Texture analysis with the new HIPPO TOF diffractometer

The new neutron time-of-flight (TOF) diffractometer HIPPO (High-Pressure-Preferred Orientation) at LANSCE (Los Alamos Neutron Science Center) is described and results for quantitative texture analysis of a standard sample are discussed. HIPPO overcomes the problem of weak neutron scattering intensities by taking advantage of the improved source at LANSCE, a short flight path (9 m) and a novel three-dimensional arrangement of detector banks with 1360 He-3 tubes, on five conical rings with scattering angles ranging from 2theta = 10degrees to 150degrees. Flux at the sample is on the order of 10(7) neutrons cm(-2) s(-1). A large sample chamber (75 cm diameter well) can accommodate ancillary equipment such as an automatic sample changer/goniometer used in this study. This instrument was used to measure the texture of a round-robin limestone standard and extract orientation distribution data from TOF diffraction spectra with different methods (Rietveld harmonic method, Rietveld direct method, automatic fitting of individual peak intensities), and the results compare favorably. Also, there is good agreement with results obtained on the same sample measured at other facilities. but with greatly reduced measuring time for HIPPO. (C) 2003 Elsevier B.V. All rights reserved.