Jonathan Richard Warwick's research works | Queen's University Belfast, Belfast (QUB) and other places

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Multi-GeV Electron Acceleration in Wakefields Strongly Driven by Oversized Laser Spots

Article

Full-text available

May 2024

Experiments were performed on laser wakefield acceleration in the highly nonlinear regime. With laser powers P < 250 TW and using an initial spot size larger than the matched spot size for guiding, we were able to accelerate electrons to energies E max > 2.5 GeV , in fields exceeding 500 GV m − 1 , with more than 80 pC of charge at energies E > 1 G...

FIG. 1. Sketch of the experimental setup. Three different...

FIG. 2. Measured electron spectrum (black solid line) and Maxwellian...

FIG. 8. Positron temporal distributions obtained with FLUKA at the...

FIG. 12. Example of energy selection after the dogleg. All...

Ultrashort, MeV-scale laser-plasma positron source for positron annihilation lifetime spectroscopy

Article

Full-text available

Jul 2021

Submicron defects represent a well-known fundamental problem in manufacturing since they can significantly affect performance and lifetime of virtually any high-value component. Positron annihilation lifetime spectroscopy is arguably the only established method capable of detecting defects down to the subnanometer scale but, to date, it only works...

Ultra-short, MeV-scale laser-plasma positron source for positron annihilation lifetime spectroscopy

Preprint

Sep 2020

Sub-micron defects represent a well-known fundamental problem in manufacturing since they significantly affect performance and lifetime of virtually any high-value component. Positron annihilation lifetime spectroscopy is arguably the only established method able to detect defects down to the sub-nanometer scale but, to date, it only works for surf...

FIG. 1. a.-b. Simulated phase-space of 1 GeV electrons (a.) and...

FIG. 2. Experimental setup. Cartoon depicting the experimental setup....

FIG. 3. Optimisation of the primary electron beam. Average spectra...

Non-invasive characterisation of a laser-driven positron beam

Article

Full-text available

Mar 2020

We report on an indirect and non-invasive method to simultaneously characterise the energy-dependent emittance and source size of ultra-relativistic positron beams generated during the propagation of a laser-wakefield accelerated electron beam through a high-Z converter target. The strong correlation of the geometrical emittance of the positrons wi...