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Energy-Dispersive Neutron-Transmission Diffraction (EDNTD) (An alternative for steady state source) Pavol Mikula, NPI v.v.i. Řež. Energy-Dispersive Neutron-Transmission Diffraction. 2 d hkl sin hkl = hkl = =2 d hkl.
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Energy-Dispersive Neutron-Transmission Diffraction (EDNTD)(An alternative for steady state source)Pavol Mikula, NPI v.v.i. Řež
Energy-Dispersive Neutron-Transmission Diffraction 2dhklsin hkl=hkl==2dhkl Diffraction edge I() modulation Instrumental resolutiond/d=5.7x10-4
The resolution (the sensitivity to the Bragg edge shift due to the strain) depends on several parameters: • Thickness of the bent crystal monochromator (smaller thickness of the crystal, the resolution is higher, however, the luminosity of the instrument is lower) • Take-off angle of the monochromator (the larger take off angle, the resolution is higher) • The width of the slit in front of the sample • Spatial resolution of the 1d- position sensitive detector and/or the distance between the sample and the detector
EDNTD examples Bragg diffraction edge of a 8 mm thick sample. Sample thickness dependence of Ao FWHM=5.7x10-4 rad FWHM=12.5x10-4 rad
Energy-Dispersive Neutron-Transmission Diffraction low-carbon steel 0.22% C, 0.64% Mn, 0.41% Si, 0.035% P, 0.04% S(in wt.%) Fe (321) diffraction edges
Comparison of the EDNTD with the conventional Bragg-diffraction-angle analysis technique 110 reflection 1% strain 5% strain