14.51  The Monochromator_2foc McStas Component

Double bent monochromator with multiple slabs

Identification

• Author: <a href="mailto:plink@physik.tu-muenchen.de">Peter Link</a>.

• 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 Å (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.

Links

• Component source code found in file Monochromator_2foc.comp.

• Additional note from Peter Link.