Component implementing a true incoherent scattering process
Author: Mads Bertelsen and Erik B Knudsen
Origin: ESS DMSC & DTU Physics
Date: 20.08.15
This Union_process is based on the Incoherent.comp component originally written by Kim Lefmann and Kristian Nielsen.
Part of the Union components, a set of components that work together and thus separates geometry and physics within McXtrace. The use of this component requires other components to be used.
1) One specifies a number of processes using process components like this one 2) These are gathered into material definitions using Union_make_material 3) Geometries are placed using Union_box / Union_cylinder, assigned a material 4) A Union_master component placed after all of the above
Only in step 4 will any simulation happen, and per default all geometries defined before the master, but after the previous will be simulated here.
There is a dedicated manual available for the Union_components
Algorithm: This component is an approximation. It scatters completely isotropically.
Parameters in boldface are required; the others are optional.
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Name |
Unit |
Description |
Default |
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sigma |
barns |
Incoherent scattering cross section |
5.08 |
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f_QE |
1 |
Fraction of quasielastic scattering (rest is elastic) |
0 |
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gamma |
1 |
Lorentzian width of quasielastic broadening (HWHM) |
0 |
|
packing_factor |
1 |
How dense is the material compared to optimal 0-1 |
1 |
|
unit_cell_volume |
Å\(^{3}\) |
Unit_cell_volume |
13.8 |
|
interact_fraction |
1 |
How large a part of the scattering events should use this process 0-1 (sum of all processes in material = 1) |
-1 |
|
init |
string |
Deprecated and unused. Accepted so that instruments written for McStas/McXtrace 3.8.7 and earlier, which name the Union_init component here, still compile. |
”” |
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Component source code found in file Incoherent_process.comp.
The test/example instrument Test_Phonon.instr.