E0041

NPDF: A New High-resolution Total Scattering Powder Diffractometer. Th. Proffen, Los Alamos National Laboratory, LANSCE-12, MS H805, Los Alamos, NM 87545.

Knowing the atomic structure of materials usually means determining the crystal structure. However, many modern materials are complex, and their real structure often is deviated locally from the average crystal structure in significant ways. It is thus necessary to know the structure on various length scales, since properties are more directly governed by local atomic arrangements. But the conventional crystallographic approach cannot provide a complete picture; it has to be complemented by local probes such as the Pair Distribution Function (PDF) method.

The Neutron Powder Diffractometer NPD has recently been upgraded to become NPDF by adding a large number of detectors to the backscattering region of the instrument. The upgrade was funded by the National Science Foundation, Los Alamos National Laboratory, University of Pennsylvania and other academic institutions. On September 27^th, 2002 the shutter of NPDF opened for the first time. A standard data set suitable for PDF analysis can be obtained in only two hours. This puts NPDF at the cutting edge of local structure determination but also serve as development platform for this new structure analysis tool for disordered and nano-structured materials. The instrument is available to general users in the 2003 run cycle.