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Acceleration in Extreme Shocks: from the microphysics to laboratory and astrophysics scenarios

Final Report Summary - ACCELERATES (Acceleration in Extreme Shocks: from the microphysics to laboratory and astrophysics scenarios)

Cosmic rays are the most energetic particles in the Universe. Their origin, and their cosmic accelerators are open long standing questions, closely tied to extreme plasma physics processes, and where a close interplay between the nonlinear processes at the micro scale and the global dynamics is critical. ACCELERATES aimed to unveil the physics of the cosmic ray accelerators, thought to be relativistic shocks, by performing large scale numerical simulations resorting to the largest supercomputers in the World, supported by theoretical studies, and by identifying the laboratory scenarios where collisionless shock waves can be generated by using the most intense lasers and relativistic particle beams.

ACCELERATES opened new avenues between theoretical and massive computational studies, laboratory experiments and astrophysical observations. It demonstrated unprecedented parallel scalability of the numerical tool used in the project resorting to the largest supercomputer in the World. A novel mechanism to generate collsionless shocks in the laboratory with intense lasers has been identified and this mechanism can be used, not only to understand the fundamental physics of cosmic rays acceleration, but also to accelerate protons to energies relevant for proton cancer therapy. This mechanism has been confirmed in experiments performed in collaboration with UCLA. The parameter map for the excitation of collisionless shocks in the laboratory has also been determined and illustrated with large scale simulations. The relevant conditions for the excitation of shock waves with laboratory relativistic electron beams, such as those available in particle accelerators, have also been determined and have triggered experimental efforts worldwide to confirm our findings. The predicted radiated light, corresponding to signatures in the polarization of light, will allow for a comparison between experiments and astrophysical observations, thus closing the conceptual loop between in silico science, laboratory experiments, and astronomical observations.