[ Identification | Description | Input parameters | Output parameters | Links ]
Bragg_crystal
Component* Bragg_crystal.comp supercedes Perfect_Crystal.comp with major edits and corrections. * * For details see: * The optics of focusing bent-crystal monochromators on X-ray powder diffractometers with application to lattice parameter determination and microstructure analysis, * Marcus H. Mendenhall,* David Black and James P. Cline, J. Appl. Cryst. (2019). 52, https://doi.org/10.1107/S1600576719010951 * * Reads atomic formfactors from a data input file. * * The crystal code reflects ray in an ideal geometry, i.e. does not include surface imperfections or mosaicity. * The crystal planes from which the reflection is made lies in the X-Z plane on the unbent crystal rotated * by an angle alpha about the Y axis with respect to the crystal surface. * * The crystal itself is set in the X-Z plane positioned such that the long axis of the crystal surface coincides with * the Z-axis, with its normam pointing in the positve Y-direction. The angle between the Bragg planes and the crystal surface is alpha * * This code has been validated against both experimental data * (2 channel-cut 3-bounce Si 440 crystals together in non-dispersive mode, at Cu kalpha) * and against theoretical rocking rocking curves from XOP for Si220 at Sc kalpha and Si440 at Cu kalpha. * * Changelog: * - Off-axis rays fixed June 2015 so axial divergence corrections are right * - Inclusion of polarization and temperature dependence (via Debye-Waller factor), June-September 2015 * - Errors in complex arithmetic in DarwinReflectivity2 corrected, September 2015, MHM * - Symmetries for form factors corrected 20150924 * - Rotation code updated to use exact DarwinReflectivity Theta0, Thetah so answer is right even if alpha != 0. 20151009 MHM * - Results for (1,1,1) etc. with complex form factor made to agree with XOP. December 1st, 2016 * * Notation follows Tadashi Matsushita and Hiro-O Hashizume, X-RAY MONOCHROMATORS. Handbook on Synchrotron Radiation,North-Holland Publishing Company, 1:263–274, 1983. * * Non-copyright notice: * Contributed by the National Institute of Standards and Technology; not subject to copyright in the United States. * This is not an official contribution, in that the results are in no way certified by NIST. * *
Name | Unit | Description | Default |
length | 0.05 | ||
width | 0.02 | ||
V | 160.1826 | ||
form_factors | "FormFactors.txt" | ||
material | "Si.txt" | ||
alpha | 0.0 | ||
R0 | 0 | ||
debye_waller_B | 0.4632 | ||
crystal_type | 1 | ||
h | 1 | ||
k | 1 | ||
l | 1 | ||
structure_factor_scale_r | 0.0 | ||
structure_factor_scale_i | 0.0 |
Name | Unit | Description | Default |
prms |
Bragg_crystal.comp
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[ Identification | Description | Input parameters | Output parameters | Links ]
Generated on 2021-08-13 08:57:53