New insights in laser-generated ultra-intense gamma-ray and neutron sources for nuclear applications and science
Abstract
Ultra-intense MeV photon and neutron beams are indispensable tools in many research fields such as nuclear, atomic and material science as well as in medical and biophysical applications. For astrophysical applications aimed for laboratory investigations, neutron fluxes in excess of 1021 n/(cm2 s) are required. Such ultra-high fluxes are unattainable with existing conventional reactor- and accelerator-based facilities. Currently discussed concepts for generating high-flux neutron beams are based on ultra-high-power multi-petawatt lasers operating at >1023 W/cm2 intensities. Here, we present a novel efficient concept for generating γ and neutron beams based on enhanced generation of direct laser accelerated electrons in relativistic laser interactions with a long-scale near critical density plasma at 1019 W/cm2 intensity. New experimental insights in the laser-driven generation of ultra-intense well-directed multi-MeV beams of photons with >1012 ph/sr and a ultra-high intense neutron source with >6×1010 neutrons per shot are presented. More than 1.4\% laser-to-gamma conversion efficiency above 10 MeV and 0.05\% laser-to-neutron conversion efficiency were recorded, already at moderate relativistic laser intensities and ps pulse duration. This approach promises a strong boost of the diagnostic potential of existing kJ PW laser systems used for ICF research.