special lecture- atf the unique test facility for ilc with a low emittance beam
DESCRIPTION
Special Lecture- ATF The unique test facility for ILC with a low emittance beam. 1. History and Machine introduction 2. Machine performance 3. R&D Programs and ATF2 4. Highlight Studies in Extraction Line. Junji Urakawa, KEK ILC School at KEK 2006.5.27. ATF Collaboration History. - PowerPoint PPT PresentationTRANSCRIPT
Special Lecture- ATF
The unique test facility for ILC with a low emittance beam.
Junji Urakawa, KEKILC School at KEK
2006.5.27
1. History and Machine introduction2. Machine performance3. R&D Programs and ATF24. Highlight Studies in Extraction Line
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ATF Collaboration History
• ATF Construction and R&D’s have been started with SLAC from 1993.
• From 1997 International collaboration was started for the R&D’s with Damping Ring. Many oversea’s institutes were involved.
• ATF MoU was established on 1st Aug. 2005. New organized ATF international collaboration has be
en started. (20 Institutes or more were signed.) 1st ICB meeting in Snowmass, 1st TB meeting at KEK on Dec..2nd TB meeting will be scheduled in May after ILC schoo
l.• From 2008, ATF2 : the final focus test beam line, will
be operated.
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1. Usually schedule of ATF machine operation is divided to two blocks of operating time per year with about four months summer long shutdown. One block is from mid. of Oct. to Dec., and the other is from mid. of Jan. to mid. of June. Since there are many collaborators, we proposed two meetings of TB per year in Dec. and May for review and recommendation of the research programs at ATF.
2. Requests to new proposal : Purpose, Research method, Period of the research, Manpower, Budget plan etc. should be reviewed for the approval. See Template for the new proposal (see http://atf.kek.jp/).
3. Member of ATF operation group : Shift leader is responsible for the safety and should be KEK staff. Since ATF operation group is responsible for beam tuning, making a good beam and required beam by R&D group, ATF operation group can involve many physicists and engineers from oversea’s countries and, young scientists and engineers can learn how to make the good beam.
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Assignment of the ATF Beam Time
TB:ApprovedStudies
~2/3
SP:ApprovedStudies
Beam Tuning
Maintenance
Typical ~22 weeks/yearAbout 20 % of total will be used for the maintenance and the beam tuning.It is estimated by current results.
Guideline for approved studied by SP.1. Short term study2. No conflict with approved studies by TB and ICB.3. Test study for new proposal4. SP can accept until two shifts/weekbut it depends on the situation of studies.
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Schedule of ATF operation, TB meeting and Long shutdown
Feb Apr Jun Aug Oct Dec Feb Apr Jun
JFY NEXT JFY
ATF Summer shutdown 22 beam weeks / 32 weeks Summer
Beam (KEK power contract) Shutdown
ScheduleUpgrade / MaintenanceInstallation
May Dec. MayTB meeting TB meeting TB meeting
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Mission of ATF
1. Establish the technologies associated with producing the electron beams of the quality required for ILC.
2. Provide such beams to ATF2 in a stable and reliable manner.
3. Serve the mission of providing the young scientists and engineers with training opportunities of participating in R&D programs for advanced accelerator technologies.
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Introduction ATFAccelerator Test Facility
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Machine performanceLook at experimental measurement results.
Multi-bunch electron beam generation
Gun cavity
High quality Multi-bunch beam is generated.1 ~ 20 bunches / pulse, 2.8ns spacing~ 2 x 1010 electrons / bunch
-0.5
0.0
0.5
1.0
1.5
-1 10-8 0 1 10-8 2 10-8 3 10-8 4 10-8 5 10-8 6 10-8 7 10-8
RF gun beam at 80MeV
Wal
l cu
rren
t m
on
ito
r at
80M
eV
Time [sec]
-0.5
0.0
0.5
1.0
1.5
-1 10-8 0 1 10-8 2 10-8 3 10-8 4 10-8 5 10-8 6 10-8 7 10-8
RF gun beam at 80MeV
Wal
l cu
rren
t m
on
ito
r at
80M
eV
Time [sec]
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Laser wire scanner in DR for X & Y scan, for single/multi-bunch
TEM00 wireTEM00 wire
TEM01 wireTEM01 wire
Two optical cavity chamberTwo optical cavity chamberFor X-wire and Y-wireFor X-wire and Y-wire
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Possibility of 1pm-rad y
Kubo's simulation:BPM offset error should be < 0.1
mm. (“BBA”)Then, εy ~ 2 pm will be achieved.
Magnet re-alignment, < 30 μm.Then, εy ~ 1 pm will be achieved.
