Ultra-short, beamed source of laser-driven epithermal neutrons

Development of intense neutron sources driven by laser will enable a range of scientific investigations and new opportunities for industrial and medical applications. In particular, an ultra-short, point-like source of epithermal neutrons using laser-driven ultra-short ion pulses would open new opportunities for many unprecedented time-resolved spectroscopic and imaging applications. This paper reports the first measurement of the ultra-short bursts of epithermal (sub-MeV) neutron beams using intense lasers, produced predominately by the endothermic 7Li(p,n)7Be reaction at the near energy threshold. Using a 6LiF scintillator in time-of-flight arrangement, epithermal neutrons of ∼ 107 n/sr/pulse in the range of 20-200 keV were measured, which intrinsically offers a beamed feature and ultra-short duration. The mechanism of epithermal neutron production and the crosscalibration of the diagnostic employed for extending the spectral measurements down to epithermal range are discussed.