Science Subfields

From DANSE

Neutron scattering research is organized into subfields specializing in different types of science, approximately clustered around instruments that perform particular types of measurements. To best accommodate the needs of these subfields, the development of scientific software follows a similar decomposition into subfields:

Figure: Illustrating how the atomic Pair distribution function (PDF), derived from neutron diffraction data, yields local structural information from nanoparticles. Left: Packing of C60 "buckeyballs" into an fcc structure. Right: PDF obtained from a neutron diffraction experiment on such fcc C60. Note that the PDF peaks below the dashed line are spatially well-defined since they originate from pairs of atoms within one ball. The "peaks" beyond the dashed line correspond to atom-pairs in different balls. The balls are undergoing rotational motion at the temperature of measurement (RT) and this orientational disorder smears out the PDF peaks. The broad maxima around 10, 14 and 17 A come from the fcc arrangement of the balls.

• Diffraction. This method has the largest user community. Experiments includes studies of crystal structure and microstructure, both on liquids and amorphous materials, polycrystalline materials and single crystals (e.g., crystallography).

• Engineering Diffraction. Research in this field includes measurements and interpretations of internal strains in materials, and studies of crystalline textures in polycrystallie materials.

• Small-Angle Neutron Scattering (SANS). Users in this field have interests that span from biochemistry to solid-state magnetism. SANS research includes a large activity in polymer structure, and the structural evolution of polymers under temperature and flow.

• Reflectometry, which measures the depth profile of neutron scattering near a surface. The science includes structures of large molecules at surfaces and interfaces, and surface magnetism probed with polarized neutrons.

• Inelastic scattering, which studies dynamical processes such as the elementary excitations of phonons and magnons in solids, and vibrations and motions of molecules.

Diffraction (0.4 MB Powerpoint summary nugget) (http://wiki.cacr.caltech.edu/danse/images/f/f4/DANSE_DreamDesktop.ppt)

Engineering Diffraction (0.3 MB Powerpoint summary nugget) (http://wiki.cacr.caltech.edu/danse/images/b/bd/DANSE_EngND.ppt)

Small-Angle Scattering (0.4 MB Powerpoint summary nugget) (http://wiki.cacr.caltech.edu/danse/images/6/6a/DANSE_SANS.ppt)

Reflectometry (0.8 MB Powerpoint summary nugget) (http://wiki.cacr.caltech.edu/danse/images/1/1d/DANSE_Reflectometry.ppt)

Inelastic Scattering (0.3 MB Powerpoint summary nugget) (http://wiki.cacr.caltech.edu/danse/images/6/6d/DANSE_Inelastic_demo.ppt)