Special Lecture- ATF The unique test facility for ILC with a low emittance beam. Junji Urakawa, KEK ILC School at KEK History and Machine introduction 2. Machine performance 3. R&D Programs and ATF2 4. Highlight Studies in Extraction Line

1 ATF Collaboration History ATF Construction and R&D’s have been started with SLAC from From 1997 International collaboration was started for the R&D’s with Damping Ring. Many overseas institutes were involved. ATF MoU was established on 1 st Aug New organized ATF international collaboration has been started. (20 Institutes or more were signed.) 1 st ICB meeting in Snowmass, 1 st TB meeting at KEK on Dec.. 2 nd TB meeting will be scheduled in May after ILC school. From 2008, ATF2 : the final focus test beam line, will be operated.

2 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 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 overseas countries and, young scientists and engineers can learn how to make the good beam.

3 Assignment of the ATF Beam Time TB: Approved Studies ~2/3 SP: Approved Studies Beam Tuning Maintenance Typical ~22 weeks/year About 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 study 2.No conflict with approved studies by TB and ICB. 3.Test study for new proposal 4.SP can accept until two shifts/week but it depends on the situation of studies.

4 Schedule of ATF operation, TB meeting and Long shutdown

5 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.

6 Introduction ATF Accelerator Test Facility

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8 Machine performance Look 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 electrons / bunch

9 Laser wire scanner in DR for X & Y scan, for single/multi-bunch TEM00 wire TEM01 wire Two optical cavity chamber For X-wire and Y-wire

10 Possibility of 1pm-rad  y Kubo's simulation: BPM offset error should be < 0.1 mm. (“BBA”) Then, ε y ~ 2 pm will be achieved. Magnet re-alignment, < 30 μm. Then, ε y ~ 1 pm will be achieved. Optics model should be good. Quad strength error should be < 0.5(?) % Measured in DR Single bunch Beam dynamics study

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

12 Maximum energy1.28 GeV (γ=2500) Beam emittance Vertical (1.5 ± 0.25)  m rad Horizontal (1.4 ± 0.3)  m rad Bunch Length~9mm (30 ps) Single bunch population 2.0  Energy Spread0.08% 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

13 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. kicker study for ILC Damping Ring.2. Fast rise/fall strip-line 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, Many other instrumentation(ODR, XSR, 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

14 7 ‘y’ BPMs: 3 upgraded & 4 original Stored Beam – 10 minute time scale; ATF lifetime ~ few minutes

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cm : correspond to rise/fall time of 2.2nsec Fast pulse PS :<1nses <3.2nsec

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22 Construction plan of ATF2

23 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~) More new R&D in ATF will be proposed.

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27 Two sets of triplets (z ~ 6m): SLAC/US/UK triplet KEK triplet Plan to test each individually – then connect (2006) Present results from both!

28 Generic Cavity BPM Design: TM 11 -mode Selective Coupler Dipole frequency: GHz Dipole mode: TM 11 Coupling to waveguide: magnetic Beam x-offset couple to y port Sensitivity: 1.6mV/nC/  m (1.6  10 9 V/C/mm) Couple to dipole (TM 11 ) only Does not couple to TM 01 –Low Q with narrow cavity gap –May need to damp TM 01 –OR, use stainless steel to lower Q signal Z. Li

29 FFTB IP C-band cavity BPM triplet – this is the way to test BPM performance… T. Shintake

30 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 range of motion

31 Move BPM in 1 um Steps SLAC – upstream triplet – 17 nm resolution residual

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 Performance Resolution of the BPM: 17nm Active mover stabilizes the system better than the resolution

33 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

34 ATF-LW Vacuum Chamber Built at Oxford DO + Workshop Vacuum Tested At DL

35 ATF Laser-wire Vacuum chamber built in Oxford and Installed in ATF extraction Line in December Laser light transported to IP, but no collisions yet seen; probably a detector issue. New run planned For April 06. Designing diagnostics insertion at Oxford

36 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

37 Feedback On Nanosecond Timescales (3) Adjustable-gap kicker BPM ML11X Feedbac k Superfast BPM processor Superfast amplifier BPM ML12X BPM ML13X Aim: TOTAL latency < 20 ns Oxford, DESY, CCLRC, KEK, Tokyo Metropolitan, SLAC ATF extraction line beam direction

38 FONT3: Results (June ): Delay-loop feedback w. latency 23 ns 56ns bunchtrain FB on FB + delay loop on 23ns 200um

39 FONT1,2,3: Summary 67 ns 54 ns 23 ns Even fast enough for CLIC intra-train FB! May also be used at ILC

40 FPGA DAC ADC Differential To single AIN4AIN3AIN2AIN1 AOUT1AOUT2 RAM Clock circuit JTAG circuit USB circuit UART circuit IN Power Jack & switch 5v2.5v? v3.3v JTAG connector Serial connector USB connector Flash/ EEPROM Clk IN Differential To single Differential To single Differential To single FONT4: Digital FB Processor Module (Dabiri Khah) Latency goal 100ns

41 Q-BPM for ATF2 by PAL Beam signal test : OK QBPM with Cu-beam chamber Are under fabrication by PAL.

42 Design of ATF2 IP-BPM

43 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.

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