Energetic neutron beams generated from femtosecond laser plasma interactions

Experiments at the HERCULES laser facility have produced directional neutron beams with energies up to 16.8(±0.3) MeV using 12d(d,n)23He,73Li(p,n)47Be,and37Li(d,n)48Be reactions. Efficient 12Li(d,n)48Be reactions required the selective acceleration of deuterons through the introduction of a deuterated plastic or cryogenically frozen D2O layer on the surface of a thin film target. The measured neutron yield was ≤1.0 (±0.5)×107 neutrons/sr with a flux 6.2(±3.7) times higher in the forward direction than at 90°. This demonstrates that femtosecond lasers are capable of providing a time averaged neutron flux equivalent to commercial 12d(d,n)23He generators with the advantage of a directional beam with picosecond bunch duration.