Neutron imaging

Neutron imaging is the process of making an image with neutrons. The resulting image is based on the neutron attenuation properties of the imaged object. The resulting images have much in common with industrial X-ray images, but since the image is based on neutron attenuating properties instead of X-ray attenuation properties, some things easily visible with neutron imaging may be very challenging or impossible to see with X-ray imaging techniques (and vice versa).
X-rays are attenuated based on a material's density. Denser materials will stop more X-rays. With neutrons, a material's likelihood of attenuation of neutrons is not related to its density. Some light materials such as boron will absorb neutrons while hydrogen will generally scatter neutrons, and many commonly used metals allow most neutrons to pass through them. This can make neutron imaging better suited in many instances than X-ray imaging; for example, looking at O-ring position and integrity inside of metal components, such as the segments joints of a Solid Rocket Booster.