Beam Measurements and Corrections at 10th ATF2 Project Meeting (June 30, 2010)

Detailed discussions on beam measurements, corrections, dispersion, coupling, and beta matching were presented at the 10th ATF2 Project Meeting. Various parameters, emittance, coupling measurement, and correction methods were examined, highlighting the importance of precise alignment and adjustments for optimal beam performance.

• Beam Measurements
• Corrections
• Dispersion
• Coupling
• Beta Matching

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1. EXT Beam Measurements & Corrections Dispersion, Coupling, Beta Matching 10th ATF2 Project Meeting, June 30 2010 M. Woodley 1/31

2. ATF / ATF2 Schematic Layout 30 20 Emittance Measurement 5 WS, 4 OTR 10 W wires (x/y/+10 /-10 ) Final Doublet Coupling Correction 10 Final Focus -match Dump Inflector Laserwire EXT 0 INJ Laserwire PIP WS 10 W wires (x/y/45 ) 5 C wires (y/+1.3 /-1.3 ) IPBSM 10 W wires (x/y) screen -10 X (m) Damping Ring Beam Transport FOBO -20 XSR e- -30 S-band RF Gun 1.3 GeV S-band Linac -40 120 m 10th ATF2 Project Meeting, June 30 2010 M. Woodley 2/31 -50 -60 -100 -80 -60 -40 Z (m) -20 0 20

3. Parameters parameter design May 2010 unit frep Q 1.56 1.56 Hz Injector system and Damping Ring can provide single-bunch beam or multi-bunch beam up to Q=2 1010 1-20 bunches per train 1, 2, or 3 trains 109 e-/bunch 2-10 ~5 E 1.3 1.282 GeV 10-6 m x (DR) y (DR) x (EXT) y (EXT) z x* y* 'x* x* y* 3.0 4.8 10-8 m 3.0 3.1 1.2 1.9 nm 12.0 12.5 pm Minimum Damping Ring emittances achieved (c.2004) x = 1.5 nm y = 4 pm Y. Honda, et al., PRL92(2004)054802 8 8 mm 0.08 0.08 % 4.0 40.0 mm 0.1 1.0 mm 0.1394 0.1394 rad 2.2 8.7 m 37 112 nm 10th ATF2 Project Meeting, June 30 2010 M. Woodley 3/31

4. EMITTANCE & COUPLING MEASUREMENT & CORRECTION 10th ATF2 Project Meeting, June 30 2010 M. Woodley 4

5. XSR y ~ 5 m SRIF y ~ 5 m LW 00 mode y = 4.1 m ATF2 design 01 mode y = 3.2 m 10th ATF2 Project Meeting, June 30 2010 M. Woodley 5/31

6. QM7R: pole-tip radius = 16 mm extracted beam offset = 22.5 mm Tokin 3393 ( = 32 mm) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 6/31

7. QM7R replaced with larger bore ( = 42 mm) quadrupole in January 2009 K1L = 0.3 m-1 = 0.76 nominal optics mismatch K2L = 46.6 m-2 x-y coupling for vertically off-axis beam: factor ~ 2-3 y for y = 1 mm ( x: y = 100:1) K1L = 0.392 m-1 = 0.99 nominal K2L = 1 m-2 Measured PRIAM simulation K0L K1L K2L Tokin 3393 ( = 32 mm) Tokin 3581 ( = 42 mm) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 7/31

8. Observed that first 2 EXT vertical correctors (ZV1X and ZV2X) needed to be strong to properly launch into EXT (since before EXT rebuild for ATF2 ) hypothesize that correctors are compensating for a kick error in extraction channel simulate error kick by rolling individual elements; use ZV1X and ZV2X to correct orbit find error that gives best fit to actual ZV1X/ZV2X values BS3X septum magnet roll BS3X was physically rolled ~ -4 mrad (March 17, 2010) to relieve ZV1X and ZV2X projected vertical emittance in EXT before coupling correction was improved (~20-40 pm before ~10-20 pm after) BS3X roll = 4.66 mrad ZV100RX QD2X QS1X QF1X QF3X ZV1X ZV2X ZV3X SET-file values (April 2009 - May 2010) QM6R QM7R BH1X KEX1 BS1X BS2X BS3X 1.4 1.2 0.2 1 0 0.8 -0.2 0.6 ZV2X Current (A) -0.4 Y (mm) 0.4 -0.6 0.2 -0.8 0 -1 -0.2 -1.2 0 2 4 6 8 10 12 14 S (m) -0.4 BS3X roll = 4.66 mrad Izv1 = -6.918 (-6.976) amp Izv2 = 1.270 ( 0.965) amp chi2 = 0.3102 before March 17, 2010 after March 17, 2010 -0.6 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 ZV1X Current (A) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 8/31

