Neutron radiography, or N-ray, is a powerful nondestructive testing method due to the unique properties of neutrons. While the mechanics are similar, N-ray provides a new perspective compared to X-ray due to the different penetration depth of each type of radiation for different materials. While neutron radiography has been underutilized for non-destructive testing and materials research applications due to a lack of access to a powerful enough neutron source, Phoenix’s high flux neutron generators are changing the landscape.

See what new perspectives neutron radiography can offer you:

Beretta 92FS Neutron/X-Ray Image Comparison

X-Ray Image: Beretta 92FS Handgun
440kV X-ray imaging
Neutron Image: Beretta 92FS Handgun
Neutron imaging

Neutron radiography is especially useful for imaging munitions. In this neutron image, neutrons interact with parts within the firearm and show details that a high-energy x-ray would not depict, even the presence and position of gunpowder in the cartridge.

Rotary Telephone X-Ray/Neutron Image Comparison

X-Ray Image of a Rotary Phone
170kV X-ray imaging
X-Ray Image of a Rotary Phone
440kV X-ray imaging
Neutron Image of a Rotary Phone
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-ray beam could not penetrate the denser materials of the phone. The higher-energy 440 kV X-ray beam 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 an image that shows more detail of the phone’s inner workings than either X-ray image could on its own. This is what makes neutron radiography such a powerful complementary tool to X-ray radiography in materials science, materials research. and non-destructive testing applications.

Hand Plane X-Ray/Neutron Image Comparison

60kV X-Ray Image: Hand Planer
60kV X-ray imaging
140kV X-Ray Image: Hand Planer
140kV X-ray imaging
200kV X-Ray Image: Hand Planer
200kV X-ray imaging
Neutron Image: Hand Planer
Neutron imaging

With examples such as this hand plane, it’s “plane” to see how 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!

Fuel Injector X-Ray/Neutron Imaging Comparison

100kV X-Ray Image: Fuel Injectors
100kV X-ray image
190kV X-Ray Image: Fuel Injectors
190kV X-ray image
Neutron Image: Fuel Injectors
Neutron image

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 condiments, which show up as white blockages in the plugs in the N-ray image and do not show up at all in the X-ray images. This shows the value of neutron radiography in rooting out defective parts and other non-destructive testing applications!

Interactive N-Ray/X-Ray Comparison

100kV X-Ray Image: Fuel Injectors Neutron Image: Fuel Injectors
190kV X-Ray Image: Fuel Injectors Neutron Image: Fuel Injectors

Click and drag on the vertical line to compare X-ray radiography and neutron radiography images. One advantage neutron imaging offers over the X-ray images is that details that did not show up on either the high-energy or low-energy X-rays, such as blockages within the fuel injectors, are visible.

Proxivision Ball Bearings X-Ray/Neutron Imaging Comparison

225kV X-Ray Image: Ball Bearings
225kV X-ray image
400kV X-Ray Image: Ball Bearings
400kV X-ray image
Neutron Image: Ball Bearings
Neutron image

Interactive N-Ray/X-Ray Comparison

225kV X-Ray Image: Ball Bearings Neutron Image: Ball Bearings

Click and drag on the vertical line to compare X-ray and N-ray images.

Ejection Seat Handle X-Ray/Neutron Comparison

X-ray image: Ejection seat handles. Differences in color between the X-ray and N-ray image show how certain materials are more or less opaque to neutrons as they are to X-rays. In particular, details such as the springs are much more distinct in the N-ray image.
X-ray image
Neutron image: Ejection seat handles. Differences in color between the X-ray and N-ray image show how certain materials are more or less opaque to neutrons as they are to X-rays. In particular, details such as the springs are much more distinct in the N-ray image.
Neutron image

The components of ejection mechanisms, especially those containing energetic material, are especially receptive to neutron imaging, as the light and hydrogen-rich energetic material within the metal shell can be easily filmed with neutrons but not with X-rays. These ejection seat handles, which contain spring-loaded mechanisms designed to trigger those energetic devices, also reveal the key differences between X-ray and neutron radiography.

While both the neutron and X-ray image of the ejection seat handle depict many of the same details of the inner mechanisms, the uniformity of the materials can be seen in the lower contrast of the handle’s components in the X-ray image. This shows that many of the materials are of similar density. However, the neutron image of the ejection seat handle shows a much higher contrast between different parts of the handle since neutrons do not attenuate linearly with density and even very similar materials (elements close to each other on the periodic table, for example) can look quite different from each other in a neutron image.

