Figure 2.

Differential PIXE scheme and properties of the laser-driven ion source. (a) Schematic representation of differential PIXE. (b) Snapshot at 267 fs of the macro-protons for the PIC simulation performed with a₀ = 4.0. Only the central region of the simulation box is shown and the macro-particles are colored according to their energy. The two black lines indicate the normal to the target surface ($\hat{n}$) and a slightly tilted direction ($\hat{t}$). (c) Proton energy spectra for all the macro-particles (purple), for the particles propagating along $\hat{n}$ (light blue) and $\hat{t}$ (green). (d) Angular and energy distribution of the protons for the PIC simulation performed with a₀ = 4.0 (t = 267 fs). Each panel shows the angular distribution at the corresponding energy range.