\section{PSD\_monitor: The PSD monitor}
\index{Monitors!Position sensitive detector (PSD)}
\mcdoccomp{monitors/PSD_monitor.parms}

The component \texttt{PSD\_monitor} resembles other monitors, e.g.
\texttt{Monitor}, and also propagates the photon ray to the detector
surface in the $(x,y)$-plane, where the detector window is set
by the $x$ and $y$ input coordinates.
The PSD monitor is sensitive to the arrival position of the of the photon ray.
The rectangular monitor window, given by the $x$ and $y$
limits is divided into $n_x \times n_y$ pixels.

The output from \texttt{PSD\_monitor} is the integrated counts, $n, I, M_2$,
as well as
three two-dimensional arrays of counts: $n(x,y), I(x,y), M_2(x,y)$.
The arrays are written to a file, \verb+filename+, and can be read e.g. by the tool
\textbf{mxplot}, see the system manual.