Interactive N-Ray/X-Ray Comparison

Neutron image: Ejection seat handles. Differences in color between the X-ray and N-ray image show how certain materials are more or less opaque to neutrons as they are to X-rays. In particular, details such as the springs are much more distinct in the N-ray image. X-ray image: Ejection seat handles. Differences in color between the X-ray and N-ray image show how certain materials are more or less opaque to neutrons as they are to X-rays. In particular, details such as the springs are much more distinct in the N-ray image.

Click and drag on the vertical line to compare X-ray and N-ray images.

Aircraft Turbine Blade (Cross-Section)

Neutron Image: Aircraft Turbine Blade

This cross section of a jet engine turbine blade shows off one of the most useful and unique applications of industrial neutron radiography. Turbine blades are cast around ceramic molds, and fragments of ceramic can clog their vital cooling channels. A blade with clogged cooling channels could break or even melt while in operation, so such flaws must be rooted out with 100% certainty. The only way to reliably detect these ceramic fragments is to wash the blade in a solution containing gadolinium, an element with a high neutron cross section. Once the gadolinium has permeated the ceramic’s porous structure, the fragments will show up in stark contrast on the resulting neutron image.

Hard Disk Drives

Neutron Image: Hard Drives

Because of the way neutrons pass easily through denser metals, the neutron image of the 3.5″ hard disk drive on the left mainly shows the less dense plastic components of the hard drive’s internals. the 2.5″ external hard drive on the right is entirely encased in a plastic shell which is more opaque, but not entirely opaque, to neutrons.

Interactive N-Ray/X-Ray Comparison

X-Ray Image: Hard Drive Neutron Image: Hard Drive

Click and drag on the vertical line to compare X-ray and N-ray imaging. To neutrons, most of the metal parts of the hard disk drive, such as the faceplate, the read/write heads, and the disks themselves, are completely transparent, allowing a clearer look at some components that are not as visible, if at all, in the X-ray image.

Bats

Neutron Image: A set of bats imaged using neutron radiography. Unlike X-rays, neutrons are attenuated heavily by flesh and muscle, giving a unique perspective.

We’re batty for neutron radiography at Phoenix! Unlike X-rays, neutrons are attenuated heavily by flesh and muscle, giving a unique perspective to the radiographic image of these bat specimens. That is one of several reasons why your dentist probably isn’t interested in shooting neutron radiation at your teeth during your dental check-up.

Consumer Electronics

Neutron Image: Headphones
Neutron Image: Calculator

Neutron radiography can provide an interesting look into consumer electronics. As in the hard drive images, the plastic tends to be more opaque to neutrons in the neutron beam than most of the electronic components, providing a unique view of the structures of these items.

Personal Safe X-Ray/Neutron Imaging Comparison

A Honeywell safe used to test neutron and X-ray imaging
Photograph
X-ray image: A Honeywell safe captured in an X-ray radiograph.
X-ray image
Neutron image: A Honeywell safe captured in a neutron radiograph. The neutron radiation captures the plastic elements of the safe on film much more clearly than the X-rays do.
Neutron image
Neutron image: A Honeywell safe captured in a neutron radiograph. This close-up shows how neutron imaging was even able to capture the Honeywell logo on the front of the safe.

Your secrets aren’t safe from X-ray vision or neutron vision, but both forms of radiography show quite different perspectives in these images. Plastic components, which are rich in hydrogen, are particularly opaque on the neutron images but much more transparent on the X-ray images due to the high neutron attenuation of plastics and other hydrogen compounds. A closeup of the Honeywell safe shows that neutron imaging could even pick up on the details of the embossed logo on the door to the safe!

Flashlight X-Ray/Neutron Imaging Comparison

Neutron Image: Flashlight
Neutron image
X-Ray Image: Flashlight
X-ray image

Both neutron radiography and X-ray radiography can offer distinct advantages over each other. In these images, both depict unique features of the flashlight in question. Phoenix is currently working on a method to seamlessly combine the data from X-ray and neutron imaging together into hybrid images, which would allow for an unparalleled look into an object’s inner working for cases in which both X-ray radiography and neutron radiography provide indispensable data.

Jar of Staples

X-Ray Image: Jar of Staples with Toy Neutron Image: Jar of Staples with Toy

Click and drag on the vertical line to compare X-ray and neutron imaging. For a rather offbeat comparison of the strengths and weaknesses of X-ray and neutron imaging, we filled a glass jar with staples and a single plastic figurine. In the X-ray image, only the staples are visible. With neutron imaging, the staples are far less visible, but the figurine hidden within is entirely visible as the neutrons interact more heavily with the plastic.

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