Center for High Resolution Neutron Scattering (CHRNS)
The Center for High Resolution Neutron Scattering (CHRNS) is a joint NSF/NIST national user facility within NIST's Center for Neutron Research (NCNR) that develops and operates state-of-the-art neutron scattering instrumentation, with broad application in materials research, for use by the general scientific community. Over 250 scientists, postdoctoral fellows and graduate students use the CHRNS instruments each year.
The diffraction of neutrons from a crystalline sample furnishes information about the structural arrangement of the atoms that compose it. The high-resolution powder diffractometer is used to measure diffraction patterns from powder specimens suitable for crystallographic analysis by the Rietveld method. The residual stress diffractometer can be used for crystallographic measurements of single-crystal samples and for mapping stresses in engineered materials.
Reflectometry uses neutrons scattered at grazing angles from a flat specimen to probe the layer profile of various materials. Examples of materials studied include biological membranes, thin polymer films, and layered metallic materials. Application of polarized beams permits the determination of the magnetic, as well as nuclear, profiles of thin films.
Small Angle Neutron Scattering (SANS)
The small angle neutron scattering technique is a valuable method for the characterization of nanoscale structure of materials. NCNR's SANS instruments can probe inhomogeneties, both structural and magnetic, in the sample a length scale from 1nm to over 1000 nm.
The energy scale of neutrons (meV) makes them ideal probes of the dynamics of materials. The versatility of instrumentation at the NCNR enables measurements of dynamical properties over a wide range of energies. This allows determinations of many excitations in materials, from the vibrations, rotations, tunneling and diffusive motions of atoms, molecules, and macrmolecules, to the fundamental quantum mechanical excitations such as spin waves, lattice vibrations, and magnetic excitons.