Energetic α-particle sources produced through proton-boron reactions by high-energy high-intensity laser beams

In an experiment performed with a high-intensity and high-energy laser system, $\ensuremath{\alpha}$-particle production in proton-boron reaction by using a laser-driven proton beam was measured. $\ensuremath{\alpha}$ particles were observed from the front and also from the rear side, even after a 2-mm-thick boron target. The data obtained in this experiment have been analyzed using a sequence of numerical simulations. The simulations clarify the mechanisms of $\ensuremath{\alpha}$-particle production and transport through the boron targets. $\ensuremath{\alpha}$-particle energies observed in the experiment and in the simulation reach 10--20 MeV through energy transfer from 20--30 MeV energy incident protons. Despite the lower cross sections for protons with energy above the sub-MeV resonances in the proton-boron reactions, ${10}^{8}$--${10}^{9}\phantom{\rule{4pt}{0ex}}\ensuremath{\alpha}$ particles per steradian have been detected.