Neutron Image Gallery: A Visual Guide to Neutron Imaging

X-rays and neutrons interact with materials differently, creating unique images. This rotary phone is comprised of many dense and light materials. The lower-energy 170 kV X-rays could not penetrate the denser materials of the phone. The higher-energy 440 kV X-rays could penetrate the denser materials, but was too high-energy to create an image of the lighter materials. The neutron beam could penetrate dense materials but not light materials, creating neutron radiograph that shows more detail of the phone’s inner workings than either X-ray image could on its own. The difference in how neutrons interact with light materials is what makes neutron radiography such a powerful complementary tool to X-ray radiography in materials science, materials research. and non-destructive testing applications.

Flowers tend to show up very distinctly on both neutron and X-ray images. However, water has a very high neutron scattering cross section, which makes neutron radiography and tomography useful for studying water uptake within root systems and rooted soil.

With examples such as this hand plane, it’s “plane” to see how neutron radiography and neutron images can show you details that can’t be seen with X-ray radiography. These three X-ray radiographs of varying energies, looked at as a whole, all together show almost as many details as a single neutron picture!

Like gadolinium, boron has an extremely large neutron cross section that makes it useful as a contrast agent in neutron imaging, among other things. In this example, welding flux, which contains large quantities of borax, attenuates neutrons particularly well compared to metals such as copper. This makes neutron imaging useful for assessing the quality of welds and making certain that undesirable remnants of flux do not remain on a welded part.

As with the images of the rotary phone, these fuel injectors depict the differences between high and low energy X-ray images as well as neutron imaging. The image taken with 100 kV X-rays misses important details regarding the fuel injectors’ structures because the X-rays cannot easily penetrate the dense outer layers of material. However, the image taken with 190 kV X-rays also misses important details because while the X-rays can pass more easily through the denser material, they also pass too easily through the lighter material as well. Neutron imaging, on the other hand, offers more detail than either of the X-ray radiography images on their own.

In particular, two of the fuel injectors have been clogged with contaminants (we used ketchup, butter, and mustard), which show up as white blockages in the plugs in the neutron image and do not show up at all in the X-ray images. This shows the value of neutron radiography and tomography in rooting out defective parts and other non-destructive testing applications!