Ion diagnostics for laserdriven ion beam experiments at
Ion diagnostics for laser-driven ion beam experiments at CLF Ceri Brenner and James Green
Vulcan • • Multi-beam facility and single Petawatt laser 600 J, ~500 fs, 1021 Wcm-2 1 shot every 30 mins Near-100 Me. V protons, up to 10% conversion efficiency A. Higginson et al. Nat. Comms. 9 (2018) Gemini • • Dual beam Petawatt class facility ~14 J, 40 -45 fs, 6 x 1020 Wcm-2 1 shot every 20 seconds ~ 30 Me. V protons C. Scullion et al. Phys. Rev. Lett. 119 (2017)
Requirements • • • Established detectors In-situ measurement of: • Ion energies • Ion species distribution • Beam profile • Fluence / Conversion Efficiency • Radiochromic Film • CR-39 Track detectors • Image Plate EMP Resistance High repetition rate operation Robust – radiation and laser damage Calibrated and Characterised Minimal user intervention • MCPs • Scintillators • Phosphor screens • TOF detectors In-situ detectors
Thomson Parabola Beam profiler • • 1 D Multi-species ion spectrometer MCP or Scintillator detector P. Bolton et al. Phys. Med. 30 (2014) • • • 2 D ion beam profiler Organic scintillator detectors 3 spectral channels Time of Flight • • RCF Scintillator J. S. Green et al. Proc. SPIE 8079 (2011) Diamond / Si. C detectors 80 -350 ps time resolution V. Scuderi et al. J. Inst 12 (2017) Photo-peak Protons Ions
Optical fibre bundles to relay image away Optical Core C o r e Optical Cladding 60 um 60 u m High resolution 800 x 800 fibre bundles High resolution (800 x 800) Fibre bundle can be used to transport an optical image away from the interaction point to a location where the EMP is below the threshold for causing disruption to a sensitive 16 bit CCD
2 D Ion detector head development 90 mm 100 mm • • • 3 scintillators, each emitting at a separate central emission wavelength Light coupled into fibre bundle, then separated at camera into 3 distinct channels Scintillator thickness determines energy observation window Each scintillator has need to avoid optical excitation within scintillator stack. . Incident Protons Scintillator 3 (Blue) • Scintillator 2 (Green) Compact scintillator beam head Scintillator 1 (Orange • Incident Protons Detector head 1 - 4. 5 Me. V 7 -9 Me. V 10. 5 -14 Me. V 50 nm Al 100 nm Al
Scintillator Developments Old design Spectral overlap • Significant spectral overlap using old scintillators gives cross-talk into the neighbouring channels • This limited our ability to only dual channel monitors • Scintillators with different spectral responses have been developed, enabling three colour channel imaging New design reduced
Scintillator resolution • • Organic Scintillator resolution investigated Cyclotron source at 11 and 20 Me. V “Traditional” RCF limited to scanner resolution of ~20 μm EJ-228 scintillator resolution of 200300 μm in image plane (20 -30 μm) in subject plane with x 10 magnifcation M. Manuel et al. Nuc. Inst. Methods 913 (2019)
EPAC – Extreme Photonics Applications Centre 10 Hz petawatt laser 2 target areas For academic and industrial user community For insight, innovation, and discovery with laser-driven beams of electrons, x-rays, ions, neutrons, …
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