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10.1 The TOF_monitor McStas Component
Rectangular Time-of-flight monitor.
Identification
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Author: KN, M. Hagen
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Origin: Risoe
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Date: August 1998
Description
Input parameters
Parameters in boldface are required; the others are optional.
|
Name |
Unit |
Description |
Default |
|
|
|||
|
nt |
1 |
Number of time bins |
20 |
|
filename |
string |
Name of file in which to store the detector image |
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 |
|
xwidth |
m |
Width of detector. Overrides xmin, xmax |
0 |
|
yheight |
m |
Height of detector. Overrides ymin, ymax |
0 |
|
tmin |
mu-s |
Lower time limit |
0 |
|
tmax |
mu-s |
Upper time limit |
0 |
|
dt |
mu-s |
Length of each time bin |
1.0 |
|
restore_neutron |
1 |
If set, the monitor does not influence the neutron state |
0 |
|
nowritefile |
1 |
If set, monitor will skip writing to disk |
0 |
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Links
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Component source code found in file TOF_monitor.comp.
The time-of-flight monitor
The component TOF_monitor has a rectangular opening in the \((x,y)\) plane, given by the \(x\) and \(y\) parameters, like for Slit. The neutron ray is propagated to the plane of the monitor by the kernel call PROP_Z0. A neutron ray is counted if it passes within the rectangular opening given by the \(x\) and \(y\) limits.
Special about TOF_monitor is that it is sensitive to the arrival time, \(t\), of the neutron ray. Like in a real time-of-flight detector, the time dimension is binned into small time intervals. Hence this monitor maintains a one-dimensional histogram of counts. The \(n_\textrm {chan}\) time intervals begin at \(t_0\) and end at \(t_1\) (alternatively, the interval length is specified by \(\Delta t\)). As usual in time-of-flight analysis, all times are given in units of \(\mu \)s.
The output parameters from TOF_monitor are the three count numbers, \(N, I\), and \(M_2\) for the total counts in the monitor. In addition, a file, filename, is produced with a list of the same three data divided in different TOF bins. This file can be read and plotted by the mcplot tool; see the System Manual.
