Generation of energetic (>15 MeV) neutron beams from proton- and deuteron-driven nuclear reactions using short pulse lasers

A roadmap is proposed for the production of high-energy (>15 MeV) neutrons using short pulse lasers. Different approaches are suggested for the two limiting cases of small ( E 1 ≪ Q ) and large ( E 1 ≫ Q ) projectile energies E 1 depending on the Q -value of the nuclear reaction. The neutron fluence from many converter materials is evaluated for two projectiles: protons and deuterons. We found profound differences between proton- and deuteron-driven reactions with regard to both converter material and generated neutron fluence. The optimum converter material for deuteron-driven reactions is low-Z elements such as Li and Be, while for proton-driven reactions the converter material is not critical. For a projectile energy of 50 MeV the deuteron-driven reactions are two orders of magnitude more efficient compared to the proton-driven reactions. Two-dimensional particle-in-cell simulations have been performed for laser pulses with peak intensity 3 × 10 20 W cm −2 , pulse duration 40 fs, spot size 5 µ m and energy 3 J interacting with ultrathin (0.1 µ m) CD foil. The calculated deuteron beam is highly directional along the laser propagation direction with maximum energy of 45 MeV. The interaction of the deuteron beam with a lithium converter and the production of neutrons is modeled using a Monte Carlo code. The computed neutron spectra show that a forward directed neutron beam is generated with an opening angle of ∼1 sr, maximum energy of 60 MeV and a fluence in the forward direction 1.8 × 10 8 n sr −1 , ∼20% of which are with energy above 15 MeV.