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AWAKE Electron Spectrometer

AWAKE Electron Spectrometer. Simon Jolly 6 th December 2013. Spectrometer Specifications. Wakefield accelerated electrons ejected collinear with proton beam: need to separate the 2 and measure energy of electron beam only.

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AWAKE Electron Spectrometer

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  1. AWAKE Electron Spectrometer Simon Jolly 6th December 2013

  2. Spectrometer Specifications • Wakefield accelerated electrons ejected collinear with proton beam: need to separate the 2 and measure energy of electron beam only. • Must be able to resolve energy spread as well as energy: spectrometer must accept a range of energies, probably 0-5 GeV. • Current conceptual layout: • Dipole mounted ~2 m downstream of plasma exit induces dispersion in electron beam. • Scintillator screen 1 m downstream of dipole intercepts electron beam ONLY. • Dispersion gives energy-dependent position spread on screen. • Scintillator imaged by intensified CCD camera viewing upstream face of scintillator screen. Simon Jolly, UCL, AWAKE Collaboration Meeting

  3. 2 GeV Beam, 1.86 T Field Simon Jolly, UCL, AWAKE Collaboration Meeting

  4. 2 GeV Beam, 1.86 T Field Simon Jolly, UCL, AWAKE Collaboration Meeting

  5. 2 GeV Beam, 1.86 T Field Simon Jolly, UCL, AWAKE Collaboration Meeting

  6. 2 GeV Beam, 1.86 T Field Simon Jolly, UCL, AWAKE Collaboration Meeting

  7. 2 GeV Beam, 1.86 T Field Simon Jolly, UCL, AWAKE Collaboration Meeting

  8. 2 GeV Beam, 1.86 T Field Simon Jolly, UCL, AWAKE Collaboration Meeting

  9. AWAKE Spectrometer Area Simon Jolly, UCL, AWAKE Collaboration Meeting

  10. Spectrometer Layout CERN MBPS dipole Camera Electrons + Protons Protons Scintillator Screen

  11. Current Progress • Reconstruction software shows we can resolve energy spread in electron beam given reasonable intensity pattern on screen. • Current work progressing on several fronts: • Scintillator screen light output. • Vacuum layout (protons inside, DAQ outside). • Optimum experimental geometry. • Alternative screen technologies. Simon Jolly, UCL, AWAKE Collaboration Meeting

  12. Scintillator Screen • Default scintillator choice is Lanex: • Manufactured by Kodak. • Used in Medical Physics as X-ray phosphor for imaging. • Gd2O2S:Tb – Gadolinium sensitiser, Terbium dopant activator/wavelength shifter. • Phosphor grains on reflective backing. • Properties don’t seem to be well documented/studied… • Need to simulate light production (photons per MeV conversion efficiency) to ensure we have enough photons emitted in direction of camera. • Is this the correct scintillator for our purposes? • We care about: • Light output. • Resolution • Radiation hardness. • Area. • We don’t care about: • Speed. Simon Jolly, UCL, AWAKE Collaboration Meeting Vac. Chamb. (grey)

  13. GadOx: Geant4 Photons (J. Goodhand) Simon Jolly, UCL, AWAKE Collaboration Meeting

  14. And Now:A Scintillator Interlude. A Scinterlude youtu.be/gaI6kBVyu00 Simon Jolly, UCL, AWAKE Collaboration Meeting

  15. MBPS Magnet Simon Jolly, UCL, AWAKE Collaboration Meeting

  16. MBPS Magnet: Good Field Region? 300 mm 1000 mm Simon Jolly, UCL, AWAKE Collaboration Meeting

  17. Spectrometer Layout Simon Jolly, UCL, AWAKE Collaboration Meeting

  18. Spectrometer + Beam Dump Simon Jolly, UCL, AWAKE Collaboration Meeting

  19. Beam Dump Simon Jolly, UCL, AWAKE Collaboration Meeting

  20. AWAKE Spectrometer Area (1) Simon Jolly, UCL, AWAKE Collaboration Meeting

  21. AWAKE Spectrometer Area (2) Simon Jolly, UCL, AWAKE Collaboration Meeting

  22. AWAKE Spectrometer Area (3) Simon Jolly, UCL, AWAKE Collaboration Meeting

  23. Spectrometer Camera View (1) Simon Jolly, UCL, AWAKE Collaboration Meeting

  24. Spectrometer Camera View (2) Simon Jolly, UCL, AWAKE Collaboration Meeting

  25. Spectrometer Camera View (3) Simon Jolly, UCL, AWAKE Collaboration Meeting

  26. No Vacuum Simon Jolly, UCL, AWAKE Collaboration Meeting

  27. Vacuum Vessel (1) Simon Jolly, UCL, AWAKE Collaboration Meeting

  28. Vacuum Vessel (2)

  29. Vacuum Window Simon Jolly, UCL, AWAKE Collaboration Meeting

  30. Vacuum Window: Fresnel Lens Simon Jolly, UCL, AWAKE Collaboration Meeting

  31. No Vacuum Simon Jolly, UCL, AWAKE Collaboration Meeting

  32. Windowed Beampipe (1) Simon Jolly, UCL, AWAKE Collaboration Meeting

  33. Windowed Beampipe (2) Simon Jolly, UCL, AWAKE Collaboration Meeting

  34. Reverse Geometry Simon Jolly, UCL, AWAKE Collaboration Meeting

  35. Reverse Geometry: Beam Dump Simon Jolly, UCL, AWAKE Collaboration Meeting

  36. Reverse Geometry: Camera Position Simon Jolly, UCL, AWAKE Collaboration Meeting

  37. Reverse Geometry: Vacuum Vessel

  38. Light Tight Vessel Simon Jolly, UCL, AWAKE Collaboration Meeting

  39. Off-Axis Camera + Focussing Mirror Simon Jolly, UCL, AWAKE Collaboration Meeting

  40. Off-Axis Camera: CNGS Tunnel Simon Jolly, UCL, AWAKE Collaboration Meeting

  41. Spectrometer Status • Preliminary Geant4 scintillator results encouraging: • ~100,000 photons into camera without additional optics. • Some results need more investigation… • Work ongoing to optimise experimental layout: • We need a vacuum vessel for protons, but what about electrons? • Is screen compatible with vacuum? • Open questions: • Good field region within dipole. • Optimum camera distance from beamline to minimise damage but maximise light. • Electron/photon transition from vacuum to atmosphere (light tight). • Fresnel lens/Herschelian Telescope optics. • “Modifications” to CNGS tunnel… Simon Jolly, UCL, AWAKE Collaboration Meeting

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