1. 1 ATF Status LCPAC 2005.02.25 K.KUBO Introduction Emittance Single bunch and multi-bunch in DR Extracted beam Wiggler study Other experiment, Instrumentation development, etc. Polarized positron production Optical Diffraction Radiation Laser Wire Cavity BPM Intra train Feedback,,,,,

2. 2 ATF: Accelerator Test Facility Primarily for LC study Electron Linac Extraction Line Linac Damping Ring E=1.3GeV Ne=1 x 10 10 e-/bunch 1 ~ 20 bunches/train 1 ~ 3 trains/ring

3. 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. 4 Single bunch Transverse Emittance y/x emittance ratio <0.5% (  y ~ 1.5E-8 m) is constantly achieved in single bunch operation. in the damping ring measured by Laser wire

5. 5 Multibunch Vertical Emittance in the damping ring measured by Laser wire Laser wire measures projected profile of many turns. Oscillation is appeared to be beam size blow up. Schematic of the Fast-Beam Ion Instability Fast beam ion instability simulation (by T.Raubenheimer)

6. 6 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

7. 7 Extracted beam emittance is larger than in the damping ring. Unknown higher order fields in the kickers and the septum magnets are suspected. (Kicker will be replaced in this summer.) Vertical emittance of extracted beam Vertical emittance vs. bunch population. Emittance in DR was measured by Laser wire, in extraction line by wire scanners.

8. 8 Wiggler study Correction of end poles. Started in Oct. 2004. Basic performance with wigglers damping times emittances Effects of non-linear field of wigglers. dynamic aperture Total Length2.0 m One period0.4 m Full gap20 mm Bpeak1.62 T (1000A) Beff1.40 T (1000 A) Current/pole20 KA (20 turns) Number of poles9(full) + 2(half)

9. 9 Wiggler offcalc.Wiggler oncalc.  x (ms) 19.3 + - 0.6317.515.7 + - 0.3814.2  y (ms) 28.8 + - 1.528.525.4 + - 0.6721.1  z (ms) 21.4 + - 3.920.514.2 + - 2.414.0 Damping time with/without wigglers (preliminary). Horizontal beam size vs. time. (Extracted beam.) without wiggler with wiggler

10. 10 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.

11. 11 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  Beam life time (S)

12. 12 Other Beam studies Compton-based Polarized Positron production ODR (Optical Diffraction Radiation for beam monitors) FEATHER(KEK)/FONT(QMUL) (intra-pulse orbit feedback) 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,,,,,)

13. 13 Polarized gamma-ray production by Polarized Laser light – electron collision Polarized positron production experiment T.Omori ATF extraction line

14. 14 T.Omori

15. 15 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 polarity Magnet polarity statistical error only T.Omori [Turned out to be e - ]  proportional to Number of transmitted gamma-rays

16. 16 ODR (Optical Diffraction Radiation) study at ATF extraction line

17. 17 Measurements of the ODR projected vertical polarization component using a photomultiplier (PMT) and comparison with the theory Detector acceptance ODR Intensity and angular distribution of ODR was consistent with calculations. ODR by P.Karataev Beam size is evaluated from bottom/top ratio. calculation

18. 18 Comparison of the beam sizes measured with ODR and wire scanners Correlation between the the ODR and the beam size measured with 10  m 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

19. 19 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. ODR geometry ODR interference pattern that could be observed with a CCD ODR by P.Karataev

20. 20 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 nm Pulse 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 DR Pulse Laser Wire (K.Takezawa) Mirrors: optical resonator to enhance photon intensity

21. 21 Damping Ring 12.7 m 4.8 m electron Laser wire Collimetor: 0.2mrad -> photon energy 12 ~ 14.5 MeV Detector Background subtraction Pulse Laser Wire (K.Takezawa) Enhancement by factor 50 was confirmed. = CW laser by factor 10000

22. 22 Electron bunch length was measured. Laser Timing (ps) 02008040120140 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 resonator was 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 )

23. 23 UK: Pulsed Laser-wire at the ATF Extraction Line University of Oxford: N. Delerue, B. Foster, D. Howell, A.Reichold I. 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

24. 24 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

25. 25 Cavity BPM nm resolution study (US) LLNL Design frame Should be very rigid; relative position jitter due to vibration < nm.

26. 26 Cavity BPM resolution tests: Residual of center BPM wrt predicted position from 1 st and 3 rd. Rms <20 nm for 600 pulses Plot scale is +80 / -60 nm (results from 12.04; first commissioning run) M.Ross BPM resolution = rms*sqrt(2/3)  17 nm

27. 27 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

28. 28 Y.Honda Totally different idea of support and position control. (KEK)

29. 29 UK 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

30. 30 UK 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 Feedbac k Superfast BPM processor Superfast amplifier BPM ML12X BPM ML13X Correct orbit of tail bunches using information of head bunches beam ATF extraction line

31. 31 FONT3 BPM processor (single-bunch data from December 2004 beam tests) Latency ~ 4 ns BPM UK LCABD Collaboration LCPAC2005, KEK 25/02/05

32. 32 UK 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

33. 33 ATF is intended to: 1.generate the low emittance beam needed for the linear collider 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 problems. Summary-1 M.Ross, K.Kubo

34. 34 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

35. 35 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

36. 36 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’