1. Nuruzzaman (http://www.jlab.org/~nur/) Hampton University Group Meeting 1 st November 2011 Beamline Optics Using Beam Modulation for the Q-weak Experiment

2. Overview Basics Hardware for beam modulation Controls and software Data analysis Optics stability during RUN-I 2

3. 3 The objective of the Q p weak experiment is to measure the parity violating asymmetry (~250ppb) in elastic electron-proton(e-p) scattering to determine the proton's weak charge with an uncertainty of 4%.[1] [1] http://www.jlab.org/qweak/ A PV = σ + - σ - _______ σ + + σ - The e-p scattering asymmetry depends on the five beam parameters: horizontal position (X), horizontal angle (X΄), vertical position (Y), vertical angle (Y΄) and energy (E). A measured = A 0 + ∂A ∂T i ∆T i ∑ i T i = X, X´, Y, Y´ & E ∂T i ∂A = detector sensitivity The goal of the Injector group is to keep these helicity-correlated parameters as small as possible. The goal of our beam modulation group is to measure the detector sensitivities to correct remaining false asymmetry.

4. 4 2.5% on A PV  4% on Q weak 0.3% on sin 2 θ W Uncertainty δA PV /A PV δQ w /Q w Statistical (~2.5K hours at 150 μA) 2.1% 3.2% Systematic: 2.6% Hadronic structure uncertainties --- 1.5% Beam polarimetry 1.0% 1.5% Effective Q 2 determination 0.5% 1.0% Backgrounds 0.5% 0.7% Helicity-correlated beam properties 0.5% 0.7% Total: 2.5% 4.1%

5. 1 st Coil2 nd Coil Dipole 3C05 Dipole 3C06 Dipole 3C07 5 Hall C Beamline Zoomed In Target z x / y θ1θ1 θ2θ2 θ1θ1 II I I Z=0 Z=d 1 Z=d 2 Where Ref: http://www-bdnew.fnal.gov/pbar/organizationalchart/lebedev/OptiM/optim.htm http://www-bdnew.fnal.gov/pbar/organizationalchart/lebedev/OptiM/optim.htm

6. 6 Beam Parameter Modulation Amplitude Current through 1 st Coil I 1 (A) Field Integrals for 1 st Coil BdL 1 (G-cm) Current through 2 nd Coil I 2 (A) Field Integrals for 2 nd Coil BdL 2 (G-cm) Tune Parameters (BdL 2 / BdL 1 ) X159 μm 0.088 29.0-0.300-99.0-3.414 X΄3.1 μrad 0.052 17.0-0.300-99.0-5.824 Y84 μm -0.300 -99.00.13645.0-2.200 Y΄2.1 μrad -0.300 -99.00.15049.5-2.000

7. 7 Beam Position Monitor Modulation Coil Pair Hall-C Injector Accelerator 1 st Pair of Coils 2 nd Pair of Coils

8. A B C

9. 9 35 cm Liquid Hydrogen Target Primary Collimator with 8 openings Drift Chambers Toroidal Magnet Drift Chambers Elastically Scattered Electron Eight Fused Silica (quartz) Čerenkov Detectors - Integrating Mode Luminosity Monitors ~3.2 m

10. Beamline Coils X1X1 Y1Y1 Y2Y2 X2X2 SRF E BSY Service Building BMOD1BMOD1 X1X1 X1X1 Y1Y1 Y1Y1 X2X2 X2X2 Y2Y2 Y2Y2 LEM Current Transducer X1X1 Y1Y1 Y2Y2 X2X2 TRIM-I Power Amp. BPMs BMOD2BMOD2 Hall-C GUI CONSOLE Q p weak PV Daq. Q p weak Cage I O C hCnmrhCnmr TRIUMF ADC JLAB ADC 10

11. Bench Test and Results VME Signal Generator IOC 11 We choose frequency 125 Hz to be in linear region

12. 12 X X´ Y Y´ E

13. Phase FGX1 [V] FGX2 [V] BPMX [mm] BPMY [mm] Target BPM Response to X Modulation 13

14. Run 11116: Hall-C BPM X Response to X Modulation 14

15. Run 11116: Hall-C BPM X Response to X Modulation 15

16. Run 11116: Hall-C BPM Y Response to Y Modulation 16

17. Run 11116: Hall-C BPM X Response to E Modulation 17

18. Run 11116: BPM Response to X Modulation 18

19. General Information Run conditions: Production running Beam current: 150 -180 µA Modulation with pair of coils Modulation frequency: 125 Hz Three modulation tunes (I 2 /I 1 ) : I, IIA, IIB This presentation includes: Time span: 14 th February – 13 th May 2011 Run range covered: 10,046 – 12,120 Mps_Tree 19

20. Non-zero X-Y coupling at target become obvious here BPM Response to X Modulation During RUN-I Small drifts in X ! BMod Position Amplitude [mm] 20

21. 21 BPM Response to X Modulation During RUN-I Wien 1Wien 2Wien 3Wien 4Wien 5 Are these fluctuations due to FG drive signals ?

