[ Identification | Description | Input parameters | Links ]

The Monochromator_bent Component

A bent crystal monochromator. Based on the model implemented by Jan Šaroun in NIMA 529 (2004) pp 162-165. Mosacity and bending radius can be set.

Identification

• Site:
• Author: Daniel Lomholt Christensen with help from Jan Šaroun
• Origin: ILL/NBI
• Date: 24 August 2023

Description

This monochromator is an array of crystals, that can be bent.
The crystals are placed by the user in the x,y,z pos and rot parameters.
The crystal is bent, so that it follows a curve on a cylinder of radius_x.
The monochromator lies along the z plane, so when a diffraction angle of theta
is desired, it should just be inserted in the ROTATED parameter around
the y-axis.
Instruments that showcase the use of this component is the
"Test_monochromator_bent.instr", and the "ILL_SALSA.instr" under the examples folder.
SALSA showcases its complex use in a real instrument, while Test_monochromator_bent
makes a simple show of its capabilities.

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
zwidth	m	Width of each crystal without bending.	0.2
yheight	m	Height of each crystal without bending.	0.1
xthickness	m	Thickness of each crystal without bending.	0.0005
radius_x	m	Radius of the circle the monochromator bends on in the plane. Can be negative.	2
radius_y	m	Radius of the (very large) circle the monochromator bends on as a side effect of the horizontal bending. The code assumes that it is so small that it does not affect the points of intersection appreciatively of the crystal.	0
plane_of_reflection	"Si400"	The plane of reflection from the material. The list of possible reflections can be seen in the source code.	"Si400"
angle_to_cut_horizontal	degrees	Angle between cut and normal of crystal slab, horizontally	0
mosaicity	arcmin	Gaussian mosaicity of the crystal. Always the horizontal mosaicity	30
mosaic_anisotropy	1	Anisotropy of the mosaicity, changes vertical mosaicity to be mosaic_anisotropy*mosaicity	1
n_crystals		[#] Number of crystals in your array.	1
domainthickness	mu-m	Thickness of the crystal domains.	10
temperature	K	Temperature of the monochromator in Kelvin.	300
optimize		Flag to tell if the component should optimize for reflections or not.	0
x_pos	vector	x-Position of each crystal	NULL
y_pos	vector	y-Position of each crystal	NULL
z_pos	vector	z-Position of each crystal	NULL
x_rot	vector	Rotation around x-axis for each crystal	NULL
y_rot	vector	Rotation around y-axis for each crystal	NULL
z_rot	vector	Rotation around z-axis for each crystal NOTE: Rotations happen around x, then y, then z.	NULL
verbose		Verbosity of the monochromator. Used for debugging.	0
draw_as_rectangles		Draw the monochromators as boxes. DOES NOT WORK WHEN USING _rot parameters.	0

AT (	,	,		) RELATIVE		Generate to clipboard
ROTATED (	,	,		) RELATIVE

Links

• Source code for Monochromator_bent.comp.
• Jan Šaroun NIM A Volume 529, Issue 1-3 (2004), pp162-165

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[ Identification | Description | Input parameters | Links ]

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Last Modified: Friday, 12-Dec-2025 12:58:06 CET