\section{TOF\_monitor: The time-of-flight monitor}
%\component{TOF\_monitor}{System}{$x_\textrm{min}$, $x_\textrm{max}$, $y_\textrm{min}$, $y_\textrm{max}$, $n_\textrm{chan}$, $t_0$, $t_1$, filename}{$\Delta t$}{}
\index{Monitors!Time-of-flight monitor}
\mcdoccomp{monitors/TOF_monitor.parms}

The component \textbf{TOF\_monitor} has a rectangular opening
in the $(x,y)$ plane, given by the $x$ and $y$ parameters,
like for \textbf{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 \textbf{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 \textbf{TOF\_monitor} are the three count numbers,
$N, I$, and $M_2$ for the total counts in the monitor.
In addition, a file, \verb+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 \textrm{mcplot} tool; see the
System Manual.

