Spectral shaping of laser generated proton beams

The rapid progress in the field of laser particle acceleration has stimulated a debate about the promising perspectives of laser based ion beam sources. For a long time, the beams produced exhibited quasi-thermal spectra. Recent proof-of-principle experiments demonstrated that ion beams with narrow energy distribution can be generated from special target geometries. However, the achieved spectra were strongly limited in terms of monochromacity and reproducibility. We show that microstructured targets can be used to reliably produce protons with monoenergetic spectra above 2 MeV with less than 10% energy spread. Detailed investigations of the effects of laser ablation on the target resulted in a significant improvement of the reproducibility. Based on statistical analysis, we derive a scaling law between proton peak position and laser energy, underlining the suitability of this method for future applications. Both the quality of the spectra and the scaling law are well reproduced by numerical simulations

Nuclear activation techniques for analysis of laser induced energetic protons

With the very rapid development of high intensity lasers, very high protons fluxes (at least 10$^{13}$ protons are expected in a few picoseconds bunch) will be available which cannot be characterized by usual detection techniques. For that purpose, we have developed a method in which the particles induce nuclear reactions in a stack of copper foils leading to β$^{+}$ emitters of short periods which can be detected with a very good signal to noise ratio. The initial kinetic energy distribution of the incident particles is reconstructed from the number of reactions induced in each foil. This technique has been validated at the 12 MV Tandem of CEA/DAM Bruyères-le-Châtel and used at the 100TW laser of LULI to characterize laser-accelerated proton beams. In the latter case, comparison is made with the results obtained with radiochromic films

Nuclear activation techniques for analysis of laser induced energetic protons

With the very rapid development of high intensity lasers, very high protons fluxes (at least 10$^{13}$ protons are expected in a few picoseconds bunch) will be available which cannot be characterized by usual detection techniques. For that purpose, we have developed a method in which the particles induce nuclear reactions in a stack of copper foils leading to β$^{+}$ emitters of short periods which can be detected with a very good signal to noise ratio. The initial kinetic energy distribution of the incident particles is reconstructed from the number of reactions induced in each foil. This technique has been validated at the 12 MV Tandem of CEA/DAM Bruyères-le-Châtel and used at the 100TW laser of LULI to characterize laser-accelerated proton beams. In the latter case, comparison is made with the results obtained with radiochromic films