1. 1 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 1 BFW Results June 2009 FAC BFW Results Heinz-Dieter Nuhn – LCLS Undulator Group Leader June 9, 2009

2. 2 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 2 BFW Results June 2009 FAC LCLS Undulator Components Quadrupole BPM Manual Adjustments Segment Cam Shaft Movers WPM HLS BFW Sand-Filled, Thermally Isolated Fixed Supports Horizontal Slides Not visible Vacuum Chamber and Support

3. 3 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 3 BFW Results June 2009 FAC Beam Finder Wire Location on Girder Beam Finder Wire Housing Beam Direction Undulator Segment Vacuum Chamber

4. 4 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 4 BFW Results June 2009 FAC BFW Assembly (Body Sectioned) Wire card (Down Position) (Inactive Mode) Lower Limit Switch (Actuated Position) Pneumatic Solenoid Valve (Cylinder Vent Position) Internal Return Spring (Expanded Position) Electrical Connectors (Down Position) Internal Kinematic Stop Plates (Open Position) Bellows Seal (Compressed Position) BEAM Potentiometer (Out Position) Assembly model courtesy: J. Bailey, ANL

5. 5 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 5 BFW Results June 2009 FAC BFW Card Material: Macor Thickness: 3/16” (4.8 mm) Coating: Kovar Full Stroke: 25.4 mm X-wire end point: 39.614 mm Beam center: 40 mm Gap between beam and X-wire: 0.386 mm Y-wire end point: 37.014 mm Beam center: 37.2 mm Gap between beam and Y-wire: 0.186 mm Beam in OUT Position Beam in IN Position Beam travels out of slide plane

6. 6 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 6 BFW Results June 2009 FAC BFW Card Wiring: Tooling Copper Tabs Rods for hanging BFW wire with weights Micrometer stage BFW Card Card holder ‘Carbon wire & weight’ Wires soldered to copper tabs Wires from copper tabs connect to BFW feedthrough Feedthrough to be grounded and RF shielded Courtesy: C. Field, Y.Sung

7. 7 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 7 BFW Results June 2009 FAC BFW Wires X-Wire Y-Wire Nominal Beam Axis in IN Position Card Out Direction (½ stroke length shown) Wire Radius 34 - 40 µm Note: Wires are fixed! Beam scanning will be achieved through girder motion.

8. 8 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 8 BFW Results June 2009 FAC BFW Functions Beam Direction A misaligned undulator will not steer the beam. It will just radiate at the wrong wavelength. The BFW allows the misalignment to be detected. (also allows beam size measurements) UndulatorQuadBFW Replacement Vacuum Chamber Wires BFW Planned Applications Loose End Alignment Beam Profile Scanning Planned Applications Loose End Alignment Beam Profile Scanning Girder

9. 9 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 9 BFW Results June 2009 FAC Location of BFW Detectors 40 Detectors are used for BFW readout 33 PEP-II style radiator/PMT units: one after each BFW device 5 ANL Beam loss monitors: next to PEP-II devices on girders 1, 9, 17, 25, 33. 2 Beam loss fibers: BLF U01-U16 covering upstream girder, BLFU 17-U33 covering downstream girders Wire charge diagnostics is not installed

10. 10 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 10 BFW Results June 2009 FAC Scan Procedure Incorporated in Matlab GUI Start matlab gui BFWscan_gui Choose girders (1-33), X-wire or Y-wire, scan range, and scan step size For instance Girder: 1 - 33 Wire: ‘X’ and ‘Y’ Range: -250 microns to +250 microns Step size: 50 microns. When started, the gui will then for each selected girder Move the girder cams to place the upstream girder end to the beginning of the scan range relative to the estimated collision point. (Motion is pivoted at the quadrupole) Move the wire card to “IN” position (while beam stopper is inserted) Take measurements from the 8 detectors, add the results to the graphs and go on to the next location. When done, return the girder to the position at which it was started. Move the wire card to “OUT” position. Move the girder back to its standard location. The gui will stop the beam upstream of the undulator line during wire card insertion/extraction and during motion to the next position.

11. 11 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 11 BFW Results June 2009 FAC Scan with BFW11 Y-Wire Dump CerenkovDump Scintillator ANL BLM 25 Expected Collision Position BLF:U17-U33BLF:U01-U16 PEP-II BLM25 PEP-II BLM17 ANL BLM 33

12. 12 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 12 BFW Results June 2009 FAC BFW Alignment before FEL Commissioning

13. 13 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 13 BFW Results June 2009 FAC BFW Alignment after FEL Commissioning

14. 14 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 14 BFW Results June 2009 FAC DMP Cerenkov Detector Amplitudes Noise levels is due to coarse step size of 50 microns. 20 microns steps ize scans are planned for the near future.

15. 15 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 15 BFW Results June 2009 FAC Transverse Electron Beam Sizes

16. 16 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 16 BFW Results June 2009 FAC ANL/PEP Loss Monitor Responses

17. 17 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 17 BFW Results June 2009 FAC BLF 17-33 Responses Girder Range Covered by Fiber

18. 18 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 18 BFW Results June 2009 FAC FEL Scattering on BFW wire Fringes indicate transverse coherence

19. 19 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 19 BFW Results June 2009 FAC The 33 Beam Finder Wire (BFW) devices in the undulator system are working very well. They enable monitoring of several parameters Loose-end alignment Beam sizes, i.e. betatron matching BLM calibration Transverse FEL coherence. Radiation levels produced by the scans are much lower than originally estimated allowing unrestricted use. Use has so far been restricted to higher electron beam energies due to the possibility of wire damage when interacting with the lowest energy FEL beam. The 33 Beam Finder Wire (BFW) devices in the undulator system are working very well. They enable monitoring of several parameters Loose-end alignment Beam sizes, i.e. betatron matching BLM calibration Transverse FEL coherence. Radiation levels produced by the scans are much lower than originally estimated allowing unrestricted use. Use has so far been restricted to higher electron beam energies due to the possibility of wire damage when interacting with the lowest energy FEL beam. Summary

20. 20 Heinz-Dieter Nuhn nuhn@slac.stanford.edu 20 BFW Results June 2009 FAC End of Presentation