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23. 23 X-Y Correlation for X Modulation During RUN-I Hypothesis: Sick quadrupole downstream of 3C12 Problem in X tgt, Y tgt amplitude

24. Y tgt is relatively unstable for Y modulation: Designed that way BPM Response to Y Modulation During RUN-I BMod Position Amplitude [mm] 24

25. 25 BPM Response for Y Modulation During RUN-I Wien 1Wien 2Wien 3Wien 4Wien 5

26. 26 X-Y Correlation to Y Modulation During RUN-I

27. Y tgt (≥X tgt ) has ~ 1/7 th dispersion of 3C12X BPM Response to E Modulation During RUN-I BMod Position Amplitude [mm] Residual dispersion coming from upstream BMod Position Amplitude [mm] Run 11116: Hall-C BPM Y Response to E Modulation 27

28. 28 BPM Response to E Modulation During RUN-I Wien 1Wien 2Wien 3Wien 4Wien 5

29. 29 X-Y Correlation for E Modulation During RUN-I

30. Summary Coil positioning has been defined by using OPTIM, and hardware has been installed. We did bench test with modulation hardware before installation. Hardware and software worked fine during RUN-I period. Analyzing data from RUN-I ……. X modulation: X tgt and Y tgt are relatively unstable, has slow drifts and glitches. Sick quad, problems with X tgt and Y tgt amplitude ? Co-related X-Y coupling. BPM 3C12 X and Y responses are relatively stable. 30

31. Summary Y modulation: Y tgt response is significantly unstable. Designed that way (tune parameters for Y and Y´ are close). X tgt, BPM 3C12 X and Y responses are relatively stable. No obvious X-Y coupling. E modulation: Non zero X tgt & Y tgt motion. Residual dispersion coming from upstream of BPM 3C07A ! To Do Track down reasons for outliers. Discuss with MCC to reliably reduce the residual dispersion at target (It may help Compton background). 31

32. References Other Optics Related Changes 02/17/11 Injector transmission problem, beam steering: ELOG 1568849ELOG 1568849 04/13/11 Raised Hall-C laser GSET: ELOG 1579174ELOG 1579174 04/14/11 Hall-C laser phase adjustment: ELOG 1579218ELOG 1579218 04/22/11 Moller quad adjustment: ELOG 1583168ELOG 1583168 04/23/11 Optics change: ELOG 1587140ELOG 1587140 05/02/11 2L06-1 common fault dropped to idle: ELOG 1625072ELOG 1625072 05/02/11 30hz synchronization errors: ELOG 1625050 ELOG 1625050 05/04/11 Hall-C Moller quads cycled: ELOG 1627033ELOG 1627033 05/05/11 Hall-C Moller quads are on: ELOG 1627277ELOG 1627277 Injector Spot Moved 02/14/11: ELOG 156833704/20/11:ELOG 1580368ELOG 1568337ELOG 1580368 02/25/11:ELOG 157088604/25/11:ELOG 1596408ELOG 1570886ELOG 1596408 03/01/11:ELOG 157202604/29/11:ELOG 1613315ELOG 1572026ELOG 1613315 03/24/11:ELOG 157631005/03/11: ELOG 1626740ELOG 1576310ELOG 1626740 04/03/11:ELOG 157747805/10/11: ELOG 1628317ELOG 1577478ELOG 1628317 04/07/11:ELOG 1578273ELOG 1578273 QTOR Corrector Magnet Q-weak QTOR ELOG

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35. BPM3C12 Target BPM Run 11116: Hall-C BPM X Response to X Modulation 35

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39. Hint of correlation X-Y Correlation to X Modulation During RUN-I BMod Y Target Position Amplitude [mm] BMod X Target Position Amplitude [mm] 39

40. X-Y Correlation to Y Modulation During RUN-I BMod Y Target Position Amplitude [mm] BMod X Target Position Amplitude [mm] 40

41. X-Y Correlation to E Modulation During RUN-I BMod Y Target Position Amplitude [mm] BMod X Target Position Amplitude [mm] 41

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51. 51 Run 11116: Hall-C BPM Y Response to Y Modulation

52. 52 Run 11116: Hall-C BPM X Response to E Modulation

53. 53 Run 11116: Hall-C BPM X Response to X Angle Modulation

54. 54 Run 11116: Hall-C BPM Y Response to Y Angle Modulation

55. Linked Slide 55

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57. 57 Unstable beam vacuum problem

58. 58 Large charge asymmetry & BPM differences

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68. 68 Unstable beam vacuum problem Feedback test

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78. 78 Orbit lock moved Beam profile scan Compton lock might be incorrect Unstable beam QTOR failure & MCC valve problem

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82. X-Y Correlation to Modulation During RUN-I BMod Y Target Position Amplitude [mm] BMod X Target Position Amplitude [mm] 82

83. (at tree level) Q p Weak : extract from Parity-Violating Electron Scattering measures Q p – proton’s electric charge measures Q p Weak – proton’s weak charge M EM M NC (as Q 2  0 ) Correction involves hadron form factors. Determine using global analysis of recently completed PVES experiments. The lower the momentum transfer, Q, the more the proton looks point-like; form factor corrections get less important. “accidental” suppression of Q w p enhances sensitivity to new physics 83

84. 84 SM curve by: J. Erler, M. Ramsey-Musolf and P. Langacker Qweak decreasing Qweak increasing Running of sin 2 θ W Q [GeV]