Fig. 1. Design of the experimental setup for the generation of an ultra-short pulsed neutron source and the fast neutron absorption spectroscopy.

Fig. 2. Three-dimensional particle-in-cell simulations of laser plasma acceleration. (a)–(d) represent four different times at 0.25, 0.5, 0.75 and 1 ps, respectively. The nitrogen atom density is and the laser = 2.

Fig. 3. Simulation results of the electron beam. (a) Variation of electron beam charge ( > 1 MeV) with the nitrogen atom density. (b) Electron energy spectra for different nitrogen atom densities.

Fig. 4. Simulation results of the Bremsstrahlung source driven by the laser plasma electron accelerator. (a) -ray spectrum (red line) photo-nuclear reactions of , and Ta. (b) -ray source transversal distribution, which is detected on the plane of the rear surface of the Ta converter.

Fig. 5. Simulation results of the neutron source driven by the laser plasma electron accelerator. (a) Neutron spatial distribution. (b) Neutron angular distribution. (c) Neutron energy spectrum. (d) Neutron yield and pulse duration.

Fig. 6. Single-neutron-count fast neutron absorption spectroscopy. (a) Transmissivities for two materials, that is, graphite and TNT. (b)–(d) Simulated neutron absorption spectrum for the pulse duration of 36 ps, where the total neutron counts are (b), (c) and (d), respectively. (e) Absorption spectrum for the pulse duration of 1 ns, where the total count is .