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McStas: Monochromator_2foc

[ Identification | Description | Input parameters | Links ]

The Monochromator_2foc Component

Double bent monochromator with multiple slabs


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


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.
reflectk, Rreflectivity file name of text file as 2 columns0
zwidthmhorizontal width of an individual slab0.01
yheightmvertical height of an individual slab0.01
gapmtypical gap between adjacent slabs0.0005
NHcolumnsnumber of slabs horizontal11
NVrowsnumber of slabs vertical11
mosaichHorisontal mosaic FWHM (arc minutes)30.0
mosaicvVertical mosaic FWHM (arc minutes)30.0
r01Maximum reflectivity0.7
QAA-1Scattering vector1.8734
RVmradius of vertical focussing, flat for 00
RHmradius of horizontal focussing, flat for 00
DMAngstrommonochromator d-spacing instead of Q=2*pi/DM0
mosaicsets mosaich=mosaicv (arc minutes)0
widthmtotal width of monochromator0
heightmtotal height of monochromator0
verbose0/1verbosity level0


[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43

Last Modified: Tuesday, 16-Apr-2024 20:05:21 CEST
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