STANDARD PROJECT FOR POLE-FIGURE DETERMINATION BY NEUTRON-DIFFRACTION

In an effort to evaluate the reliability of pole-figure measurements, a sample of experimentally deformed polycrystalline calcite was circulated among nine neutron diffraction facilities. This report compares results of the project both in terms of experimental pole figures and three-dimensional orientation distributions. In general textures agree very closely. For pole figures with strong diffraction intensities, standard deviations from the mean are 0.04-0.06 m.r.d. (multiples of a random distribution) with a spread of maxima values of 0.18 m.r.d. The spread is considerably larger for pole figures with weak diffraction intensities (0.37 m.r.d. for 110) and so are standard deviations (0.20 m.r.d.). For weak diffraction peaks one-dimensional position-sensitive detectors have an advantage over single-tube detectors. Two-dimensional position-sensitive detectors combined with time of flight (TOF) offer new possibilities but data processing needs to be improved. Greater care must be devoted to angle conventions: four of nine pole figures were inverted. This study can provide a basis for quantitative texture analysis and estimation of experimental uncertainties.