Analysis and simulation of neutron diffraction patterns

Abstract

The analysis of neutron diffraction powder patterns and the simulation of single crystal oscillation patterns is described.
The main factors governing the position and intensity of the coherent diffraction peaks and the factors contributing to the
background level of scattered radiation in the diffraction pattern are discussed.
Computer programs are described which have been used to reduce the raw data producedby a multicounter powder diffractometer, such as the DIDO Curran instrwnent at AEBE, Harwell, into a single normalised count against angle; to detect peaks in the normalised data, to calculate their intensity and to separate the peaks from the background so that further analysis can be performed separately on the peaks and background of the pattern.
The locations of diffraction spots produced on a single crystal oscillation X ray or neutron di!ffraction photograph are
calculated and the pattern is simulated to asSist the interpretation of magnetic and chemical structures. Comparison is made with data obtained from the D12 neutron oscillation camera facility at the Institut Max Von Laue, Paul Langevin, Grenoble.