A Transverse Profile Imager for SwissFEL Rasmus Ischebeck

Transcription

1 P AUL SCHERRER INSTITUT observer 12 1 scnitillating crystal s virtual image Emittance [nm] 8 6 d 4 2 primary beam t [ps] A Transverse Profile Imager for SwissFEL

2 Transverse Profile Monitors University of Illinois 2

3 Profile Measurement in FELs 3.5 x y / mm x / mm 3

4 Profile Measurement in FELs 3.5 x y / mm x / mm 3

5 x-y Correlations > Intrinsic correlation y / mm x / mm.8 1 > Explicit x-y dependency introduced by RF deflector 4

6 2-Dimensional Profile Monitors > Optical transition radiation (OTR) > Scintillation 5

7 Imaging Scintillators a) b) c) d) e)

8 Electron Beam Profile Monitors Scintillators, OTR Screens & Wire Scanners Alignment hole and calibration scale Wire scanner Installed scintillators Ce:YAG 5 µm 2 µm 2 µm Fluorescent crystal (Ce:LuAG) Ce:LuAG 2 µm OTR screen (Al-coated Si wafer) RF shield High Energy Screen Low Energy Screen F. Piffaretti

9 Electron Beam Profile Monitors Scintillators, OTR Screens & Wire Scanners Alignment hole and calibration scale Wire scanner Installed scintillators Ce:YAG 5 µm 2 µm 2 µm Fluorescent crystal (Ce:LuAG) Ce:LuAG 2 µm OTR screen (Al-coated Si wafer) RF shield High Energy Screen Low Energy Screen F. Piffaretti

10 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 Projected pixel size: 23 µm 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

11 Scheimpflug Snell Screen Monitor > Theodor Scheimpflug ( ) > Willebrord Snellius ( ) 9

12 Imaging Scintillating Crystals observer s scnitillating crystal virtual image d primary beam 1

13 Imaging Scintillating Crystals s C B scnitillating crystal l d A primary beam 11

14 Imaging Scintillating Crystals observer s scnitillating crystal virtual image d primary beam 12

15 Imaging Scintillating Crystals ideal observation angle scintillating crystal virtual image aligned with beam axis d primary beam 13

16 Trigonometry 14

17 Observed Beam Size 4 35 apparent transverse size s / µm observation angle β / degrees 15

18 Ideal Observation Angle a) b) 16

19 Screen Monitor 17

20 Measurements with the Prototype > Emittance Measurement normalized xp x normalized x x 1 5 normalized yp x normalized y x sigma x [mm].15.1 sigma y [mm] measurement index measurement index Pull x 2 Pull y 5 The smallest beam in this measurement is 5 µm rms. Beams of 1 µm rms have been measured measurement index measurement index 18

21 Measurements with the Prototype > Slice emittance measurement of a 1 pc beam 12 1 Emittance [nm] t [ps] Eduard Prat, Marta Divall 19

22 Measurements with the Prototype > Slice emittance measurement of a 1.3 pc beam 3 Core slice emittance / nm Charge / pc Eduard Prat, Marta Divall 2

23 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 the slide on the Schwarzschild imaging > 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 21