During R2013, there were data collected for both silicon and aluminium
targets with the aluminium data being most useful for COMET and Mu2e
and the silicon data being collected so that a cross check with the
existing silicon data~\cite{sobo68} could be performed.

For both materials, two different target thicknesses were used.
For silicon, a thick, active target of 1500 \textmu m thickness was used with
three different beam momenta to investigate muons stopping on the surface of
the target and muons stopping closer to the centre. In addition, a thin,
passive silicon target of 62 \textmu m was used.

For aluminium, there were two different target thicknesses:
100 \textmu m and 50 \textmu m with the muon beam momentum tuned so that the
muon beam stopped towards the centre of the target.

Table~\ref{tab:alcap:datasets} summarises the datasets and gives the
muon beam momentum as a scale factor and the total number of muons
as entering the experiment as counted by the $\mu$Sc beam scintillator counter.

\begin{table}
  \centering
  \caption{Summary of the data that was collected during Run2013.}
    \begin{tabular}{cccl}
      \addlinespace
      \toprule
      \bf Target & \bf Beam Momentum & \bf Number of Muons & \bf Comments \\
             & [$\times$\SI{28}{MeV\per \cc}] & & \\
      \midrule
      %\hline
      Si (1500 \textmu m) & 1.32 & $2.78\times10^{7}$ & Active Target\\
                              & 1.30 & $2.89\times10^{8}$ & Cross check with \\
                              & 1.10 & $1.37\times10^{8}$ & existing Si data\\
      \addlinespace
      Si (62 \textmu m) & 1.06 & $1.72\times10^{7}$ & Passive Target\\
      \addlinespace
      Al (100 \textmu m) & 1.09 & $2.94\times10^{8}$ & \\
                             & 1.07 & $4.99\times10^{7}$ & \\
      \addlinespace
      Al (50 \textmu m) & 1.07 & $8.81\times10^{8}$ & \\
      \bottomrule
    \end{tabular}
  \label{tab:alcap:datasets}
\end{table}

For all datasets, the aim was to measure the proton emission spectrum and normalise to the number of stopped muons by analysing the X-ray spectrum. In addition, preliminary investigations were made into the gamma ray and neutron emission spectra in preparation for a future run.