Referierte Publikationen

With the rapid development of high-power petawatt class lasers worldwide, exploring physics in the strong field QED regime will become one of the frontiers for laser–plasma interactions research. Particle-in-cell codes, including quantum emission processes, are powerful tools for predicting and analyzing future experiments where the physics of relativistic plasma is strongly affected by strong field QED processes. The spin/polarization dependence of these quantum processes has been of recent interest. In this article, we perform a parametric study of the interaction of two laser pulses with an ultrarelativistic electron beam. The first pulse is optimized to generate high-energy photons by nonlinear Compton scattering and efficiently decelerate electron beam through the quantum radiation reaction. The second pulse is optimized to generate electron–positron pairs by the nonlinear Breit–Wheeler decay of photons with the maximum polarization dependence. This may be experimentally realized as a verification of the strong field QED framework, including the spin/polarization rates.

The investigation of spin and polarization effects in ultra-high intensity laser–plasma and laser–beam interactions has become an emergent topic in high-field science recently. In this paper, we derive a relativistic kinetic description of spin-polarized plasmas, where quantum-electrodynamics effects are taken into account via Boltzmann-type collision operators under the local constant field approximation. The emergence of anomalous precession is derived from one-loop self-energy contributions in a strong background field. We are interested, in particular, in the interplay between radiation reaction effects and the spin polarization of the radiating particles. For this, we derive equations for spin-polarized quantum radiation reaction from moments of the spin-polarized kinetic equations. By comparing with the classical theory, we identify and discuss the spin-dependent radiation reaction terms and radiative contributions to spin dynamics.

We investigate the suitability of using GeV laser wakefield accelerated electron beams to measure strong, B > 0.1 MT, magnetic fields. This method is explored as an alternative to proton deflectometry, which cannot be used for quantitative measurement using conventional analysis techniques at these extreme field strengths. Using such energetic electrons as a probe brings about several additional aspects for consideration, including beam divergence, detectors, and radiation reaction, which are considered here. Quantum radiation reaction on the probe is found to provide an additional measurement of the strength and length of fields, extending the standard deflectometry measurement that can only measure the path integrated fields. An experimental setup is proposed and measurement error is considered under near-term experimental conditions.

We measured the angular distribution of the subsequently emitted Lyman-α 1 transition of Xe53+* ions following nonradiative electron capture in collisions of 197 MeV u−1 Xe54+ projectiles with gaseous krypton target. The alignment of the projectile 2p 3/2 state and the relative population of its magnetic substates were further deduced. In contrast to the available lower energy results (Yang et al 2020 Phys. Rev. A 102 042803), it is found that at 197 MeV u−1 the Lyman-α 1 radiation becomes much less anisotropic and the magnetic substates are nearly statistically populated. Moreover, the experimental findings are compared with the results of the corresponding radiative electron capture mechanism, obviously different energy dependence of the magnetic-substate population is obtained and discussed using semiclassical arguments, which help reveal the population mechanism of excited states in collisions of highly charged high-Z ions with atoms.

Upcoming and planned experiments combining increasingly intense lasers and energetic particle beams will access new regimes of nonlinear, relativistic, quantum effects. This improved experimental capability has driven substantial progress in QED in intense background fields. We review here the advances made during the last decade, with a focus on theory and phenomenology. As ever higher intensities are reached, it becomes necessary to consider processes at higher orders in both the number of scattered particles and the number of loops, and to account for non-perturbative physics (e.g. the Schwinger effect), with extreme intensities requiring resummation of the loop expansion. In addition to increased intensity, experiments will reach higher accuracy, and these improvements are being matched by developments in theory such as in approximation frameworks, the description of finite-size effects, and the range of physical phenomena analysed. Topics on which there has been substantial progress include: radiation reaction, spin and polarisation, nonlinear quantum vacuum effects and connections to other fields including physics beyond the Standard Model.

We perform a study on Rayleigh scattering of highly linearly polarized hard x rays on a thin Au foil target. In the study the angular distribution of the scattered radiation is analyzed in a relativistic regime both within and out of the plane of polarization of the incident beam. Within this experiment we scatter a synchrotron beam with a photon energy of 175 keV on a high-Z target foil, namely, gold. Our findings correlate well with state-of-the-art calculations of the scattering process performed in the framework of quantum electrodynamics and may have considerable impact on future experiments regarding a polarization-resolved analysis of Delbrück scattering. Furthermore, we show that the angular distribution of Rayleigh scattering can be used for a highly sensitive determination of the degree and orientation of the linear polarization of the incident hard-x-ray beam, if we rely on the theoretical framework.