9. Horizontal EXT Emittance Measurements Vertical EXT Emittance Measurements Date Nwire Emit (pm) BMAG Date Nwire Emit (nm) BMAG May 18 2010 5 11.7 2.3 1.43 0.25 May 18 2010 4 1.905 0.078 1.08 0.03 Apr 21 2010 5 15.4 2.0 1.78 0.17 Apr 21 2010 4 1.212 0.065 1.26 0.03 Mar 17 2010 BS3X rolled ~4 mrad (CCW) Mar 17 2010 BS3X rolled ~4 mrad (CCW) Feb 25 2010 5 38.33 1.1 1.10 0.02 Feb 25 2010 4 1.868 0.336 1.15 0.12 Feb 17 2010 5 22.6 1.4 1.15 0.04 Feb 17 2010 4 negative Feb 3 2010 5 16.1 0.7 1.06 0.03 Feb 3 2010 4 1.626 0.095 1.10 0.06 Jan 28 2010 5 31.6 1.2 1.03 0.01 Jan 28 2010 Dec 17 2009 5 28.4 1.7 1.01 0.01 Dec 8 2009 4 32.2 1.9 1.35 0.13 Dec 8 2009 3 2.921 0.129 1.05 0.03 Anomalous DR EXT vertical emittance growth fixed (?) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 9/31

10. EXT Diagnostic Section (version 4.2a) SQ SQ WS WS WS WS WS SQ SQ OTR OTR OTR OTR 20 x y 90 90 180 90 90 90 11 17 28 29 42 43 29 29 18 16 78.2 10.3 151.2 6.9 86.3 12.0 149.3 6.8 84.3 12.1 ( m) 14 12 Beta (m) ILC orthonormal coupling correction system 10 8 6 4 7 < x/ y < 22 2 10 wire orientation is optimal for beam tilt measurement 0 25 30 35 40 45 50 S (m) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 10/31

11. Coupling correction: single skew quadrupole scan EmitY (pm) projected vertical emittance ( y) reduced to 11.5 pm using QK1X required 57 individual wire scans per QK1X setting X (MW1X / MW2X / MW3X / MW4X) 3 Y (MW0X / MW1X / MW2X / MW3X / MW4X) 3 +10 (MW0X / MW1X / MW2X / MW3X / MW4X) 3 -10 (MW0X / MW1X / MW2X / MW3X / MW4X) 3 elapsed time: 7 hours for 5-point scan (!) need multi-OTR to speed up realistically: 90 minutes for one 5-point QK scan (4 Y wires 3 scans at each point) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 11/31

12. Coupling measurements in ATF2 EXT (1) [Cecile Rimbault] Projected beam size measurements at x, 80o, y and 100oat 4 wire-scanner positions varying the strength of the QK1X skew quadrupole Coupling reconstruction Coupling reconstruction using: 2 2 sin cos = 33 11 13 2 cos sin 2 sin cos * = 80 Verification of the consistency of 80oand 100o measurements = 100 Search for an algorithm to reconstruct the beam matrix at QK1X position: The more reliable method consists of: a. Constrain 6 elements with 33fits b. Constrain 3 elements with 13fits c. Constrain the last one with 11fits = + + + 2 33 2 34 2 M 33 QK 33 QK 34 QK 44 2 R R R R AB C 33 34 + + 2 34 QK 13 QK 14 2 ( ) 2 k R R R AB 33 34 + 2 2 34 QK 11 k R A = + + + + = + + + 2 M 13 QK 13 QK 14 QK 23 QK 24 )) 2 2 2 M 11 QK 11 QK 12 QK 22 2 R R R R R R R R + AB 2 C R R R R AB C 11 ( 33 11 34 33 12 12 34 11 11 12 12 + + + + + 2 QK 11 QK 33 QK 12 QK 34 QK 13 QK 23 ( 2 ( ) 2 k R R R R R R AB k R R R AB 11 34 12 33 12 34 11 12 12 + + 2 2 2 QK 13 QK 33 k R R A k R A 12 34 12 10th ATF2 Project Meeting, June 30 2010 M. Woodley 12/31

