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10.6 The Divergence_monitor McStas Component
Horizontal+vertical divergence monitor.
Identification
-
Author: Kim Lefmann
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Origin: Risoe
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Date: Nov. 11, 1998
Description
A divergence sensitive monitor. The counts are distributed in (n times m) pixels.
Example: Divergence_monitor(nh=20, nv=20, filename="Output.pos",
xmin=-0.1, xmax=0.1, ymin=-0.1, ymax=0.1,
maxdiv_h=2, maxdiv_v=2)
Input parameters
Parameters in boldface are required; the others are optional.
|
Name |
Unit |
Description |
Default |
|
|
|||
|
nh |
1 |
Number of pixel rows |
20 |
|
nv |
1 |
Number of pixel columns |
20 |
|
filename |
str |
Name of file in which to store the detector image text |
0 |
|
xmin |
m |
Lower x bound of detector opening |
-0.05 |
|
xmax |
m |
Upper x bound of detector opening |
0.05 |
|
ymin |
m |
Lower y bound of detector opening |
-0.05 |
|
ymax |
m |
Upper y bound of detector opening |
0.05 |
|
nowritefile |
1 |
If set, monitor will skip writing to disk |
0 |
|
xwidth |
m |
Width of detector. Overrides xmin, xmax |
0 |
|
yheight |
m |
Height of detector. Overrides ymin, ymax |
0 |
|
maxdiv_h |
degrees |
Maximal vertical divergence detected |
2 |
|
maxdiv_v |
degrees |
Maximal vertical divergence detected |
2 |
|
restore_neutron |
1 |
If set, the monitor does not influence the neutron state |
0 |
|
nx |
1 |
x-component of the "forward" direction vector (see ny) |
0 |
|
ny |
1 |
Vector definition of "forward" direction wrt. divergence, to be used e.g. when the monitor is rotated into the horizontal plane |
0 |
|
nz |
1 |
z-component of the "forward" direction vector (see ny) |
1 |
|
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Links
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Component source code found in file Divergence_monitor.comp.
A divergence sensitive monitor
The component Divergence_monitor is a two-dimensional monitor, which resembles PSD_Monitor. As for this component, the detector window is set by the \(x\) and \(y\) input coordinates. Divergence_ monitor is sensitive to the neutron divergence, defined by \(\eta _\textrm {h} = \tan ^{-1}(v_x/v_z)\) and \(\eta _\textrm {v} = \tan ^{-1}(v_y/v_z)\). The neutron counts are being histogrammed into \(n_\textrm {v} \times n_\textrm {h}\) pixels. The divergence range accepted is in the vertical direction \([-\eta _\textrm {v,max}; \eta _\textrm {v,max}]\), and similar for the horizontal direction.
The output from PSD_monitor is the integrated counts, \(n, I, M_2\), as well as three two-dimensional arrays of counts: \(n(\eta _\textrm {v},\eta _\textrm {h}), I(\eta _\textrm {v},\eta _\textrm {h}), M_2(\eta _\textrm {v},\eta _\textrm {h})\). The arrays are written to a file, filename, and can be read e.g. by the tool MC_plot, see the system manual.
