[ Identification | Description | Input parameters | Output parameters | Links ]

The Bragg_crystal_bent Component

* * Bent, perfect, reflecting crystal with common cubic structures (diamond, fcc, or bcc, and others if symmetry form factor multipliers provided explicitly) * *

Identification

Description

* Bragg_crystal_bent.comp supercedes Perfect_Crystal_bent.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, 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 external geometry of the crystal follows that of Elliptic_mirror.comp.
* I.e. the crystal is positioned such that the a-axis of the ellipsoid is on the
* z-axis, the b-axis is along the y-axis and the c is along the x-axis.
* The reference point of the crystal is the ellipsoid centre, offset by one half-axis along the y-axis.
* (See the component manual for Elliptic_mirror for a drawing).
*
* 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.
*
* NOTE: elliptical coordinate code and documentation taken from Mirror_elliptic.comp distributed in McXtrace v1.2
* However, the coordinates are rotated to be consistent with Bragg_crystal_flat.comp and Perfect_Crystal.comp.
* Idealized elliptic mirror with surface ellipse and lattice ellipses independent, to allow construction of
* Johansson optics, for example.
*
*

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
x_a0
y_b1.0
z_c1.0
lattice_x_a0
lattice_y_b1.0
lattice_z_c1.0
length0.05
width0.02
V160.1826
form_factors"FormFactors.txt"
material"Si.txt"
alpha0.0
R00
debye_waller_B0.4632
crystal_type1
h1
k1
l1
structure_factor_scale_r0.0
structure_factor_scale_i0.0

Output parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
prms
a2inv
b2inv
c2inv
l_a2inv
l_b2inv
l_c2inv

Links


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated on 2021-08-13 08:57:53