13. Coupling measurements in ATF2 EXT (2) [Cecile Rimbault] at QK1X Comparison between measurements and beam matrix reconstruction result propagation 33 13 - physical results but large error bars (not to mention imaginary y!) - large number of data sets is required to minimize statistical errors - analysis algorithm must guarantee positive-definite beam matrix 10th ATF2 Project Meeting, June 30 2010 M. Woodley 13/31

14. 4.All 4 OTRs installed as of June 1 5.Target inserters, movers, cameras, controls, software all OK 6.All 4 OTR targets melted during checkout! thin aluminized mylar target (1200 Al) Prosilica camera (3.75 m / pixel) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 14/31

15. ATF2 EXT OTR1 June 2, 2010 single bunch beam Q 4 109 e-/bunch (0.64 nC) 1.56 Hz x 140 m ; y 10 m 2 m nitrocellulose / 1200 Al ~4 minutes in beam until damage ok damaged targets will be replaced > 6 m kapton / 1200 Al > 100 m Al foil 10 m tungsten X/Y wires will be added to target holders scribe line melted pixels 10th ATF2 Project Meeting, June 30 2010 M. Woodley 15/31

16. DISPERSION MEASUREMENT & CORRECTION 10th ATF2 Project Meeting, June 30 2010 M. Woodley 16

17. Flight Simulator Dispersion Measurement / Correction 10th ATF2 Project Meeting, June 30 2010 M. Woodley 17/31

18. Horizontal Dispersion Correction Response Matrix Measurement Before Correction After Correction x 'x IQF1X (amp) IQF6X (amp) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 18/31

19. QM6R QM7R QD2X QD5X QD8X QF1X QF3X QF4X QF6X QF7X KEX1 KEX2 BH1X BH2X BH3X BS1X BS2X BS3X Vertical Dispersion Correction (FD-phase) QS1X QS2X 20 X Y 1/2 10 0 0.75 0.5 0.25 0 -0.25 -0.5 -0.75 1 0 -1 0 5 10 15 20 S (m) Sum-Knob : IQS1X = IQS2X Sum-Knob = -0.15 A IP-phase FD-phase Simulated y* (right) and 'y* (right), back-propagated from IP 10th ATF2 Project Meeting, June 30 2010 M. Woodley 19/31

20. Summary of Vertical Dispersion at IP 2010/ 2/ 18 10mm at IP The old orbit had a large offset around QF21X, QM16FF. I applied careful orbit tuning around QF21X, QM16FF with FF mover. 2010/ 2/ 25 1mm at IP We used the fast kicker for the beam extraction. 2010/ 3/ 18 2mm at post-IP We switched back to SLAC kicker. 2010/ 4/ 7 3.8mm at post-IP Dispersion for 4/7 QS1X= -1A QS2X= -1A 2010/ 4/ 8 3.6mm at post-IP 3.6mm at IP Dispersion for 4/8 QS1X= -2.8A QS2X= -2.8A IP dispersion is not sensitive to Sum-knob From Okugi-san s presentation (ATF Ops 2010.04.09) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 20/31

