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A Transverse Profile Imager for SwissFEL Rasmus Ischebeck

A Transverse Profile Imager for SwissFEL Rasmus Ischebeck. A Transverse Profile Imager for SwissFEL. Profile measurement in FELs Imaging scintillating crystals Applications. Rasmus Ischebeck. 2. Transverse Profile Monitors. University of Illinois. Rasmus Ischebeck. 3.

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A Transverse Profile Imager for SwissFEL Rasmus Ischebeck

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  1. A Transverse Profile Imager for SwissFELRasmus Ischebeck

  2. A Transverse Profile Imager for SwissFEL • Profile measurement in FELs • Imaging scintillating crystals • Applications Rasmus Ischebeck 2

  3. Transverse Profile Monitors University of Illinois Rasmus Ischebeck 3

  4. Profile Measurement in FELs Rasmus Ischebeck 4

  5. Coherent OTR Joe Frisch Rasmus Ischebeck 5

  6. Coherent OTR Joe Frisch Rasmus Ischebeck 6

  7. 1-Dimensional Profile Monitor Gian Luca Orlandi, Prajwal Mohanmurthy Rasmus Ischebeck 8

  8. x-y Correlations • Intrinsic correlation • Explicit x-y dependency introduced by RF deflector Rasmus Ischebeck 9

  9. A Transverse Profile Imager for SwissFEL • Profile measurement in FELs • Imaging scintillating crystals • Applications Rasmus Ischebeck 10

  10. 2-Dimensional Profile Monitors • Optical transition radiation (OTR) • Scintillation Rasmus Ischebeck 11

  11. Imaging Scintillators Rasmus Ischebeck 12

  12. Electron Beam Profile MonitorsScintillators, OTR Screens & Wire Scanners • Installed scintillators • Ce:YAG • 5 µm • 20 µm • 200 µm • Ce:LuAG • 200 µm 13 Rasmus Ischebeck – Scintillators for SwissFEL

  13. Electron Beam Profile MonitorsVisual Light Optics • OTR screen / scintillator is at an angle of 45º to the optical axis • For overview camera (1:5.3 demagnification) • Use Scheimpflug criterion to correct image plane orientation • For 1:1 imaging • Perspective control lens is not available commercially • Only central part (~1…2 mm) of the screen can be imaged within depth of field 14 Rasmus Ischebeck – Scintillators for SwissFEL

  14. Design Considerations • Scheimpflug imaging principle • Snell’s law of refraction Observation of the Scheimpflug imaging principle allows to image the entire screen without depth- of-field issues. To avoid astigmatism, the lens is not tilted, but the detector is tilted. For a 1:1 imaging, we tilt the CMOS sensor by 15º. The YAG / LuAG scintillators are observed at such an angle that Snell’s law of refraction is observed. As a consequence, we can image beams that are smaller than the thickness of the scintillator. Rasmus Ischebeck 15

  15. Imaging Scintillating Crystals Rasmus Ischebeck 16

  16. Imaging Scintillating Crystals Rasmus Ischebeck 17

  17. Imaging Scintillating Crystals Rasmus Ischebeck 18

  18. Imaging Scintillating Crystals Rasmus Ischebeck 19

  19. Trigonometry… Rasmus Ischebeck 20

  20. Observed Beam Size Rasmus Ischebeck 21

  21. Ideal Observation Angle Rasmus Ischebeck 22

  22. Measurement Principle • Combination of two monitors: • Scintillating crystal • Optical transition radiation Rasmus Ischebeck 23

  23. Implementation (coherent) OTR to camera Rasmus Ischebeck 26

  24. Screen Monitor Rasmus Ischebeck 27

  25. A Transverse Profile Imager for SwissFEL • Profile measurement in FELs • Imaging scintillating crystals • Applications Rasmus Ischebeck 28

  26. Quadrupole Scan Rasmus Ischebeck 29

  27. Beam Transmitted Through Slit Rasmus Ischebeck 30

  28. Slice Emittance Measurements Measurement performed by Eduard Prat & Marta Divall • Slice emittance measurement of a 1.3 pC beam 200 µm Rasmus Ischebeck 31

  29. Slice Emittance Measurement Eduard Prat Rasmus Ischebeck 32

  30. Slice Emittance Measurements Measurements performed by Eduard Prat & Marta Divall • Core slice emittance as a function of charge Rasmus Ischebeck 33

  31. A Transverse Profile Imager for SwissFEL • A transverse profile imager that considers • Snell’s law of refraction in the scintillating crystal • The Scheimpflug imaging condition • Prototype installed at the SwissFEL Injector Test Facility • Resolution measured with this prototype: σ ≲ 10 µm, ε ≲ 30 nm • Sensitivity: Q ≲ 1 pC • Next Plans • Prove immunity to coherent OTR • Start series production Rasmus Ischebeck 34

  32. Thank You to… • Hansueli for the technical design • The AMI team for manufacturing the components • Markus for the assembly • Markus, Albert & the vacuum group for installation • Eduard the emittance measurement software, and for using the new profile monitor extensively for emittance measurements • Gian Luca, Marta, Simona, Carlo, Thomas & Eduard for the measurements presented in this talk • Vincent for help with optical design • Andrea for support with patenting the design, and with connections to industry • Helge for camera server software, and Babak for synchronized data acquisition • The entire Commissioning and Operations crew Rasmus Ischebeck 35

  33. Rasmus Ischebeck

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