1. 1 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 1 Undulator Commissioning August 2009 FEL2009 Undulator Commissioning, Alignment and Performance Heinz-Dieter Nuhn – LCLS Undulator Group Leader August 27, 2009

2. 2 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 2 Undulator Commissioning August 2009 FEL2009 All 33 Undulator Segments Operational

3. 3 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 3 Undulator Commissioning August 2009 FEL2009 Girder Components Quadrupole and horz/vert Correctors BFW Undulator Segment Girder Segment Slider Girder Mover (cam) RF Cavity BPM HLS Sensor Part of WPM Support

4. 4 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 4 Undulator Commissioning August 2009 FEL2009 Undulator Beam Operation Highlights December 13, 2008 First electron beam through undulator vacuum chamber without undulator segments. No extra steering corrections necessary to get 100% transmission to main dump. Pre-beam girder alignment was sufficient. April 10, 2009 First electron beam through undulator segments. Detected FEL beam after 105 minutes, CCD saturation 20 minutes later. December 13, 2008 First electron beam through undulator vacuum chamber without undulator segments. No extra steering corrections necessary to get 100% transmission to main dump. Pre-beam girder alignment was sufficient. April 10, 2009 First electron beam through undulator segments. Detected FEL beam after 105 minutes, CCD saturation 20 minutes later.

5. 5 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 5 Undulator Commissioning August 2009 FEL2009 Preparation for First Electron Beam Extensive pre-beam checkout procedure Precise girder alignment mapping (error ellipse about 50 µm) Quadrupole position adjustment to remove residual deviations from straight line as reported by last alignment mapping data. to add offsets to compensate for the environmental fields (earth magnetic field etc.) as measured with field probe (five points per girder). Extensive pre-beam checkout procedure Precise girder alignment mapping (error ellipse about 50 µm) Quadrupole position adjustment to remove residual deviations from straight line as reported by last alignment mapping data. to add offsets to compensate for the environmental fields (earth magnetic field etc.) as measured with field probe (five points per girder).

6. 6 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 6 Undulator Commissioning August 2009 FEL2009 Mount and precision-align Undulator, Quad, BPM and BFW on girder Align girders using conventional alignment to bring quadrupole centers onto straight line to 50 μm rms. Beam straightness requirement through undulator: 2 μm rms per field gain length (about 7 m) => Use Beam Based Alignment (BBA) with set of different energies for final quadrupole alignment Use BFW scans for upstream alignment. Mount and precision-align Undulator, Quad, BPM and BFW on girder Align girders using conventional alignment to bring quadrupole centers onto straight line to 50 μm rms. Beam straightness requirement through undulator: 2 μm rms per field gain length (about 7 m) => Use Beam Based Alignment (BBA) with set of different energies for final quadrupole alignment Use BFW scans for upstream alignment. Undulator Line Alignment Overview Beam Undulator Segment Quad/Corr RFBPM Res < 1 μm Conventional Girder Alignment Grossly out of scale for clarity BFW After BBA: all Quads aligned Wire inserted (One at a time) After BFW scan/align Wires extracted Ready for FEL

7. 7 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 7 Undulator Commissioning August 2009 FEL2009 Beam Finder Wire Electron Scattering Xray Scattering

8. 8 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 8 Undulator Commissioning August 2009 FEL2009 Beam Based Alignment Principle BPM offsets unknown Magnetic fields (earth, quad kicks, etc.) unknown Task: Correct field integrals using quad offsets or correctors for dispersion free trajectory at BPM positions Trajectory between BPMs remains unknown Measure trajectory at different energies to extrapolate to straight line at infinite energy Keep undulator quadrupole fields fixed BPM position is BPM offset at infinite energy BPM offsets unknown Magnetic fields (earth, quad kicks, etc.) unknown Task: Correct field integrals using quad offsets or correctors for dispersion free trajectory at BPM positions Trajectory between BPMs remains unknown Measure trajectory at different energies to extrapolate to straight line at infinite energy Keep undulator quadrupole fields fixed BPM position is BPM offset at infinite energy The following pages Illustrate the BBA Concept as implemented by Henrik Loos for the LCLS

