Neutron Small Angle Scattering is a non-destructive method for determination of microstructures with lengths between 0,5 nm and 500 nm. It is based on the principle that an initially parallel neutron beam is scattered by inhomogeneities of a sample. These can be due to fluctuations in density, concentration or magnetisation. This method is widely used in biological structure research (viruses, proteins, enzymes), polymer research (conformation analysis), energy and environmental engineering (porosity and surfaces of filter materials and catalysts) and the development of materials. Since the scattering length densities of the elementary volumes can readily be influenced for neutrons by modifying the isotopic composition of the sample, this technique ("contrast variation") has largely determined the success of small-angle neutron scattering in the fields of soft matter and biological structures.



Source: GKSS, SANS-2

There are three variants of small angle diffraction: pin hole small angle diffraction, double-crystal diffraction and focussing small angle diffraction. Of those double-crystal diffraction, which uses two silicon crystals as reflectors, allows for the highest resolution. Most small angle instruments are pin hole instruments, which have apertures that determine the size of the neutron beam. The focussing small angle scattering is a further development. Here, a mirror is used to focus the beam.