In addition to what achieved with the RICH detector, further muon suppression is needed up to a level of $10^{-5}$. A calorimetric \textbf{muon veto} system will fulfill this requirement in two steps \cite{na62-tdr}:
\begin{enumerate}
\item A fast muon veto detector (\textbf{MUV3}), with time resolution $\sigma_t \leq 1$ \si{\nano\second}, will reject events featuring coincident signals in the GTK and CEDAR detectors. This will lead to a pions to muons ratio of about 20 already at the first trigger level.
%factor of about 20 of muon suppression with respect to pions already at the first trigger level.
\item Two segmented calorimeters (\textbf{MUV1} and \textbf{MUV2}) will require crossing particles to deposit a significant amount of energy.
%, being able to traverse a sufficiently thick layer of iron. 
In addition, measurements of the shower shape will allow to distinguish those muons undergoing catastrophic Bremsstrahlung or direct pair production from hadrons.\\
\end{enumerate}

The first two modules, placed around the beam line next to the LKr calorimeter, are composed of alternate layers of scintillator (10 \si{\milli\meter} thick) and iron (25 \si{\milli\meter} thick). The total thickness of each module is 62.5 \si{\centi\meter}. The scintillator bars, 130 \si{\centi\meter} long and 4 to 6 \si{\centi\meter} wide, are alternatively oriented along the vertical and horizontal directions.\\

The third module is placed downstream of an 80 \si{\centi\meter} thick iron wall, and serves as fast level 0 trigger. It consists of a matrix of 20$\times$20$\times$5 \si{\centi\meter^3} scintillator blocks read out by photomultipliers.\\

\figurename~\ref{img:det:muv} sketches the layout of the three muon veto stations.\\

\begin{figure}
\centering
\def\svgwidth{0.7\textwidth}
\input{Images/pdf/na62/detector/muv-tex.pdf_tex}
\caption{Layout of the three MUV detectors.}\label{img:det:muv}
\end{figure}