Optics model should be good.Quad strength error should be < 0.5(?) %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
tanc
e [1
0-1
2]
bunch intensity [electrons/bunch]
GLC Design
Measured in DR
Single bunch
Beam dynamics study
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High power pulsed laser-wire location
cw laser-wire and pulsed laser locationwith optical cavity
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Maximum energy 1.28 GeV (γ=2500)
Beam emittance
Vertical (1.5 ± 0.25) 10-11 m rad
Horizontal (1.4 ± 0.3) 10-9 m rad
Bunch Length ~9mm (30 ps)
Single bunch population 2.0 1010
Energy Spread 0.08%
Typical Beam Parameters in Damping Ring
Beam Scrubbing of DR, example
60~70mA (20bunch, 3train);1.3~1.5x10-6 pa --> 1.0~1.1x10-6 pa
- 210mA possible
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R&D Programs and ATF2• 1. kicker study for extraction of ILC-like bunch spacing.1. kicker study for extraction of ILC-like bunch spacing. Multi-pole component of kicker and septum is under study.• 2. Fast rise/fall strip-line kicker study for ILC Damping Ring.kicker study for ILC Damping Ring. <3ns rise/fall is under study.• 3. High resolution Ring-BPM for more small vertical emittance.3. High resolution Ring-BPM for more small vertical emittance. application of digital signal process is under study.• 4. Coherent Synchrotron Radiation(CSR) study. development of CSR detection is underway.• 5. Cavity BPMs.5. Cavity BPMs. nm resolution BPMs, PAL-BPM at ATF2, IP-BPM at ATF2.• 6. Laser Wire beam size monitor.6. Laser Wire beam size monitor. Fast sweep LW at EXT-line, Shintake-monitor at ATF2.• 7. Fast orbit feedback for ILC collision point.7. Fast orbit feedback for ILC collision point. digital feedback method is under development.• 8. Many other instrumentation(ODR, XSR, LW@DR) 8. Many other instrumentation(ODR, XSR, LW@DR) • 9. S-band RF-gun study for stable injection into ATF-DR.9. S-band RF-gun study for stable injection into ATF-DR.• 10. Pol. positron generation R&D based on Compton scattering.10. Pol. positron generation R&D based on Compton scattering.• 11. Fast Ion Instability Measurement
• 12. Multi-bunch Instability Study
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7 ‘y’ BPMs: 3 upgraded & 4 original
Stored Beam – 10 minute time scale; ATF lifetime ~ few minutes
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32.7cm : correspondto rise/fall time of2.2nsecFast pulse PS :<1nses<3.2nsec
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Construction plan of ATF2
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Highlight Studies in Extraction Line • Stable beam extraction from DR
– Kick angle compensation for multi-bunch, Double kicker system
– Multi bunch extraction with ILC like beam spacing (2005~)
– 3 bunch extraction with 150ns spacing by 300ns flat-top double kicker.
• Instrumentation developments
– Beam size monitors
Optical Diffraction Monitor, Wire scanners (Tungsten, Carbon), Laser wire (UK, 2005~)
– Nano meter resolution Beam position monitors : Cavity BPM
• Intra-train beam feedback
– FONT (UK) / FEATHER (KEK)
– Feed-forward to Extraction line from DR (UK, 2006~)
• Other R&D
– Polarized positron generation
Compton scattering with electron beam and polarized laser
– Stabilization of components , Straightness monitor, StaFF (UK, 2006~)
(Stabilization of the Final Focus of the ILC)
• More new R&D in ATF will be proposed.
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Two sets of triplets (z ~ 6m):
SLAC/US/UK tripletKEK triplet
Plan to test each individually – then connect (2006)
Present results from both!
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FFTB IP C-band cavity BPM triplet – this is the way to test BPM performance…
T. Shintake - 1998
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• 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 - SLAC
250 pulse sequence
+/-
20
um r
ange
of
mot
ion
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Move BPM in 1 um Steps
SLAC etc. – upstream triplet – 17 nm resolution
resi
dua
l
Development of Cavity BPM - KEK• System
– Three Cavity BPMs developed in KEK
– Mover system with an active stabilization using an optical interferometer
– Analog down conversion and phase detection electronics
PerformanceResolution of the BPM: 17nmActive mover stabilizes the system better than the resolution
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ATF Laser-wire•Goal: •At ATF, we will aim to measure micron-scale electron spot-sizes with green (532 nm) light.
• Aim at intra-train (fast) scan for 150 ns bunch spacing.
• The final spot-size measurable at ILC will have implications for the length and layout of the BDS diagnostics section. • The ATF/ATF2 results will be crucial to determine the technical boundaries.
pulsed laser-wire location
BESSY, DESY, Oxford, Royal Holloway, UCL, CCLRC, KEK, Kyoto, SLAC
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ATF-LW Vacuum Chamber
Built atOxfordDO +Workshop
VacuumTestedAt DL
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ATF Laser-wire
Vacuum chamber built in Oxford and Installed in ATF extractionLine in December 2006.
Laser lighttransported toIP, but nocollisions yet seen; probablya detector issue.
New run plannedFor April 06.
Designingdiagnosticsinsertionat Oxford
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LW Practical Considerations
f1 geometry is challenging• Limitations from power• Limitations from angle• Surface optical quality• Alignment tolerance
f1 Lens design is challenging• Limitations from power• Limitations from ghost images• Alignment tolerance• Lens currently under construction
37In this week, we measured this profile including laser size and beam size.
2nd LC Review, 7/28/2005 38
Feedback On Nanosecond Timescales (3)
Adjustable-gap kicker
BPM ML11X
Feedback
SuperfastBPM processor
Superfastamplifier
BPM ML12X
BPM ML13X
Aim:
TOTAL latency
< 20 ns
Oxford, DESY, CCLRC, KEK, Tokyo Metropolitan, SLAC
ATF extraction line beam direction
2nd LC Review, 7/28/2005 39
FONT3: Results (June 3 2005):Delay-loop feedback w. latency 23 ns
56ns bunchtrain
FB on
FB + delay loop on23ns
200um
2nd LC Review, 7/28/2005 40
FONT1,2,3: Summary67 ns
54 ns
23 nsEven fast enough for CLIC intra-train FB!May also be used at ILC
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Q-BPM for ATF2 by PAL
Beam signal test : OKQBPM with Cu-beam chamberAre under fabrication by PAL.
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Prospect of ATF • ATF International R&D will generate
necessary results for ILC, especially how to control high quality beam, develop many kinds of advanced instrumentation, educate young accelerator physicists and engineers.
• ILC like beam which means 20 bunches with bunch spacing about 300nsec, in the future.
• Realization of about 35nm beam for long period.
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2005.3.9
From US, EU, Russia, China, Korea, India and Japanese Univ.,Many young physicists and engineers are learning and developing advanced accelerator technologies for ILC project.
ATF Control Room