ATF: The Unique Test Facility for ILC with Low Emittance Beam

1. Special Lecture- ATFThe 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

2. 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 overseas institutes were involved. • ATF MoU was established on 1st Aug. 2005. New organized ATF international collaboration has been 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 school. • From 2008, ATF2 : the final focus test beam line, will be operated.

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

4. Assignment of the ATF Beam Time Typical ~22 weeks/year About 20 % of total will be used for the maintenance and the beam tuning. It is estimated by current results. Maintenance Beam Tuning • Guideline for approved studied by SP. • Short term study • No conflict with approved studies • by TB and ICB. • Test study for new proposal • SP can accept until two shifts/week • but it depends on the situation of • studies. SP: Approved Studies TB: Approved Studies ~2/3

5. Schedule of ATF operation, TB meeting and Long shutdown

6. Mission of ATF Establish the technologies associated with producing the electron beams of the quality required for ILC. Provide such beams to ATF2 in a stable and reliable manner. Serve the mission of providing the young scientists and engineers with training opportunities of participating in R&D programs for advanced accelerator technologies.

7. Introduction ATF Accelerator Test Facility

9. 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 1010 electrons / bunch

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

11. Beam dynamics study 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(?) % Single bunch Measured in DR

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

13. 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

14. R&D Programs and ATF2 • 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. <3ns rise/fall is under study. • 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. nm resolution BPMs, PAL-BPM at ATF2, IP-BPM at ATF2. • 6. Laser Wire beam size monitor. Fast sweep LW at EXT-line, Shintake-monitor at ATF2. • 7. Fast orbit feedback for ILC collision point. digital feedback method is under development. • 8. Many other instrumentation(ODR, XSR, LW@DR) • 9. S-band RF-gun study for stable injection into ATF-DR. • 10. Pol. positron generation R&D based on Compton scattering. • 11. Fast Ion Instability Measurement • 12. Multi-bunch Instability Study

15. 7 ‘y’ BPMs: 3 upgraded & 4 original Stored Beam – 10 minute time scale; ATF lifetime ~ few minutes

19. 32.7cm : correspond to rise/fall time of 2.2nsec Fast pulse PS :<1nses <3.2nsec

23. Construction plan of ATF2

24. 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.

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

29. Generic Cavity BPM Design: TM11-mode Selective Coupler • Dipole frequency: 11.424 GHz • Dipole mode: TM11 • Coupling to waveguide: magnetic • Beam x-offset couple to y port • Sensitivity: 1.6mV/nC/m • (1.6109V/C/mm) • Couple to dipole (TM11) only • Does not couple to TM01 • Low Q with narrow cavity gap • May need to damp TM01 • OR, use stainless steel to lower Q signal signal Z. Li

30. FFTB IP C-band cavity BPM triplet – this is the way to test BPM performance… T. Shintake - 1998

31. Calibration - SLAC • 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. +/- 20 um range of motion 250 pulse sequence

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

33. 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

34. 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. ATF Laser-wire pulsed laser-wire location BESSY, DESY, Oxford, Royal Holloway, UCL, CCLRC, KEK, Kyoto, SLAC

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

36. ATF Laser-wire Vacuum chamber built in Oxford and Installed in ATF extraction Line in December 2006. 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

37. 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

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

39. FONT3: Results (June 3 2005):Delay-loop feedback w. latency 23 ns 56ns bunchtrain 200um FB on 23ns FB + delay loop on

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

41. AIN4 AIN3 AIN2 AIN1 AOUT1 AOUT2 Clk IN FONT4: Digital FB Processor Module (Dabiri Khah) RAM Flash/ EEPROM JTAG circuit JTAG connector DAC DAC UART circuit Serial connector FPGA ADC Differential To single ADC Differential To single USB circuit USB connector ADC Differential To single Clock circuit ADC Differential To single IN Power Jack & switch 5v 3.3v 2.5v ? v Latency goal 100ns

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

43. Design of ATF2 IP-BPM

44. 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.

45. 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. 2005.3.9 ATF Control Room