X-ray or neutron imaging?

X-rays imaging is generally the first choice for examination of museum objects for their availability and easy application. But where X-rays fail or cannot deliver specific information, such in case of dense materials like bulky metals, neutron imaging methods will be successful at most times, delivering contrasts and penetration data that are not accessible for X-rays. Neutrons also deliver contrast between many neighbouring elements in the periodic system, often rendering contrast between very similar materials. In addition, neutron imaging provides high contrast for hydrogen containing phases, which can be easily located even in the presence of heavy atoms.