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ATF Status LCPAC 2005.02.25 K.KUBO

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

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ATF Status LCPAC 2005.02.25 K.KUBO

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  1. ATF StatusLCPAC2005.02.25 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. ATF: Accelerator Test FacilityPrimarily for LC study Extraction Line Damping Ring Electron Linac E=1.3GeV Ne=1x1010 e-/bunch 1 ~ 20 bunches/train 1 ~ 3 trains/ring Linac

  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 in the damping ring measured by Laser wire y/x emittance ratio <0.5% (gey ~ 1.5E-8 m) is constantly achieved in single bunch operation.

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

  6. Effect of ‘scrubbing’ Vertical beamsize vs. bunch number No big blow up of the tail bunches after ‘scrubbing’. But emittance tuning was not sufficiently good. After ‘scrubbing’ 5.5 A hour • 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.

  7. Vertical emittance of extracted beam 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 vs. bunch population. Emittance in DR was measured by Laser wire, in extraction line by wire scanners.

  8. Wiggler study Started in Oct. 2005. Basic performance with wigglers damping times emittances Effects of non-linear field of wigglers. dynamic aperture Total Length 2.0 m One period 0.4 m Full gap 20 mm Bpeak 1.62 T (1000A) Beff 1.40 T (1000 A) Current/pole 20 KA (20 turns) Number of poles 9(full) + 2(half) Correction of end poles.

  9. Damping time with/without wigglers (preliminary). Horizontal beam size vs. time. (Extracted beam.) with wiggler without wiggler

  10. Horizontal and Vertical emittance w/wo wigglers. Small vertical emittance was achieved both with and without wigglers. Horizontal emittance with wigglers was smaller than that without wigglers, as expected.

  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. with wiggler without wiggler  Beam life time (S)  nx

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

  14. T.Omori

  15. Measured Asymmetry and polarization of e+ preliminary A= +0.71± 0.23 % Laser polarity Magnet polarity A= -1.1± 0.23 % Laser polarity Magnet polarity Pol(e+)=99± 22% statistical error only T.Omori

  16. ODR (Optical Diffraction Radiation) study at ATF

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

  18. Comparisonof 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. A new technique for beam size measurement using ODR from a ‘dis-phased’ target. ODR by P.Karataev 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

  20. Pulse Laser Wire (K.Takezawa) Pulse Stacking Laser Wire Test in ATF DR 714MHz (21cm) Optical resonator cavity (Cavity length should be controlled ~1nm for resonance) Laser Pulse. l=1064 nm Pulse length = 2 mm Repetition 357MHz (Spacing should be controlled ~ 1 mm for pulse stacking) Scattered Photon (Detected) Penetrated light: Monitored for cavity length feedback Electron beam: bunch spacing 1/357 MHz (2.8 ns) Mirrors: optical resonator Compton Scattering, 357MHz Application • High intensity hard X-ray source • Beam monitor

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

  22. Pulse Laser Wire (K.Takezawa) Electron bunch length was measured. Count rate vs. Timing Count (Hz/mA) 1000 Bunch length 800 600 (Laser pulse length ~ 2 mm << electron bunch length) 400 200 0 40 80 120 140 200 RF system of Damping Ring (Define electron bunch timing.) Laser Timing (ps) • Proof of principle of enhancement of pulse laser by resonator • was done.For practical use, higher intensityis necessary. • Optical cavity with amplification factor 500, waist size 50 mm is designed. (present cavity: factor 50, waist size 250 mm)

  23. 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

  24. Cavity BPM Study 2 cavity BPM triplets in the ATF Extraction line A cavity triplet is used to determine resolution US KEK 2 x 600 mm triplets of cavity BPM’s; spacing ~ 5 m. M.Ross

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

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

  27. Long term stability (for 1 hour) - average residual of 40 sets of pulse sequences (4e3 pulses total); rms offset drift = 44 nm. 200 nm M.Ross

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

  29. Fast FB (Intra-pulse orbit feedback)International Collaboration • 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) UK LCABD Collaboration LCPAC2005, KEK 25/02/05

  30. Adjustable-gap kicker BPM ML11X BPM ML12X BPM ML13X Superfast amplifier Superfast BPM processor Feedback 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 beam Correct orbit of tail bunches using information of head bunches UK LCABD Collaboration LCPAC2005, KEK 25/02/05

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

  33. Summary-1 ATF is intended to: • generate the low emittance beam needed for the linear collider and • test the required precision control and monitoring technology • Low emittance beam that needed in LC was demonstrated • Typical damped beam ey: 4 pm-rad, gey: 0.1 nm-rad at 1.3 GeV (typical beam size = 5 µm) • (emittances required in the TESLA design: ey: 2 pm-rad, gey: 0.2 nm-rad at 5 GeV) • Multibunch operation and extracted beam have problems. M.Ross, K.Kubo

  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. 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. ATF Plans for 2005 • 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’

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