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Use of scintillation screens for high current beams

Use of scintillation screens for high current beams. Eiko Gütlich, Peter Forck GSI, Beam Diagnostics Group. Motivation Overview Beams and Szintillators Principle of setup Experimental setup Camera features / Timing Observed image parameters Experimental results Conclusions / Outlook.

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Use of scintillation screens for high current beams

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  1. Use of scintillation screens for high current beams Eiko Gütlich, Peter Forck GSI, Beam Diagnostics Group Motivation Overview Beams and Szintillators Principle of setup Experimental setup Camera features / Timing Observed image parameters Experimental results Conclusions / Outlook Use of scintillation screens for high current beams Eiko Gütlich

  2. Motivation • Scintillator screens are widely used since decades • Less experience with scintillator screens at UNILAC • Essential part of pepperpot device (single shot emittance measurement) • For high currents unknown: • Spatial resolution • Ageing effects / Lifetime • Dynamical behaviour ZrO2 , 1 Pulse with 1*109 238U28+ ions in 100µs Use of scintillation screens for high current beams

  3. Ion Beams Use of scintillation screens for high current beams

  4. Scintillators Use of scintillation screens for high current beams

  5. Principle of Profile Measurement Beam Support movement Use of scintillation screens for high current beams

  6. Principle and Setup Beam Support movement Use of scintillation screens for high current beams

  7. Principle and Setup Beam Support movement Use of scintillation screens for high current beams

  8. Target Holder / Camera • Holder allows to: • investigate 6 scintillator materials • in one machine run • at the same position  constant beam conditions Camera: AVT Marlin VGA resolution 8Bit monochrom Spatial Resolution: 10 Px/mm screen dimensions: ø30mm x 1mm Use of scintillation screens for high current beams

  9. Camera Timing Camera timing for pulsed ion beam • Allows to: • Observe complete macro pulse • Measurement of afterglow Max. 15 Frames / s Use of scintillation screens for high current beams

  10. Observed Image Parameters Use of scintillation screens for high current beams

  11. Observed Image Parameters Vertical projection of image (sum over rows) Horizontal projection of image (sum over columns) Use of scintillation screens for high current beams

  12. Observed Image Parameters Vertical projection of image (sum over rows) Horizontal projection of image (sum over columns) • Projection; • Integral intensity (Light yield) • Center of projections • Standard deviation (Sigma) • Skewness • Kurtosis Use of scintillation screens for high current beams

  13. Observed Image Parameters Vertical projection of image (sum over rows) Horizontal projection of image (sum over columns) Comparison • Projection; • Integral intensity (Light yield) • Center of projections • Standard deviation (Sigma) • Skewness • Kurtosis Use of scintillation screens for high current beams

  14. Degradation Effects Degradation of Quartzglass: Ce within 200 macro Pulses 1st macro Pulse 200th macro Pulse Beam parameters: 238U28+, 8*108 Ions/Pulse in 100µs , ~35µA ,1Hz Use of scintillation screens for high current beams

  15. Degradation Effects Degradation of Quartzglass: Ce within 200 macro Pulses 1st macro Pulse 200th macro Pulse Region of interest Beam parameters: 238U28+, 8*108 Ions/Pulse in 100µs , ~35µA ,1Hz Use of scintillation screens for high current beams

  16. Deformation of Beam Profil 1st Pulse 50th Pulse 100th Pulse 200th Pulse  Strong profile deformation Characterisation: first 4 moments Beam parameters: 238U28+, 8*108 Ions/Pulse in 100µs , ~35µA ,1Hz Use of scintillation screens for high current beams

  17. Behaviour for degradation Decrease in light yield Change in Skewness Kurtorsis becomes different from 0 0 = Gaussian Increase in profile width Beam parameters: 40Ar10+, 2*109Ions/Pulse in 100µs, ~30µA, 1Hz Use of scintillation screens for high current beams

  18. Light Yield and Profile Width @ low intensity Beam parameters: 40Ar10+ 2*109Ions/Pulse in 100µs, ~30µA 1Hz 1000 macro pulses Difference of 14% in profile width is not negligible for pepper-pot Reproducible behaviour !No chromatic aberration! Same beam parameters for all samples Use of scintillation screens for high current beams

  19. Skewness and Kurtosis @ low intensity Beam parameters: 40Ar10+ 2*109Ions/Pulse in 100µs, ~30µA 1Hz Different beam shape Average temperature (Backside of ZrO2:Mg) 47°C Same beam parameters for all samples Use of scintillation screens for high current beams

  20. Light Yield and Profile Width @ higher intensity At 10 timeshigher beam current Beam parameters: 40Ar10+ 2*1010Ions/Pulse in 100µs, ~ 0,3mA 2,6Hz 2200 macro pulses Light yield and profile width depend on ion dose! Possible reasons: surface modification, temperature dependency Average temperature (Backside of ZrO2:Mg) ~240°C 3 min. break Same beam parameters for all samples Use of scintillation screens for high current beams

  21. Light Yield and Profile Width @ very low intensity Beam parameters: 12C2+ 5*106Ions/Pulse in 100µs, ~17nA 12,6Hz 15000 macro pulses Difference of 25% in profile width is not negligible for pepper-pot Average temperature (Backside of ZrO2:Mg) ~RT Same beam parameters for all samples Use of scintillation screens for high current beams

  22. Decay time of Al2O3:Cr y = a*e(-t/t1) + b*e(-t/t2) t1: 1.0919 ms t2: 3.8263 ms there might be faster components Other materials t2<30µs Use of scintillation screens for high current beams

  23. Colours Use of scintillation screens for high current beams

  24. Conclusions \ Outlook • What has been done…. • Quantitative investigations on different materials • Materials show different, but reproducible behaviour • Profile width depends on scintillator material! • Light yield AND profile width depend on ion dose! •  Winners are ZrO2 , ZrO2 + Mg and undoped Quartzglass • The next steps: • investigate the spectra of the scintillators • analysis of the thermal effect • investigate surface modifications • approach for a theoretical discription of the observed effects • long-term objective: scintillator for pepper-pot-device Use of scintillation screens for high current beams

  25. Thanks for your attention Use of scintillation screens for high current beams Eiko Gütlich

  26. Different Ion Energies Ni beam (5.5 MeV/u) on Herasil 102. The target is moving through the beam. In the middle the disc was irradiated by an argon beam with 11.4 MeV/u. Use of scintillation screens for high current beams

  27. Changing Surface Modification Use of scintillation screens for high current beams

  28. ?Temperature Effect? Use of scintillation screens for high current beams

  29. Scintillators • The kinetic energy of the ion is converted to light • Conversion with good quantum efficiency • Light yield directly proportional to number of particles • Small absorption of induced light • Small temperature dependency of scintillation • Producible in appropriate size Use of scintillation screens for high current beams

  30. Camera Features Camera resolution ~ 10 Px/mm Light yield of CdWO4 Spectral sensitivity of CCD 30mm BGO CdWO4 YAG Camera: AVT Marlin Use of scintillation screens for high current beams

  31. Skewness and Kurtosis @ higher intensity Beam parameters: 40Ar10+ 2*1010Ions/Pulse in 100µs, ~ 0,3mA 2,6Hz 3 min. break Same beam parameters for all samples Use of scintillation screens for high current beams

  32. Skewness and Kurtosis @ very low intensity Beam parameters: 12C2+ 5*106Ions/Pulse in 100µs, ~17nA 12,6Hz Same beam parameters for all samples Use of scintillation screens for high current beams

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