Do you know the difference between neutron imaging and X-ray imaging (such as when using CT or synchrotron)? Unlike X-rays, which rely on electrons and attenuate depending on the density of an object, neutron imaging, as its name suggests, relies on neutrons. This means that how an object is imaged is not related to its density (as in X-rays) but instead on the chemical composition of materials (and other neutron attenuation properties).
For example, while X-rays are good at imaging your (hard) bone within your arm (surrounded by soft muscles and skin), a neutron beam would not produce a similarly clear picture. However, often when trying to image really dense materials (such as metallic objects), X-rays fail to adequately penetrate. In contrast, using neutron imaging, materials that contain a lot of hydrogen (water, for example) will not image well but dense materials, such as many metals, allow the neutrons to pass through them and thus can be imaged.
Together with my colleagues, Prof. Kate Trinajstic and Prof. John Long, I visited the OPAL reactor run by the Australian Nuclear Science and Technology Organisation (ANSTO) last month to image a spectacular specimen of the tetrapodomorph fish, Gogonasus. We believe we have the entire fish contained within one large “Gogo nodule” but wanted to avoid preparing it in the traditional way (using weak acetic acid to dissolve the limestone) in case there was preserved soft tissue inside.
We used the Neutron Imaging instrument, Dingo, and worked with instrument scientist, Dr Joseph Bevitt to scan this 375 million-year-old fossil fish. Having already imaged the same specimen using micro-CT and synchrotron imaging at the ESRF last year, this will provide a great study to compare the different methods.