What Are Neutrons Needed For

If you want to see an object, you have to illuminate it. If you want to discern details of an object, you will have to illuminate it with "light" of a wavelength equal to or smaller than the distance between the object details you are interested in. For most solids (or condensed media), such details of interest to physicists (for example, lattice sites, liquids, colloids, plastics, polymer and biological materials, etc.) lie from a few angstroms (10 cm) to tens nanometers distance from one another. This means that the "light" required for studying the such structures should have a wavelength of the same order. Such light does exist. It is Xand gamma rays, as well as beams of elementary particles, for instance, neutrons.