In this chapter, the potential and limitations of neutron imaging methods for the research into cultural heritage objects will be demonstrated on the example of investigations carried out at the neutron imaging facilities of the Paul Scherrer Institute. The working principles of neutron imaging and differences to conventional X-ray imaging studies are explained and illustrated on practical examples. Often, neutron and X-ray imaging methods can be used in complementary or even synergetic manner (data fusion).
In some cases, a simple radiography inspection is enough to answer questions or to verify hidden features. In other cases, it is necessary to perform neutron tomography for the understanding of an object by verification of the volumetric material distributions. By means of virtual slices and digital segmentations, it is often possible to derive the size, distribution, and structure of the inner components of an archaeological artifact shedding new light on the studied objects.
Neutron imaging has much higher penetration ability for heavy elements, in particular precious metals (e.g., Au, Ag, Pt) but also for the components of widely used metal alloys such as bronze or brass (Cu, Zn, Sn, Pb). At the same time, neutrons show high sensitivity for some light elements, in particular for hydrogen, which is of special interest as it is an element present as well in organic material as well as in many corrosion products. This complementary behavior makes it a unique method to investigate organic material or the corrosion within metal objects. The latter can be used to characterize the status of corroded artifacts and to plan and verify their conservation and protection process.