Fast neutrons were generated from a deuterated polystyrene (C8D8) solid target by using an ultraintense Ti:sapphire laser with a 27-fs pulse width and a 260-mJ pulse energy. The dependency of neutron generation on the amplified spontaneous emission (ASE) width was analyzed in terms of the deuteron energy. At a shorter ASE width of 1 ns, neutron tracks of the 3533/pulse were obtained for a target thickness of 80 µm. In addition, the time-of-flight (TOF) neutron signal was analyzed in terms of the X-ray and the neutron signals.

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A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma.