Dynamical theory calculations of spin-echo resolved grazing-incidence scattering from a diffraction grating

Authors

Rana Ashkar, Indiana University - BloomingtonFollow
P. Stonaha, Indiana University - Bloomington
A. L. Washington, Indiana University - Bloomington
V. R. Shah, University of Nebraska - Lincoln
M. R. Fitzsimmons, Los Alamos Neutron Science Center
B. Maranville, NIST Center for Neutron Research, Gaithersburg, MD
C. F. Majkrzak, NIST Center for Neutron Research, Gaithersburg, MD
W. T. Lee, Bragg Institute, Australian Nuclear Science and Technology Organization
W. L. Schaich, Indiana University
Roger Pynn, Indiana UniversityFollow

Date of this Version

2010

Citation

J. Appl. Cryst. (2010). 43, 455–465

doi:10.1107/S0021889810010642

Comments

(c) 2010 International Union of Crystallography. Used by permission.

Abstract

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.