9. 9 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 9 Undulator Commissioning August 2009 FEL2009 Launch Parameters LE1, …, LE4 (Position & Angle; Energy dependent) BBA Measurement Schematic Δq1Δq1 Δq3Δq3 Δq2Δq2 Δb1Δb1 Δb3Δb3 Δb2Δb2 Δy1Δy1 Δy3Δy3 Δy2Δy2 Δy0Δy0 Δy4Δy4 Δb4Δb4 Δb0Δb0 E1E1 E2E2 BPM Readings LE1 E1 < E2E1 < E2 y = M x Solve Equations LE2 Measure (y) Obtain Results (x) Positions not observable BPM Reading (each for h, v, and E) @ 4 Energies yjyj Quad Offsets Δq j (each for h and v) BPM Offsets Δb i (each for h and v)

10. 10 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 10 Undulator Commissioning August 2009 FEL2009 BBA M Matrix = Y M X YHYH YVYV XHXH XVXV MHMH MVMV 0 0 = × × YH150 × 1 XH78 × 1 Y300 × 1 X156 × 1 M300 × 156

11. 11 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 11 Undulator Commissioning August 2009 FEL2009 BBA Horizontal M Matrix XLXL 2 × 1 MLML 37 × 2 C1C1 1 × 33 C2C2 = YHYH MHMH XHXH Y HE1 X  Q,H = X  B,H Y HE2 Y HE3 Y HE4 X LHE1 M QHE1 M QHE2 M QHE3 M QHE4 MBMB MBMB MBMB MBMB M LHE1 M LHE2 M LHE3 M LHE4 X LHE2 X LHE3 X LHE4 × × Dimensions MBMB 37 × 37 MQMQ 37 × 33 YHYH 150 × 1 XHXH 78 × 1 MHMH 150 × 78 C2C2 C1C1

12. 12 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 12 Undulator Commissioning August 2009 FEL2009 BBA Horizontal M Sub-Matrices and Vectors 37 × 37 37 × 33 37 × 2 if 0therwise 1 × 33 1 × 2 BPM Offset Matrix Launch Position Vector Launch Trajectory Matrix Constraint Vector =0 Constraint Vector Quad Mover Matrix

13. 13 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 13 Undulator Commissioning August 2009 FEL2009 BBA Implementation Setup accelerator for one energy Calculate response matrix for this energy Measure N trajectories at this energy and average Repeat for all energies Generate M-matrix with energy dependent elements and selected constraints Add constraint equations for quad or BPM offsets 0 = Σ i Δq i and 0=Σ i z i Δq i for linear quad offset constraint 0 = Δq i for minimum quad offset constraint Fit quad and BPM offsets and implement Repeat BBA procedure Fit solution for Δy arbitrary to adding linear function to quad and BPM offsets

14. 14 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 14 Undulator Commissioning August 2009 FEL2009 BBA Result Measured Trajectories 4 th Iteration Position rms 2 – 6 μm

15. 15 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 15 Undulator Commissioning August 2009 FEL2009 BBA Results Fit with Linear Quad Constraint Offset Error Bar 10 μm

16. 16 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 16 Undulator Commissioning August 2009 FEL2009 Quad Position/Kick Comparison Quadrupole positions relative to the electron beam measured by changing the quadrupole gradient and fitting the kick angle. Kick angles are converted to field integrals between quads. As reference undulator segment first field integral tolerance is ±40 µTm. Fitted 1 st Field Integrals Undulator 1 st Field Integral Tolerance: ±40 µTm Measured Quad Center Displacement to BBA Beam

17. 17 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 17 Undulator Commissioning August 2009 FEL2009 Estimated Result of “Quad BBA” Estimate of the trajectory if instead of energy-dependent BBA the quadrupoles would have been moved to center them on the beam. The resulting trajectory is not dissimilar to the one we use to suppress FEL lasing. This illustrates the need for energy-dependent BBA!

18. 18 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 18 Undulator Commissioning August 2009 FEL2009 Girder Stability : Position / Temperature Girder component motion and undulator temperature variation change the electron beam trajectory (phase errors) due to changing quadrupole offsets the undulator strength, which depends on temperature beam trajectory Good News: Observed stability of quad positions and undulator temperatures is better than expected. Girder component motion and undulator temperature variation change the electron beam trajectory (phase errors) due to changing quadrupole offsets the undulator strength, which depends on temperature beam trajectory Good News: Observed stability of quad positions and undulator temperatures is better than expected.

