Application of solid-state nuclear track detectors of the CR-39/PM-355 type for measurements of energetic protons emitted from plasma produced by an ultra-intense laser

The paper reports on applications of solid-state nuclear track detectors (SSNTDs) of the CR-39/PM-355, manufactured by Pershore Moulding Ltd., for measurements of fast protons emitted from laser-produced plasma. The experiment was performed at LULI, Ecole Politechnique, on the 100 Tera-Watt laser facility. A 1.05 μm laser pulse of 350 fs duration and intensity up to 2 × 1019 W/cm2 irradiated a thin (1–3 μm) polystyrene (PS) or Au/PS target (PS foil covered with a 0.1–0.2 μm Au layer) along the target normal. The measurements revealed that very intense MeV proton beams can be produced under specially chosen laser-target irradiation conditions. The proton beam characteristics were measured using the TOF method (ion collectors), SSNTDs, and radiochromic films (RCFs). The SSNTDs appeared to be especially useful for the experimental analysis of more energetic protons (Ep > 3 MeV). Using in the same laser shots many detector samples covered with Al foils of different thicknesses (from 15 μm up to 400 μm) it was possible to estimate energy spectra of protons emitted under various irradiation conditions. The most energetic protons (of energy up to 10 MeV) and the most intense proton beams were generated from a double-layer Au/PS target.