C. D. Murphy
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View article: Imaging of dynamic processes in materials with a laser-wakefield accelerator
Imaging of dynamic processes in materials with a laser-wakefield accelerator Open
Betatron x rays generated from laser-wakefield accelerators are a promising source for imaging dynamic processes in materials. Here, we present proof-of-concept imaging of microstructural evolution in a hypermonotectic Al - Bi alloy, which…
View article: Spectral phase control for optimized ionization injection in laser wakefield acceleration
Spectral phase control for optimized ionization injection in laser wakefield acceleration Open
Generating narrow energy spread beams from laser wakefield accelerators with minimal dark current is important for many applications. We present an automated experiment using Bayesian optimization to control the laser spectral phase and fo…
View article: High brightness multi-MeV photon source driven by a petawatt-scale laser wakefield accelerator
High brightness multi-MeV photon source driven by a petawatt-scale laser wakefield accelerator Open
We present an experimental demonstration of a bright multi-MeV gamma source driven by a petawatt laser. The source generates on average $(1.2\pm0.6)\times10^9$ photons above 1 MeV per pulse, exceeding those of previous all-optical sources …
The effect of the electron’s spin magnetic moment on quantum radiation in strong electromagnetic fields Open
Ultra-intense laser pulses can create sufficiently strong fields to probe quantum electrodynamics effects in a novel regime. By colliding a 60 GeV electron bunch with a laser pulse focussed to the maximum achievable intensity of 10 23 W cm…
View article: Target sensitivity study of density transition-injected electrons in laser wakefield accelerators
Target sensitivity study of density transition-injected electrons in laser wakefield accelerators Open
While plasma-based accelerators have the potential to positively impact a broad range of research topics, a route to application will only be possible through improved understanding of their stability. We present experimental results of a …
View article: Bounding elastic photon-photon scattering at $\sqrt s \approx 1\,$MeV using a laser-plasma platform
Bounding elastic photon-photon scattering at $\sqrt s \approx 1\,$MeV using a laser-plasma platform Open
We report on a direct search for elastic photon-photon scattering using x-ray and $\gamma$ photons from a laser-plasma based experiment. A gamma photon beam produced by a laser wakefield accelerator provided a broadband gamma spectrum exte…
Observation of quantum effects on radiation reaction in strong fields Open
Radiation reaction, the force experienced by an accelerated charge due to radiation emission, has long been the subject of extensive theoretical and experimental research. Experimental verification of a quantum, strong-field description of…
View article: Nuclear imaging to diagnose and correct target-driver registration at high-repetition-rate for improved reactor efficiency
Nuclear imaging to diagnose and correct target-driver registration at high-repetition-rate for improved reactor efficiency Open
Inertial Confinement Fusion produces energy from a burning plasma lasting a fraction of a nanosecond. Power plant designs based on Inertial Fusion Energy (IFE) will need to ignite targets 1-10 times a second, fired as projectiles into a ch…
View article: Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies
Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies Open
Low convergence ratio implosions (where wetted-foam layers are used to limit capsule convergence, achieving improved robustness to instability growth) and auxiliary heating (where electron beams are used to provide collisionless heating of…
View article: A coded aperture with sub-mean free-path thickness for neutron implosion geometry imaging on inertial confinement fusion and inertial fusion energy experiments
A coded aperture with sub-mean free-path thickness for neutron implosion geometry imaging on inertial confinement fusion and inertial fusion energy experiments Open
Inertial confinement fusion and inertial fusion energy experiments diagnose the geometry of the fusion region through imaging of the neutrons released through fusion reactions. Pinhole arrays typically used for such imaging require thick s…
View article: Plasma density profile reconstruction of a gas cell for Ionization Induced Laser Wakefield Acceleration
Plasma density profile reconstruction of a gas cell for Ionization Induced Laser Wakefield Acceleration Open
Laser-driven plasma wakefields can provide hundreds of MeV electron beam in mm-range distances potentially shrinking the dimension of the actual particle accelerators. The plasma density plays a fundamental role in the control and stabilit…
View article: Mechanisms to control laser-plasma coupling in laser wakefield electron acceleration
Mechanisms to control laser-plasma coupling in laser wakefield electron acceleration Open
Experimental results, supported by precise modelling, demonstrate optimisation of a plasma-based injector with intermediate laser pulse energy ($<1$ J), corresponding to a normalised vector potential $a_0 = 2.15$, using ionisation injectio…
Absolute keV x-ray yield and conversion efficiency in over dense Si sub-petawatt laser plasma Open
Laser-produced plasmas are bright, short sources of x-rays commonly used for time-resolved imaging and spectroscopy. Their usage implies accurate knowledge of laser-to-x-ray conversion efficiency (CE), spectrum, photon yield and angular di…
View article: Laser Driven Nuclear physics at ELINP
Laser Driven Nuclear physics at ELINP Open
High power lasers have proven being capable to produce high energy gamma rays, charged particles and neutrons to induce all kinds of nuclear reactions. At ELI, the studies with high power lasers will enter for the first time into new domai…
Absolute keV X-ray yield and conversion efficiency in over dense Si petawatt laser plasma Open
