High-efficiency neutron source generation from photonuclear reactions driven by laser plasma accelerator

We experimentally demonstrate the generation of an electron beam with the charge of about 200 pC, the divergence of about 7 mrad and the maximum energy of about 320 MeV from helium gas via self-injection induced by self-evolved laser pulses (3 J, 30 fs) in the plasma channel. Based on the experimental electron beam parameters, the Monte Carlo simulation code Geant4 was used to optimize the thicknesses of converters for high yield neutrons. The Monte Carlo simulation results show that the simulation neutron number can reach as high as 107 with a 5-cm-thick Pb converter, and the corresponding energy range was about 100 keV~ 1 MeV. In this work, the neutrons were detected by four bubble detectors, and the neutron yield was measured to be 3.2 × 107/shot and distributed isotropically. Moreover, the neutron generation efficiency is about 1.1 × 107/J which to best of our knowledge, is the highest compared with other laser neutron generation methods with the same laser energy. Such a laser driven pulsed neutron source could be applied to different fields like the neutron absorption spectroscopy, material science, and nuclear physics, etc.