Generation of laser-induced fast neutrons and application for activation analysis

A laser-induced repetitively operated fast neutron source was developed by using a deuterated polystyrene film target and a femtosecond laser with a peak output power of approximately 24 TW and was applied for laser activation analyses of indium and gold samples. By using a home-made gated scintillation detector, the developed neutron source was estimated to have a neutron yield of approximately 4 × 10⁵ n/pulse at a pulse repetition rate of 5 Hz. For the neutron yield, relatively strong delayed gamma spectra were measured at 138 keV, 417 keV, 1097 keV, and 1294 keV for the activated indium, and at 333 keV and 355 keV for the activated gold. In addition to the delayed spectra, several prompt gamma spectra were measured during gold activation. These suggest possible uses of the neutron source for activation analysis of various materials.