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 $d12(d,n)23He,Li73(p,n)47Be,andLi37(d,n)48Be$ reactions. Efficient $Li12(d,n)48Be$ 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 $d12(d,n)23He$ generators with the advantage of a directional beam with picosecond bunch duration.