

SLAC: Joe Frisch, Tom Markiewicz, Marc Ross, Chris Adolphsen, Keith Jobe, Doug McCormick, Janice Nelson, Tonee Smith,

Steve Smith, Mark Woodley

• FEATHER: KEK: Toshiaki Tauchi, Hitoshi Hayano

Tokyo Met. University: Takayuki Sumiyoshi, Hiroyuki Fujimoto

• Simulations: Nick Walker (DESY), Daniel Schulte (CERN)

Fast FB (Intra-pulse orbit feedback)International Collaboration

30UK LCABD Collaboration LCPAC2005, KEK 25/02/05

FONT3 at ATF (started Nov 2003)Original aim: • Demonstrate micron-level stabilisation of 1.3 GeV ATF beam with

latency c. 20 ns for warm machine.• Worth completing, though low latency critical only for CLIC

Adjustable-gap kicker

BPM ML11X

Feedback

SuperfastBPM processor

Superfastamplifier

BPM ML12X

BPM ML13X

Correct orbit of tail bunches using information of head bunches

beam

ATF extraction line

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FONT3 BPM processor (single-bunch data from December 2004 beam tests)

Latency~ 4 nsBPM

UK LCABD Collaboration LCPAC2005, KEK 25/02/05

32UK LCABD Collaboration LCPAC2005, KEK 25/02/05

Possible Future Beam Feedback Tests

Short-term: expect to finish FONT3 in 2005

Long-term:

demonstrate robust intra-train FB system for ILC, based on digital signal processing, and ideally test with beam:

requires long bunchtrain with 337 ns bunch spacing

2005-6: FONT4: 3 bunches x 150 ns at ATF would allow first tests:

stabilise last bunch at 100 nm level (?) as part of Nano project

also feed-forward studies ring -> extraction line?

2007: FONT5: 20 bunches x 337ns at ATF/ATF2 would allow FB algorithm development

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ATF is intended to:1. generate the low emittance beam needed for the linear colli

der and

2. test the required precision control and monitoring technology

• Low emittance beam that needed in LC was demonstrated– Typical damped beam y: 4 pm-rad, y: 0.1 nm-rad at

1.3 GeV (typical beam size = 5 µm)– (emittances required in the TESLA design: y: 2 pm-rad,

y: 0.2 nm-rad at 5 GeV)– Multibunch operation and extracted beam have problem

s.

Summary-1

M.Ross, K.Kubo

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Summary-2 : Role of ATF in the next stage of the ILC project

• Beam dynamics study– emittance tuning and coupling control 1 pm-rad – performance with wiggler– fast ion instability

• Extraction kicker RD – aimed at the damping ring ‘footprint’ decision – Snowmass 08.05

• Extracted beam– precision instrumentation

• cavity BPM’s, laser-based profile monitors– feedback / stabilization

• fast ‘within the train’ feedback• laser-interferometric geodesic structure

• Small, stable ATF beam is a unique resource

M.Ross

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Summary-3 : ILC Injector study list (from Int’l workshop 11.04):

– DR footprint; pre-damping ring– fast rise / fall time extraction– emittance tuning– collective effects e cloud / fast beam ion– wiggler optimization and dynamic aperture

• ATF can address most of these and Beam Delivery list also – with extracted beam

Injector study plans Next speaker(s)

M.Ross

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ATF Plans for 2005-2006• MB emittance study Y emittance will be confirmed by Laser Wire after scrubbing.• Wiggler study Effect of non-linear field to dynamic aperture.• High quality beam extraction multi-pole component of kicker and septum are under study.• nm resolution BPM test & demonstration Development of new precise mover & new cavity-BPM electronics.

• Fast feedback test & demonstration Basic test of feedforward and feedback are under way. Fast feedback test by 3 train extraction (ILC-like bunch spacing) will be done.

• Fast Kicker for ILC damping ring Fast pulse power supply and strip line kicker system will be tested.

• Instrumentation developments LW, XSR monitor, ODR monitor, MB-BPM, (SB, MB) longitudinal feedback, etc.

• Preparation of ‘ATF-2’