[ Identification | Description | Input parameters | Links ]

The Monochromator_2foc Component

Double bent monochromator with multiple slabs

Identification

• Site:
• Author: Peter Link.
• Origin: Uni. Gottingen (Germany)
• Date: Feb. 12,1999

Description

Double bent monochromator which uses a small-mosaicity approximation as well
as the approximation vy^2 << vz^2 + vx^2.
Second order scattering is neglected.
For an unrotated monochromator component, the crystal plane lies in the y-z
plane (ie. parallel to the beam).
When curvatures are set to 0, the monochromator is flat.
The curvatures approximation for parallel beam focusing to distance L, with
monochromator rotation angle A1 are:
RV = 2*L*sin(DEG2RAD*A1);
RH = 2*L/sin(DEG2RAD*A1);

Example: Monochromator_2foc(zwidth=0.02, yheight=0.02, gap=0.0005, NH=11, NV=11,
mosaich=30, mosaicv=30, r0=0.7, Q=1.8734)

Example values for lattice parameters
PG       002 DM=3.355 AA (Highly Oriented Pyrolytic Graphite)
PG       004 DM=1.607 AA
Heusler  111 DM=3.362 AA (Cu2MnAl)
CoFe         DM=1.771 AA (Co0.92Fe0.08)b
Ge       311 DM=1.714 AA
Si       111 DM=3.135 AA
Cu       111 DM=2.087 AA
Cu       002 DM=1.807 AA
Cu       220 DM=1.278 AA
Cu       111 DM=2.095 AA

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
reflect	k, R	reflectivity file name of text file as 2 columns	0
zwidth	m	horizontal width of an individual slab	0.01
yheight	m	vertical height of an individual slab	0.01
gap	m	typical gap between adjacent slabs	0.0005
NH	columns	number of slabs horizontal	11
NV	rows	number of slabs vertical	11
mosaich		Horisontal mosaic FWHM (arc minutes)	30.0
mosaicv		Vertical mosaic FWHM (arc minutes)	30.0
r0	1	Maximum reflectivity	0.7
Q	AA-1	Scattering vector	1.8734
RV	m	radius of vertical focussing, flat for 0	0
RH	m	radius of horizontal focussing, flat for 0	0
DM	Angstrom	monochromator d-spacing instead of Q=2*pi/DM	0
mosaic		sets mosaich=mosaicv (arc minutes)	0
width	m	total width of monochromator	0
height	m	total height of monochromator	0
verbose	0/1	verbosity level	0

AT (	,	,		) RELATIVE		Generate
ROTATED (	,	,		) RELATIVE

Links

• Source code for Monochromator_2foc.comp.
• Additional note from Peter Link.

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[ Identification | Description | Input parameters | Links ]

Generated on 2023-09-19 20:01:36

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Last Modified: Tuesday, 16-Apr-2024 20:05:20 CEST