But neutrons have some unsung properties that make them useful for investigating matter. Because they are neutral, they can penetrate deeper into a sample than electrons can. Because they have mass and spin, they have a magnetic moment and can probe magnetism. Because they interact with nuclei rather than electron orbitals, they are sensitive to light elements and can even distinguish between hydrogen and deuterium. And they're nondestructive. These features are inspiring researchers to use neutrons to analyze a variety of materials, from coal and complex fluids to cell membranes and membrane proteins and including magnetic materials.
The inelastic neutron scattering probe has, since the early days of high-Tc superconductors, provided most of the evidence for the magnetic resonance peak for the Cu-oxide plane. So just in material science alone, this has been an extremely important technique. The Spallation Neutron Source at Oak Ridge, when it comes online, will be one powerful facility to study a whole zoo of things.