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Phase imaging using time‐of‐flight neutron diffraction
Author(s) -
Gutmann M. J.,
Kockelmann W.,
Chapon L. C.,
Radaelli P. G.
Publication year - 2006
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889805041580
Subject(s) - optics , diffraction , beamline , collimated light , neutron , bragg's law , physics , neutron diffraction , time of flight , scattering , offset (computer science) , materials science , beam (structure) , nuclear physics , laser , computer science , programming language
A technique that allows the spatial distribution of crystallographic phases in the interior of an object to be reconstructed from neutron time‐of‐flight (TOF) diffraction is described. To this end, the shift of the Bragg peaks due to the so‐called `geometrical aberration' is exploited. A collimated incident white beam is used to perform a translational or rotational scan of the object whilst collecting a TOF data set for each sample position or orientation. Depending on the location of any scattering material along the line of the incident beam path through the object, the measured d ‐spacings of the corresponding Bragg peaks are shifted with respect to their nominal values, which are attained only at the geometrical centre of the instrument. Using a formula that is usually employed to correct for sample offset, the phase distribution along the incident beamline can be directly reconstructed, without the need to perform a tomographic reconstruction. Results are shown from a demonstration experiment carried out on a cylindrical Al container enclosing an arrangement of Cu and Fe rods. On the basis of this formalism, an optimized experimental geometry is described and the potential and limits of this technique are explored, as are its applicability to X‐ray and constant‐wavelength neutron diffraction.