Release: McStas 1.6
This components may either set the flux or change it (filter-like), using an external data filename.
Author: E. Farhi
Origin: ILL
Date: Dec, 15th, 2002
This component changes the neutron flux (weight) in order to match a reference table in a filename. Typically you may set the neutron flux (source-like), or multiply it using a transmission table (filter-like). The component may be placed after a source, in order to e.g. simulate a real source from a reference table, or used as a filter (BeO) or as a window (Al). The behaviour of the component is specified using the ’options’ parameter, or from the filename itself (see below) If the thickness for the transmission data filename D was t0, and a different thickness t1 would be required, then the resulting transmission is:
D^(t1/t0).
You may use the ’thickness’ and ’scaling’ parameter for that purpose.
File format: This filename may be of any 2-columns free format (k[Å-1],p), (omega[meV],p) and (lambda[Å],p) where p is the weight. The type of the filename may be written explicitely in the filename, as a comment, or using the ’options’ parameter. Non mumerical content in filename is treated as comment (e.g. lines starting with ’#’ character). A table rebinning and linear interpolation are performed.
EXAMPLE : in order to simulate a PG filter, using the lib/data/HOPG.trm file Filter_gen(xwidth=.1 yheight=.1, filename="HOPG.trm") A Sapphire filter, using the lib/data/Al2O3_sapphire.trm file Filter_gen(xwidth=.1 yheight=.1, filename="Al2O3_sapphire.trm") A Berylium filter, using the lib/data/Be.trm file Filter_gen(xwidth=.1 yheight=.1, filename="Be.trm") an other possibility to simulate a Be filter is to use the PowderN component: PowderN(xwidth=.1, yheight=.1, zdepth=.1, reflections="Be.laz", p_inc=1e-4)
in this filename, the comment line # wavevector multiply sets the behaviour of the component. One may as well have used options="wavevector multiply" in the component instance parameters.
Parameters in boldface are required; the others are optional.
|
Name |
Unit |
Description |
Default |
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filename |
str |
name of the filename to look at (first two columns data). Data D should rather be sorted (ascending order) and monotonic filename may contain options (see below) as comment |
0 |
|
options |
str |
string that can contain: "[ k p ]" or "wavevector" for filename type, "[ omega p]" or "energy", "[ lambda p ]" or "wavelength", "set" to set the weight according to the table,"multiply" to multiply (instead of set) the weight by factor,"add" to add to current flux,"verbose" to display additional informations. |
0 |
|
xmin |
m |
dimension of filter |
-0.05 |
|
xmax |
m |
dimension of filter |
0.05 |
|
ymin |
m |
dimension of filter |
-0.05 |
|
ymax |
m |
dimension of filter |
0.05 |
|
xwidth |
m |
Width/diameter of filter). Overrides xmin,xmax. |
0 |
|
yheight |
m |
Height of filter. Overrides ymin,ymax. |
0 |
|
thickness |
1 |
relative thickness. D = D^(thickness). |
1 |
|
scaling |
1 |
scaling factor. D = D*scaling. |
1 |
|
verbose |
1 |
Flag to select verbose output. |
0 |
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Component source code found in file Filter_gen.comp.
HOPG.trm filename as an example.