The principle of neutron transmission radiography is identical to X-ray radiography
: the intensity of neutron beam is attenuated by the object material and then recorded by a neutron sensitive imaging detector.
Thanks to different values of neutron and X-ray attenuation coefficients in matter, neutron radiography can visualize structures which can be hardly distinguished with X-rays (e.g. light elements such as Hydrogen or Carbon in plastic or biological samples).
Adapting a pixel detector (Medipix
) for detection of slow neutrons requires the use of a suitable neutron converter material. Converter material captures slow neutrons and produces secondary radiation which can be detected by the sensor chip. The range of secondary radiation in the sensor should be short to conserve high spatial resolution. Materials containing 6Li or 10B are well suited from this point of view as they convert neutrons to heavy charged particles.