1. 1 Feedback On Nanosecond Timescales (FONT): Philip Burrows Neven Blaskovic, Douglas Bett, Glenn Christian, Michael Davis, Young Im Kim, Colin Perry John Adams Institute Oxford University IP Feedback

2. 2 Outline Reminder of CLIC IPFB prototype Remarks on L* ATF2 IP FB concept Results of recent beam runs

3. 3 IP beam feedback concept Last line of defence against relative beam misalignment Measure vertical position of outgoing beam and hence beam-beam kick angle Use fast amplifier and kicker to correct vertical position of beam incoming to IR FONT – Feedback On Nanosecond Timescales

4. CLIC Final Doublet Region 4

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7. 7 Comments on L* Current geometry: time of flight IP  BPM  kicker  IP ~ 24 ns Demonstrated FONT3 electronics latency = 13ns Estimated IPFB latency = 37ns

8. 8 CLIC IP FB performance Single random seed of GM C Resta Lopez

9. 9 For noisy sites: CLIC IP FB performance  factor 2 - 3 improvement

10. 10 Comments on L* Current CDR geometry: time of flight IP  BPM  kicker  IP ~ 24 ns Demonstrated FONT3 electronics latency = 13ns Estimated IPFB latency = 37ns In principle, change of L* need not affect IPFB position and latency, but needs to be engineered carefully, considering other beamline components

11. CLIC Final Doublet Region 11

12. FONT5 installation at ATF2 ATF2 extraction line 12

13. 13 IP kickerIPBPMs FONT digital FB IPBPM electronics FONT amplifier e- ATF2 IP FB loop scheme Eventual goal is to stabilise the small ATF2 beam (design 37nm) at the nanometer level

14. 14 Nanometer beam FB at ATF2 IP Much harder than IPFB at ILC or CLIC! Only 1 beam  must measure beam position directly nm-level stabilisation requires nm-level position meas.  Cavity BPMs (rather than striplines) Cavities intrinsically slow, signal processing complicated Cavities required to resolve 2 bunches within << 300ns  Low-Q cavities and low-latency signal processing  New BPMs+electronics (KNU), new IP chamber (LAL)

15. 15 Layout with new IP kicker Designed by Oxford Fabrication arranged by KEK

16. 16 IP kickerIPBPMs FONT digital FB IPBPM electronics FONT amplifier e- Preparatory tests June 2013 Existing IPBPMs Honda low-latency electronics

17. 17 Preparatory test setup A B

18. Preparatory test IPFB loop Analogue Front-end BPM processor FPGA-based digital processor Kicker drive amplifier Strip-line kicker Beam Cavity BPM 18

19. IP Feedback Results FB Off Jitter: 170 ± 10 nm FB On Jitter: 93 ± 4 nm FB Off Correlation: 81% 19

20. IP Feedback Results FB Off Jitter: 170 ± 10 nm FB On Jitter: 93 ± 4 nm FB Off Correlation: 81% FB On Correlation: -16% 20

21. Incoming Beam Position Scan 10 μm pos. scan Bunch 2

22. 22 IP BPM resolution Beam size during measurements ~ 100 nm Model  beam jitter ~ 20% of beam size, i.e. 20nm Assuming results are resolution limited … Resolution = 93 nm / sqrt(2) ~ 65 nm (no direct resolution measurement possible)

23. 23 New IP chamber installed summer 2013 Commissioning Started November: alignment, BPM signals

24. 11cm Low-Q IP-BPM design 11cm Low-Q IP-BPM drawings of HFSS 100mm Sensor cavity Wave guide Antenna Designed frequency X-port: 5.712 GHz Y-port: 6.426 GHz Full size : 11cmx11cm (to install IP-Chamber) Light weight: 1 kg (Single cavity) 2 kg (Double cavity)

25. 25 In May tests resumed w. Honda electronics FF quad current scan to set vertical beam waist at IPB

26. 26 In May tests resumed w. Honda electronics Centre beam in BPM using mover  optimise resolution

27. 27 In May tests resumed w. Honda electronics Centre beam in BPM using mover  optimise resolution

28. 28 Summary ATF2 IPFB prototype is progressing Beam stabilised (June 2013) to ~ 100nm level Beam jitters measured (June 2014) ~ 60nm (best) Beam studies continue until June 20 th Attempting to disentangle jitter/resolution Looking at boosting signal levels  resolution Hope to close FB loop with improved resolution