High-brightness plasma-based Compton backscattering source for high energy physics

  • Paul Scherkl

Student thesis: Doctoral Thesis


Exciting, probing and manipulating the quantum states of nuclei is crucial to many scientific, industrial, medical and defence applications of high energy physics. Inverse Compton scattering (ICS) offers the necessary MeV-level photon energies along with highly directed and collimated pulse profiles. However, respective facilities are scarce as the large underlying particle accelerators cause high costs. Plasma accelerators, in contrast, offer orders of magnitude higher accelerating fields and can operate sensibly priced in considerably smaller laboratories. State-of-the-art experiments have routinely shown generation of dense electron beams suitable for MeV-photon pulses with extremely high peak brilliance. Yet, plasma accelerators suffer from large energy spread and emittance that cause spectral broadening impractical for many nuclear applications.This work investigates the prospects of plasma photocathode wakefield accelerators generating low-emittance, high-quality electron beams for ICS. An important component is the experimental demonstration of a novel, plasma-based diagnostic for spatiotemporal synchronisation and alignment of electron and laser beams.This multi-shot method yields absolute time-of-arrival accuracy of ~16 fs and alignment accuracy of 4 μm. It has facilitated the word's first experimental realisation of a plasma photocathode and the plasma torch injection method. These experiments represent milestones towards highest-quality electron beam production, and are fundamental to plasma-based generation of brilliant, narrow-bandwidth and MeV-level-ray sources. Extensive simulations investigate their production and reveal unprecedented single-shot peak brilliance of ~1 1025 photons s-1 mm-2 mrad-2 0.1%BWat 0.4MeV to 9MeV.This work further outlines the generation of inherently synchronised and brilliant-ray pairs, which constitute temporally and spectrally fully separable multi-colour radiation. The underlying effect can further minimise electron beam energy spread.This is shown to shrink the relative -ray bandwidth to 2.3% at 2.4MeV, and overcomes one of the major problems in plasma accelerators and ICS sources. Each part of this work advances its respective research area, yet combined they promise the highest-quality photon sources for nuclear physics applications.
Date of Award13 Jan 2020
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorBernhard Hidding (Supervisor) & Dino Jaroszynski (Supervisor)

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