Speaker
Description
The different types of energetic particle sources generated by PetaWatt (PW) lasers can serve for various applications in many research fields, including nuclear physics. In this presentation, we will report on recent numerical and experimental results on particle acceleration as well as neutron generation with the (~ 0.3 kJ, 0.6-1 ps, 5×10$^{18}$ Wcm$^{-2}$) PETAL and (~ 45 J, 20 fs, 10$^{22}$ Wcm$^{-2}$) Apollon laser systems.
First, we will address electron acceleration by means of the PETAL beam interacting with a gas jet of ~10$^{19}$ cm$^{-3}$ density in the self-modulated laser wakefield regime. Multidimensional particle-in-cell simulations, performed for various gas densities and lengths, foresee the generation of electron beams with energies as high as ~ 300 MeV and charge up to 100 nC. These predictions have been confirmed, as we will show, by a first experiment conducted on the LMJ-PETAL facility.
Second, we will examine, through PIC and Monte Carlo simulations, the laser acceleration of protons from thin-foil or double-layer targets and their subsequent conversion into neutrons in secondary LiF and lead targets. This setup has been investigated using both the PETAL and Apollon laser parameters. Our simulations indicate that, compared to PETAL, the more intense, tightly focused Apollon beam should produce a lower number of protons but with higher energies, so that a similar number of fast neutrons should be released from the secondary conversion target. This is also what we observe in experiments we performed both at Apollon (where up to 55 MeV protons and ~10$^8$ MeV-range neutrons were produced) and PETAL (30 MeV protons, and > 10$^9$ fast neutrons depending on the laser and converter parameters); in both cases, results reasonably agree with these predictions.
Overall, the above results open encouraging perspectives for laser-based nuclear physics studies on PW-class facilities.
