arXiv subjects

M Zepf

Publications and source records attributed to M Zepf.

3 recordsLinked to original sources

arXiv2021

Photo-induced pair production and strong field QED on Gemini

The extreme intensities obtainable with lasers such as Gemini allow non-linear QED phenomena to be investigated according to our calculations. Electron-positron pair production from a pure vacuum target, which has yet to be observed experimentally, is possibly the most iconic process. Beyond pair-production our campaign will allow the experimental investigation of currently unexplored extreme radiation regimes, like the quantum radiation dominated regime (where quantum and self-field effects become important) and non-linear Compton scattering. This is the first experiment in a multi-part campaign proposed by a major international collaboration to investigate non-linear QED. This proposal is for the first experiment in a series of 3 to achieve our most high-profile experimental goal of pair production in vacuum, but each experiment is designed to have its own tangible high-profile outcome.

physics.plasm-ph↗

arXiv2015

Selective Deuterium Ion Acceleration Using the Vulcan PW Laser

We report on the successful demonstration of selective acceleration of deuterium ions by target-normal sheath acceleration (TNSA) with a high-energy petawatt laser. TNSA typically produces a multi-species ion beam that originates from the intrinsic hydrocarbon and water vapor contaminants on the target surface. Using the method first developed by Morrison, et al.,$^{1}$ an ion beam with $>$99$\%$ deuterium ions and peak energy 14 MeV/nucleon is produced with a 200 J, 700 fs, $>10^{20} W/cm^{2}$ laser pulse by cryogenically freezing heavy water (D$_{2}$O) vapor onto the rear surface of the target prior to the shot. Within the range of our detectors (0-8.5$^{\circ}$), we find laser-to-deuterium-ion energy conversion efficiency of 4.3$\%$ above 0.7 MeV/nucleon while a conservative estimate of the total beam gives a conversion efficiency of 9.4$\%$.

physics.plasm-ph↗

arXiv2014

Fast electron propagation in Ti foils irradiated with sub-picosecond laser pulses at $Iλ^{2} > 10^{18}$ Wcm$^{-2} μm^{2}$

We have studied the propagation of fast electrons through laser irradiated Ti foils by monitoring the emission of hard X-rays and K-α radiation from bare foils and foils backed by a thick epoxy layer. Key observations include strong refluxing of electrons and divergence of the electron beam in the foil with evidence of magnetic field collimation. Our diagnostics have allowed us to estimate the fast electron temperature and fraction of laser energy converted to fast electrons. We have observed clear differences between the fast electron temperatures observed with bare and epoxy backed targets which may be due to the effects of refluxing.

physics.plasm-ph↗