Development of fast neutron profiling method

We discuss the effects of neutron scattering and γ-ray background in fast neutron imaging and the method to reduce them. As a profiling device, a combination of an imaging plate (IP) and a polypropylene film (CH₂) has been employed in this study. Good profiles were obtained by employing appropriate neutron energy, a CH₂ thickness and geometry for accelerator-based fast neutrons (5–14 MeV). The neutron flux was ∼3.5×10⁴ cm⁻² s⁻¹ in the CH₂–IP position. Furthermore, we are designing the device using a position-sensitive photomultiplier in order to improve the signal-to-noise ratio by obtaining the information of pulse height for particle selection together with position.