1. A Transverse Profile Imager for SwissFEL Rasmus Ischebeck

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

3. Rasmus Ischebeck Transverse Profile Monitors 3 3 University of Illinois

4. Rasmus Ischebeck Profile Measurement in FELs 4 4

5. Rasmus Ischebeck Coherent OTR 5 5 Joe Frisch

6. Rasmus Ischebeck Coherent OTR 6 6 Joe Frisch

7. Rasmus Ischebeck Profile Measurement in FELs 7 7

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

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

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

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

12. Rasmus Ischebeck Imaging Scintillators 12

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

14. Electron Beam Profile Monitors Visual 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

15. Rasmus Ischebeck Design Considerations >Scheimpflug imaging principle >Snell’s law of refraction 15 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.

16. Rasmus Ischebeck Imaging Scintillating Crystals 16

17. Rasmus Ischebeck Imaging Scintillating Crystals 17

18. Rasmus Ischebeck Imaging Scintillating Crystals 18

19. Rasmus Ischebeck Imaging Scintillating Crystals 19

20. Rasmus Ischebeck Trigonometry… 20

21. Rasmus Ischebeck Observed Beam Size 21

22. Rasmus Ischebeck Ideal Observation Angle 22

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

24. Rasmus Ischebeck Observation Geometry for Scintillator and OTR 24

25. Rasmus Ischebeck Observation Geometry for Scintillator and OTR 25

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

27. Rasmus Ischebeck Screen Monitor 27

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

29. Rasmus Ischebeck Quadrupole Scan 29

30. Rasmus Ischebeck Beam Transmitted Through Slit 30

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

32. Rasmus Ischebeck Slice Emittance Measurement 32 Eduard Prat

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

34. Rasmus Ischebeck 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 34

35. Rasmus Ischebeck 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 35

36. Rasmus Ischebeck