Extended characterization of alpha particles via laser-induced p- ¹¹ B fusion reaction in silicon hydrogenated boron-doped thin targets

The nuclear fusion channel of the p-11B reaction producing α particles with multi-MeV kinetic energies was induced by a sub-nanosecond laser pulse focused onto 10 μm thick boron-doped thin targets at intensities of ∼ 1016 W/cm2. A full characterization in terms of α particle flux and angular distribution was performed thanks to the simultaneous use of several diagnostics (time-of-flight detectors, nuclear track detectors, and Thomson Parabola spectrometers), which enabled to measure key features of particles produced both in the backward (target front side) and forward (target rear side) directions. Maximum α particle flux and cut-off energy were recorded at small detection angles with respect to the target normal in the backward direction. The maximum kinetic energy shown by the α-particles produced in the nuclear fusion reaction was ascribable to a post-accelerating transient electric field present in the laser-generated plasma, in agreement with our previous preliminary results.