High Energy Neutron Production from Ions Accelerated in a Nanowire Array Irradiated at Relativistic Intensities*

Ultra-high contrast short pulse laser irradiation of ordered deuterated polyethylene nanowires arrays at relativistic intensities has been demonstrated to produce flashes of neutrons resulting from D-D microscale fusion [1].  Energetic deuteron emission into a tight beam in the laser backward direction was recently reported to result from irradiation at an increased laser intensity > 1×10 ²¹ Wcm^-2 [2]. Here we use this well collimated deuteron source produced with 6-7 J laser pulses to demonstrate a laser-driven neutron generator with energies in the 10–20 MeV range.The pitcher-catcher configuration was implemented using the deuterium jets from the ultra-intense-laser-nanowire interaction (pitcher) with a conversion target (catcher) of ⁹Be, ⁷LiF or ¹⁰B. Energy spectra and yield for neutron production of different catcher targets is measured.The ⁹Be generated mostly neutrons with ~4.8 MeV energy of ~5.5×10⁶ neutrons/sr/shot. The ⁷LiF produced ~4.5×10⁶ neutrons/sr/shot with a broad energy peak in the 10–15 MeV, a range that includes the energy of D-T neutrons. Using a ¹⁰B catcher ~2×10⁶ neutrons neutrons/sr/shot were produced with an energy reaching 20–25 MeV. Using a lithium metal catcher with an improved circular cutout geometry we demonstrated the generation of an increased flux of 2×10⁷ neutrons/sr/shot, with energies in the 10–20 MeV range.