Browsing by Author "Ashkar, R"

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    Dynamical theory calculations of spin-echo resolved grazing-incidence scattering from a diffraction grating
    (Wiley-Blackwell, 2010-06-01) Ashkar, R; Stonaha, P; Washington, AL; Shah, VR; Fitzsimmons, MR; Maranville, B; Majkrzak, CF; Lee, WT; Schaich, WL; Pynn, R
    Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous wave source. In both cases, the spin-echo polarization, studied as a function of the spin-echo length, peaks at integer multiples of the grating period but there are some differences between the two sets of data. The dynamical theory explains the differences and gives a good account of both sets of results. © 2010, Wiley-Blackwell.