1. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Plans for FONT3 and Future Feedback Experiments Philip Burrows Queen Mary, University of London ILC system overview FONT2 @ NLCTA: reminder FONT3/FEATHER plans at ATF Future feedback experiments

2. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT: Queen Mary: Philip Burrows, Glen White, Glenn Christian, Hamid Dabirikhah, 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: Nicolas Delerue, Toshiaki Tauchi, Hitoshi Hayano Tokyo Met. University: Takayuki Sumiyoshi, Fujimoto Simulations: Nick Walker (DESY), Daniel Schulte (CERN) International Fast FB Collaboration

3. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Beam-based feedback in ILC ‘Slow’ orbit (upstream BDS, linac) Pulse-to-pulse (ILC: 5 Hz): extensive experience at SLC (120 Hz) Intra-train (‘bunch-to-bunch’): principal correction scheme in TESLA TDR Integrated simulations linac -> IP + ground motion, wakefields … (PLACET, LIAR, MERLIN, GUINEAPIG, CAIN) Hardware prototyping of (fast analogue) critical components: BPM processors, FB, drive amplifiers + closed-loop beam tests

4. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Intra-train Beam-based Feedback Intra-train beam feedback is last line of defence against relative beam misalignment Key components: Beam position monitor (BPM) Signal processor Fast driver amplifier E.M. kicker Fast FB circuit TESLA TDR: principal IR beam-misalignment correction

5. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Zero-degree crossing angle (TESLA TDR) FB BPM Upstream kicker(s)

6. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 ‘Large’ crossing angle (NLC) FB BPMkicker

7. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Intra-train feedback performance (White/QMUL) y position FB: restore collisions within 100 bunches 1 seed: post-BBA + GM + wakes y position scan: optimise signal in pair monitor (+4%) y angle scan OPTIMAL LUMINOSITY

8. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 (FONT1 +) FONT2: beamline configuration Dipole and kickers BPMs

9. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT1 + FONT2 amplifiers Bandwidth limited (30 MHz) FONT1 3-stage tube ampFONT2 solid-state amp Up to 10A, 350V Up to 10A, 100V (x2)

10. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT2: expected latency Time of flight kicker – BPM: 6ns Signal return time BPM – kicker: 10ns Irreducible latency: 16ns BPM processor: 18ns FB circuit: 4ns Amplifier: 12ns Kicker fill time: 3ns Electronics latency: 37ns Total latency expected: 53ns

11. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT2 results: feedback BPM Feedback on Beam flattener on Beam starting positions Delay loop on beam startbeam end 123 4

12. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT2 final results (Jan 22 2004) Super-fast modified configuration: Latency 54ns Correction 14:1 (limited by gain knob resolution) dispersion

13. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 Original aim: Demonstrate micron-level stabilisation of 1.3 GeV ATF beam with latency c. 20 ns EQUIVALENT TO: nanometer stabilisation of 250-500 GeV LC beam with same lever arm … -> demonstrate actual BPM processor and amplifier for warm LC Worth completing, though low latency no longer critical

14. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 outline Adjustable-gap kicker BPM ML11X Feedbac k Superfast BPM processor Superfast amplifier BPM ML12X BPM ML13X Aim: TOTAL latency < 20 ns

15. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3: latency budget Time of flight kicker – BPM: 4ns Signal return time BPM – kicker: 6ns Irreducible latency: 10ns BPM processor: 5ns Amplifier + FB: 5ns Electronics latency: 10ns Total latency budget: 20ns Will allow 56/20 = 2.8 periods during bunchtrain

16. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3: beamline configuration kicker BPM ML11X

17. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 BPM processor (Molloy) Latency budget 5ns Superfast scheme: down-mix to baseband using 714 MHz LO First tests June 2004 Now testing improved scheme w. different filter options Final version ready for March 2005

18. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 amplifier (Perry) Detailed design in progress Tradeoff between drive and latency latency < 5 ns constrains drive significantly Lever-arm amplifier -> BPM very small: c. 1.1m Solid state, low power ( < 100W) Aiming for beam kick up to 20-30 microns at ML11X First version will be tested in March 2005 Slightly improved version possible for June 2005

19. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 DAQ/control (White) Almost certainly use our 2 scopes (8 channels): FB BPM output drive signal to amplifier 2 witness BPM y signals Delay loop signal 2 witness BPM y signals … Auto control of corrector (ZV7X?) to produce controlled incoming beam offsets at FB BPM

20. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 beam requirements 20-bunch train (56 ns) essential in order to see action of delay loop Uniform charge within train (better than +- 10%) essential since no time for charge normalisation Flat bunch-bunch position profile within train desirable Small bunch-bunch position jitter within train (few microns) essential Small train-train jitter (few microns) essential to avoid amplifier saturation (c. 20 microns)

21. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 FONT3 jitter monitor (Kalinin) Aim to measure bunch-bunch jitter at micron level First tests June 2005: bunches resolved, but position resolution > 10 microns (common-mode rejection issues) Improved processors being tested now (BPMs 8, 10, 13) + 2 BPMs in ring

22. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Possible Future Experimental Programme (1) Short-term: expect to finish FONT3 in June 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 > 2006 (?): 20 bunches x 337ns at ATF/ATF2 would be very attractive 2005-6: 3 (or 4) bunches x 100 ns at ATF would also be interesting: stabilise last bunch at 100 nm level as part of Nano project also feed-forward studies ring -> extraction line?

23. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 2006: ‘Nano’ Project at KEK ATF FONT/FEATHER-style feed-forward and/or feedback

24. Philip Burrows 2 nd Nano Workshop, KEK 11/12/04 Possible Future Experimental Programme (2) Study of performance of FB hardware in realistic IR environment: e+e- and gamma backgrounds Make e+e- and gamma fluxes in SLAC A-line: install BPM and study noise/long-term radiation effects Concerns about EM pickup in FB BPM – test in IR mockup? Intra-train beam feedback technology widely applicable: emergency fast beam abort (DONT)? beam position stabilisation for diagnostics: laserwire, bunch-length monitor, Shintake monitor …