Some fundamental considerations in resonance imaging using fast neutrons

Resonance imaging with mono-energetic (or quasi-mono-energetic) fast neutrons is able to map features in bulk samples in a way that is sensitive to their elemental composition. It has a number of potential applications, for example, in mining and in the detection of contraband substances such as drugs and explosives. The realisation of these applications depends on the availability of intense neutron sources with a narrow energy distribution and also the development of position-sensitive fast neutron detectors that have adequate efficiency and resolution. Both of these topics present many challenges for research in applied physics. Developments in the use of the reaction D(d,n)3He as an intense, accelerator-based source of neutrons with a reasonably small energy spread over a wide energy range will be described. In addition, the physics of neutron detection will be discussed in relation to resolution and efficiency using position-sensitive detectors based on a proton radiator and a scintillator. In this case, both the use of image intensifiers coupled to CCDs as well as the use of TFT imaging screens (for example as developed by Varian) will be described. These will be contrasted with recent developments using channel plates.