Numerical neutron attenuation correction for partially-illuminated powder samples

Abstract

Chemical phase quantification from neutron diffraction measurements relies on accurate Bragg peak intensities at all diffraction angles. Amongst others these intensities are influenced by the total distance that the neutron beam has traversed through the sample in reaching the contributing volume segment and the distance from the contributing volume segment to the outer edge of the sample in the direction of the neutron detector. Since the total path length is dependent on the diffraction angle, gauge volume position inside the sample, as well as the sample dimensions and shape, the measured diffraction pattern should be corrected to account for this non-constant attenuation effect. Results show that in highly attenuation materials this can influence refined parameters during chemical phase quantification. A module was designed and integrated into the data reduction system ScanManipulator used at the neutron diffraction facility at the SAFARI-1 research reactor. The correction technique can further be used to accurately determine diffraction patterns obtained from position-resolved neutron diffraction experiments.