21. BETA MATCHING 10th ATF2 Project Meeting, June 30 2010 M. Woodley 21

22. Irwin Knobs ATF2 pulse-to-pulse feedback devices (v3.7) Final Focus QD10BFF QD10AFF QD4BFF QD4AFF QD2BFF QD2AFF QM16FF QM15FF QM14FF QM13FF QM12FF QM11FF QF9BFF QF9AFF QF5BFF QF5AFF QD8FF QD6FF QD0FF QD18X QD20X QF7FF SD4FF QF3FF QF1FF SD0FF QF19X QF21X SF6FF SF5FF SF1FF B5FF B2FF B1FF 0 -0.25 R0 -0.5 Irwin Knobs for -matching : R = RI R0 -0.75 -1 (rad/2 ) alpha knob beta knob phase knob -1.25 1 * 0 1 0 1 m m 0 1 0 cos sin sin cos s -1.5 RI = * 0 1 0 * * 0 -1.75 -2 phase shift ( * 0) waist shift magnification X Y -2.25 10th ATF2 Project Meeting, June 30 2010 40 45 M. Woodley 70 22/31 -2.5 50 55 60 65 75 80 85 S (m)

23. get initial magnet strengths from control system, compute R0 for a desired knob type, compute RI(n) for a small step in s, m, or small steps required due to nonlinear KLQ/ Knob set R=RI(n)*R0 to make one knob step use MAD matching to fit to desired elements of R using FF matching quadrupoles changes to magnet strengths tend to be symmetric in the knob value computed strengths for quadrupoles that start at zero tend to go bipolar tried waist shift and magnification knobs during tuning week seem OK 10th ATF2 Project Meeting, June 30 2010 M. Woodley 23/31

24. Vertical Waist Scan (5*) [BX10BY10 optics] IP Twiss Parameters QM*FF Currents (amps) 4.4 1 1 58 20.8 QM16FF (amps) QM15FF (amps) QM14FF (amps) 27.4 4.2 0.5 0.5 20.6 57 x (deg) x (cm) 20.4 4 0 0 x 20.2 27.2 56 20 3.8 -0.5 -0.5 19.8 27 55 19.6 -1 -1 -4 -2 0 2 4 -4 -2 0 2 4 -4 -2 0 2 4 -4 -2 0 2 4 -4 -2 0 2 4 -4 -2 0 2 4 37.5 25 4 10 17 QM13FF (amps) QM12FF (amps) QM11FF (amps) 20 0.2 2 5 37 y (deg) y (mm) 16 15 0 0 y 0 10 15 36.5 -2 -5 5 14 -0.2 -10 -4 36 -4 -2 0 2 4 -4 -2 0 2 4 Wy (mm) -4 -2 0 2 4 -4 -2 0 2 4 -4 -2 0 2 4 Wy (mm) -4 -2 0 2 4 10th ATF2 Project Meeting, June 30 2010 M. Woodley 24/31

25. Vertical Magnification Scan (0.5-2) [BX10BY10 optics] IP Twiss Parameters QM*FF Currents (amps) 4.4 1 1 24 29 65 QM16FF (amps) QM15FF (amps) QM14FF (amps) 4.2 0.5 0.5 22 x (deg) 28 x (cm) 60 4 0 0 x 20 27 55 3.8 -0.5 -0.5 18 26 -1 -1 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 1 1 QM13FF (amps) QM12FF (amps) QM11FF (amps) 20 0.5 0.5 1 38 1.5 y (deg) y (mm) 0 0 15 y 36 0 1 -0.5 -0.5 10 34 -1 0.5 -1 -1 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 0.5 1 1.5 2 My My * y = M M m y y y * y 0 10th ATF2 Project Meeting, June 30 2010 M. Woodley 25/31

26. Vertical Phase Scan (0-90) [BX10BY10 optics] IP Twiss Parameters QM*FF Currents (amps) 4.4 1 36 30 500 QM16FF (amps) QM15FF (amps) QM14FF (amps) 4.2 0.5 28 34 100 x (deg) x (cm) 26 32 4 0 0 x 80 24 30 3.8 -0.5 22 -500 28 60 -1 0 50 0 50 0 50 0 50 0 50 0 50 1 42 16 80 QM13FF (amps) QM12FF (amps) QM11FF (amps) 1.5 1.05 0.5 14 60 y (deg) y (mm) 40 1 1 0 12 y 40 0.5 10 0.95 -0.5 20 38 8 0 0.9 -1 0 0 50 0 50 0 50 0 50 0 50 0 50 y (deg) y (deg) 10th ATF2 Project Meeting, June 30 2010 M. Woodley 26/31