19. 19 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 19 Undulator Commissioning August 2009 FEL2009 QU05 Stability Over 68-Hour Period Alignment Diagnostics System (ADS) 1 µm 24 hours Alignment Diagnostics System (ADS) 1 µm 24 hours Horizontal Quad Position Vertical Quad Position The ADS is based on (1) two 140-m-long stretched wires carrying a 140 MHz RF signal observed by four wire position monitors (WPMs) per girder and (2) a global water level system (HLS), also with four monitors per girder. The system has a 100 nm resolution. The combined information from both subsystems is processed and continuously recorded. The graph shows, as an example, the recording of a 68-hour period during which no girder or segment was moved. The ADS is based on (1) two 140-m-long stretched wires carrying a 140 MHz RF signal observed by four wire position monitors (WPMs) per girder and (2) a global water level system (HLS), also with four monitors per girder. The system has a 100 nm resolution. The combined information from both subsystems is processed and continuously recorded. The graph shows, as an example, the recording of a 68-hour period during which no girder or segment was moved. Quad Position Stability Tolerance 1 µm rms

20. 20 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 20 Undulator Commissioning August 2009 FEL2009 U16 Temperature Stability over 15 day Period 50 mK 24 hours Tunnel Lights On Temperatures are monitored with 12 sensors per girder J. Welch presented poster about temperature control on Tuesday: TUPC53

21. 21 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 21 Undulator Commissioning August 2009 FEL2009 Segmented Undulator Pre-Taper

22. 22 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 22 Undulator Commissioning August 2009 FEL2009 Neutral; K=3.4881;  x= 0.0 mm Undulator Roll-Away and K Adjustment First; K=3.5000;  x=-4.0 mmRoll-Away; K=0.0000;  x=+80.0 mm Horizontal Slide Pole Center Line Vacuum Chamber

23. 23 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 23 Undulator Commissioning August 2009 FEL2009 Segmented Undulator K Control K ADJUSTMENT RANGE (MEASURED) TEMPERATURE CORRECTED KACT TAPER REQUEST K ADJUSTMENT RANGE (MEASURED)

24. 24 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 24 Undulator Commissioning August 2009 FEL2009 Checking Undulator K Using YAG Luminescence* 3 rd harmonic of Spontaneous Undulator Radiation on YAG Crystal E e = 11.1 GeV E e = 11.3 GeV E e = 11.5 GeV E e = 11.7 GeV E e = 11.9 GeV Spontaneous Radiation from Dump Bend Yttrium K Edge at 17.038 keV equals 3 rd harmonic of undulator radiation at 11.286 GeV *by J. Welch and J. Frisch K max =3.4256 K min =3.3532 K avg =3.4616 Expected K und = 3.4926±0.0005 More precise bracketing gives K avg =3.4932±0.0045 (1.7 ×10 -4 from expected value) For detailed K measurements see talk by J. Welch in this session: THOA05

25. 25 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 25 Undulator Commissioning August 2009 FEL2009 Undulator Characterization: 1 st Field Integral U09 Beam Based Measurements Horizontal (I1X) and vertical (I1Y) first field integrals measured by fitting a kick to the difference trajectory as function of undulator displacement Reference Point MMF Measurement Requires 20 nm BPM resolution

26. 26 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 26 Undulator Commissioning August 2009 FEL2009 Radiation Control and Monitoring Undulator radiation damage is greatly reduced through Machine Protection System (MPS) interlocks that inhibit beam to the undulator hall when BLM (38 monitors) signals are above threshold Beam loss fiber signals are above threshold Horizontal and/or vertical trajectory is outside ±1mm Comparator toroids indicate beam loss. Any of the upstream profile monitors is inserted More than 1 BFW is inserted or a BFW is moving A regular TLD monitoring program is in place Undulator radiation damage is greatly reduced through Machine Protection System (MPS) interlocks that inhibit beam to the undulator hall when BLM (38 monitors) signals are above threshold Beam loss fiber signals are above threshold Horizontal and/or vertical trajectory is outside ±1mm Comparator toroids indicate beam loss. Any of the upstream profile monitors is inserted More than 1 BFW is inserted or a BFW is moving A regular TLD monitoring program is in place

