The Complementarity Of X Rays And Neutrons

Nature is subtle and grudgingly reveals her secrets. In such an uneven contest scientists need to exploit every possible advantage. Just as high energy and nuclear physicists use hadrons, leptons and photons as scattering probes, so the modern condensed matter scientists relies upon NMR, ESR, [mu]SR, infrared, optical and UV spectroscopy as well as classical transport and thermal measurements, to understand material properties. For structural studies electron and x-ray diffraction are commonly used. Traditionally neutrons, because of the expense and the potential for greater environmental impact associated with their production, are reserved for studies where their unique properties mandate their use. The emergence throughout the world of major user facilities for both synchrotron x-rays and neutrons has recently underlined the degree to which x-ray and neutron scattering studies complement one another. Let us quickly review some of the advantages of neutrons. Neutrons are more penetrating, more precise (to the extent that they scatter from the nucleus rather than the extended electron cloud), more uniform in scattering power, more magnetic'' and more massive (and thus less energetic) than x-rays of comparable wavelength. Indeed, if expense and ease of access were not a factor, neutrons would very often be the probe of choice. This report discusses some of these properties of neutrons and how they complement x-ray diffraction in condensed matter studies. (LSP).