Laser-produced plasmas are bright, short sources of X-rays often used for time-resolved imaging and spectroscopy. Absolute measurement requires accurate knowledge of laser-to-x-ray conversion efficiencies, spectrum, photon yield and angula…
A laser–plasma platform for photon–photon physics: the two photon Breit–Wheeler process Open
We describe a laser–plasma platform for photon–photon collision experiments to measure fundamental quantum electrodynamic processes. As an example we describe using this platform to attempt to observe the linear Breit–Wheeler process. The …
Effect of laser temporal intensity skew on enhancing pair production in laser—electron-beam collisions Open
Recent high-intensity laser experiments (Cole et al 2018 Phys. Rev. X 8 011020; Poder et al 2018 Phys. Rev. X 8 031004) have shown evidence of strong radiation reaction in the quantum regime. Experimental evidence of quantum effects on rad…
View article: Characterisation of a laser plasma betatron source for high resolution x-ray imaging
Characterisation of a laser plasma betatron source for high resolution x-ray imaging Open
We report on the characterisation of an x-ray source, generated by a laser-driven plasma wakefield accelerator. The spectrum of the optimised source was consistent with an on-axis synchrotron spectrum with a critical energy of keV and the …
View article: Optimization of a laser plasma-based x-ray source according to WDM absorption spectroscopy requirements
Optimization of a laser plasma-based x-ray source according to WDM absorption spectroscopy requirements Open
X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter. It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the spectral range of int…
View article: Development of control mechanisms for a laser wakefield accelerator-driven bremsstrahlung x-ray source for advanced radiographic imaging
Development of control mechanisms for a laser wakefield accelerator-driven bremsstrahlung x-ray source for advanced radiographic imaging Open
A high power laser was used to accelerate electrons in a laser-driven wakefield accelerator. The high energy electrons were then used to generate an x-ray beam by passing them through a converter target. This bremsstrahlung source was char…
Application of compact laser-driven accelerator X-ray sources for industrial imaging Open
X-rays generated by betatron oscillations of electrons in a laser-driven plasma accelerator were characterised and applied to imaging industrial samples. With a 125 TW laser, a low divergence beam with 7.52.6 108 photons mrad−2 per pulse w…
Characterization of flowing liquid films as a regenerating plasma mirror for high repetition-rate laser contrast enhancement Open
In this paper, we characterize a high repetition-rate regenerating plasma mirror produced by the thin film of liquid formed when two laminar streams collide. The use of a flowing liquid film is inexpensive and the interaction surface refre…
View article: Coded apertures with scatter and partial attenuation for high-energy high-resolution imaging
Coded apertures with scatter and partial attenuation for high-energy high-resolution imaging Open
Laser-plasma x-ray sources have garnered interest from various communities due to their ability to generate high photon-energies from a small source size. The passive imaging of high energy x-rays and neutrons is also a useful diagnostic i…
View article: Effect of plastic coating on the density of plasma formed in Si foil targets irradiated by ultra-high-contrast relativistic laser pulses
Effect of plastic coating on the density of plasma formed in Si foil targets irradiated by ultra-high-contrast relativistic laser pulses Open
The formation of high energy density matter occurs in inertial confinement fusion, astrophysical, and geophysical systems. In this context, it is important to couple as much energy as possible into a target while maintaining high density. …
View article: Automation and control of laser wakefield accelerators using Bayesian optimization
Automation and control of laser wakefield accelerators using Bayesian optimization Open
Laser wakefield accelerators promise to revolutionize many areas of accelerator science. However, one of the greatest challenges to their widespread adoption is the difficulty in control and optimization of the accelerator outputs due to c…
Laser wakefield acceleration with active feedback at 5 Hz Open
We describe the use of a genetic algorithm to apply active feedback to a laser wakefield accelerator at a higher power (10 TW) and a lower repetition rate (5 Hz) than previous work. The temporal shape of the drive laser pulse was adjusted …
Plasma Wakefield Accelerator Research 2019 - 2040: A community-driven UK roadmap compiled by the Plasma Wakefield Accelerator Steering Committee (PWASC) Open
The acceleration gradients generated in a laser- or beam-driven plasma wakefield accelerator are typically three orders of magnitude greater than those produced by a conventional accelerator, and hence plasma accelerators can open a route …
Laser wakefield acceleration with active feedback at 5 Hz Open
The data and code used to produce the plots in Dann et al., "Laser wakefield acceleration with active feedback at 5 Hz", Phys. Rev. Accel. Beams (2019). This is a sub-set of the data collected during an experiment investigating the use of …
Laser wakefield acceleration with active feedback at 5 Hz Open
The data and code used to produce the plots in Dann et al., "Laser wakefield acceleration with active feedback at 5 Hz", Phys. Rev. Accel. Beams (2019). This is a sub-set of the data collected during an experiment investigating the use of …
Laser driven sources for a new generation of high resolution hard x-ray CT machines Open
A new type of particle accelerator that uses lasers to accelerate particles, called Laser Wakefield Acceleration (LWFA), is becoming a wide spread tool in the scientific community. These compact accelerators are capable of delivering very …