27. 27 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 27 Undulator Commissioning August 2009 FEL2009 TLD Readings at First Undulator LOCATIONWEEK 1 PHOTON [rad]WEEK 2 PHOTON [rad]WEEK 3 PHOTON [rad] U25:ANL-BLM0.0810.1060.051 U25: PEP-BLM0.0420.0480.030 U25: Back +X0.0650.0080.033 U25: Back +Y0.0120.0710.064 U25: Back -X0.0390.0260.029 U25: Back +Y0.0130.0420.014 U25: Front +X0.1120.0930.072 U25: Front +Y0.2170.1050.110 U25: Front -X0.0460.0550.025 U25: Front -Y0.1410.1230.093 Recorder Photon Doses about 0.1 rad per week

28. 28 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 28 Undulator Commissioning August 2009 FEL2009 Dose During Initial FEL Operation e-folding length 8.7 m Increased TLD Readings are expected to be predominantly low energy synchrotron radiation, not to cause significant magnet damage [rad]

29. 29 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 29 Undulator Commissioning August 2009 FEL2009 SN20 Radiation Damage Test HAS BEEN INSTALLED ON GIRDER 33 DURING FEL OPERATION NO NOTICABLE CHANGE IN FIELD PROPERTIES DURING 2 MONTH OF FEL OPERATON NO NOTICABLE CHANGE IN FIELD PROPERTIES DURING 2 MONTH OF FEL OPERATON ± 40 µTm Tol ± 50 µTm 2 ± 40 µTm ± 10 ° ± 50 µTm 2 ± 10° ± 15 × 10 -5

30. 30 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 30 Undulator Commissioning August 2009 FEL2009 Alignment Tolerance Verification Random misalignment with flat distribution of widh ± a => rms distribution a/sqrt(3) Beam Based Measurements

31. 31 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 31 Undulator Commissioning August 2009 FEL2009 Beam Based K Tolerance Verification Beam Based Measurements

32. 32 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 32 Undulator Commissioning August 2009 FEL2009 LCLS Undulator Tolerance Budget Error Source ii fifi  i f i Units @ 130 m(24.2% red.) Hor/Ver Optics Mismatch (  -1) 0.5 0.710.4520.32 Hor/Ver Transverse Beam Offset300.1763.7µm Module Detuning  K/K 0.0600.4000.024% Module Offset in x11210.125140µm Module Offset in y2680.29880µm Quadrupole Gradient Error8.80.0290.25% Transverse Quadrupole Offset4.70.2141.0µm Break Length Error20.30.0491.0mm Tolerance Budget Components Module Offset in x @ z SAT 780µm BB Verification 0.06 1200 8.8 770 MEASUREMENTS

33. 33 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 33 Undulator Commissioning August 2009 FEL2009 LCLS undulator system is successfully commissioned. Initial beam operation went extremely smoothly: no tweaking required BBA procedure is successfully implemented Converges to ~1 μm trajectory rms Important to have full energy range (4.30 GeV – 13.64 GeV) BBA complemented by measurement of quad offsets by varying quad strength Temperature and girder stability are well within tolerance Beam loss control and radiation monitoring is in place High radiation levels observed during FEL operation are predominantly low energy photons that are not expected generate demagnetization Very low dose levels measured at electronics components Several undulator tolerances could be verified with beam based measurements LCLS undulator system is successfully commissioned. Initial beam operation went extremely smoothly: no tweaking required BBA procedure is successfully implemented Converges to ~1 μm trajectory rms Important to have full energy range (4.30 GeV – 13.64 GeV) BBA complemented by measurement of quad offsets by varying quad strength Temperature and girder stability are well within tolerance Beam loss control and radiation monitoring is in place High radiation levels observed during FEL operation are predominantly low energy photons that are not expected generate demagnetization Very low dose levels measured at electronics components Several undulator tolerances could be verified with beam based measurements Summary

34. 34 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 34 Undulator Commissioning August 2009 FEL2009 SLAC The dedicated operations, metrology, engineering, controls, installation, and RF groups at SLAC ANL The tremendous ANL undulator and BPM team The extraordinary commissioning team John Galayda (project director) for his leadership And many of you, who have contributed your ideas Thanks to…