27. QD10BFF QD10AFF QM16FF QM15FF QM14FF QM13FF QM12FF QM11FF QD4BFF QD4AFF QD2BFF QD2AFF QF9BFF QF9AFF QF5BFF QF5AFF QD8FF QD6FF QD0FF QD10X QD12X QD14X QD16X QD18X QD20X QF7FF SD4FF QF3FF QF1FF SD0FF QF11X QF13X QF15X QF17X QF19X QF21X SF6FF SF5FF SF1FF QF9X B5FF B2FF B1FF QK1X QK2X QK3X QK4X 40 R0 35 30 Irwin Knobs for coarse coupling correction: R = RI R0 25 = + + + H axy bxy H y = cx y dx y 20 skew 0 h h c d H y , y y 0 a b RI = 0 h b d h 15 ( ) cosh = ( ) = ( ) = 2 cos and sin when 0 h ad bc 0 a c ( ) ( ) 2 and sinh when 0 h 10 5 10th ATF2 Project Meeting, June 30 2010 M. Woodley 27/31 0 30 40 50 60 70 80

28. Summary (1) improvements made to both hardware and diagnostics may have cured the anomalous vertical emittance growth at extraction from the Damping Ring that has been observed for many years QM7R replacement BS3X roll DR emittance diagnostics (XSR, SRIF, LW) the new EXT multi-OTR system should improve our ability to measure and correct emittance faster emittance measurement and skew quad optimization possibility of 4D beam-matrix measurement / reconstruction / correction Flight Simulator dispersion measurement / correction software seems to work excellent improvements in BPM resolution and reliability make it possible propagation of dispersion fits to wire scanners, IP, PIP, etc. correction of FD-phase y with sum-knob model-based xcorrection with QF1X/QF6X sometimes has trouble, but manual correction works jitter-based (SVD) dispersion measurement / monitoring still a possibility 10th ATF2 Project Meeting, June 30 2010 M. Woodley 28/31

29. Summary (2) Flight Simulator Irwin knobs provide possibility of orthogonal manual - matching QM*FF only FF / FD magnets can remain at design strengths orthogonal waist and control orthogonal phase control intriguing possibilities (verticaldispersion, feedback, ) control of IP x-y and x'-y coupling may also be possible 10th ATF2 Project Meeting, June 30 2010 M. Woodley 29/31

30. Ongoing Work (1) need to archive future EXT multi-wire and multi-OTR emittance measurements raw beam sizes, raw dispersion data, wire-to-wire and IEX to MW0X R-matrices analysis results (with errors) coupling measurement / 4D beam reconstruction acquire full data set (X/Y/U/+10/-10) plus raw data files for all EXT wires cross-check raw data normalization and who s who is everything OK now? acquire OTR beam images for all EXT OTRs and extract lengths of semi-major and semi- minor axes and ellipse tilt angles try 4D reconstruction Ilya Agapov s Cholesky decomposition method? consistency checks for emittance and Twiss forward propagate from EXT backward propagate from IP Flight Simulator computer control of Damping Ring RF frequency ramp 10th ATF2 Project Meeting, June 30 2010 M. Woodley 30/31

31. Ongoing Work (2) find a better coarse IP-phase y knob closed bump in FF matching quadrupole region? generate in Damping Ring? is there a way to use the Kubo bump to control IP-phase vertical dispersion? Flight Simulator Irwin knob development GUI FF optics with all QM*FF ON at reasonable currents coupling knobs revisit SLAC epoxy kicker multipoles (if we don t switch to fast stripline extraction permanently) are observed EXT BMAG values consistent? why are vertical bumps at KEX1 closed? are the kickers identical? is there a way to use the Kubo bump to control IP-phase vertical dispersion? and on and on 10th ATF2 Project Meeting, June 30 2010 M. Woodley 31/31