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thesis/chapters/chap6_analysis.tex

@@ -1,116 +1,14 @@
 \chapter{Data analysis}
 \label{cha:data_analysis}
-
-\section{Analysis modules}
-\label{sec:analysis_modules}
-A full analysis has not been completed yet, but initial analysis
-based on the existing modules (\cref{tab:offline_modules}) is possible
-thanks to the modularity of the analysis framework. 
-
-\begin{table}[htb]
-  \begin{center}
-    \begin{tabular}{l p{8cm}}
-      \toprule
-      \textbf{Module name} & \textbf{Functions}\\
-      \midrule
-      MakeAnalysedPulses  & make a pulse with parameters extracted from
-      a waveform\\
-      MaxBinAPGenerator   & simplest algorithm to get pulse information\\
-      TSimpleMuonEvent    & sort pulses occur in a fixed time window around the
-      muon hits\\
-      ExportPulse \& PulseViewer & plot waveforms for diagnostics\\
-      PlotAmplitude       & plot pulse height spectra\\
-      PlotAmpVsTdiff      & plot pulse correlations in timing and amplitude\\
-      EvdE                & identify charged particles using dE/dx\\
-      \bottomrule
-    \end{tabular}
-  \end{center}
-  \caption{Available offline analysis modules.}
-  \label{tab:offline_modules}
-\end{table}
-
-The MakeAnalysedPulses module takes a raw waveform, calculates the pedestal
-from a predefined number of first samples, subtracts this pedestal taking
-pulse polarity into account, then calls another module to extract pulse
-parameters. At the moment, the simplest module, so-called MaxBinAPGenerator,
-for pulse information calculation is in use. The module looks for the
-sample that
-has the maximal deviation from the baseline, takes the deviation as pulse
-amplitude and the time stamp of the sample as pulse time. The procedure is
-illustrated on \cref{fig:tap_maxbin_algo}. This module could not account for
-pile-up or double pulses in one \tpulseisland{} in \cref{fig:tap_maxbin_bad}.
-\begin{figure}[htb]
-  \centering
-    \includegraphics[width=0.85\textwidth]{figs/tap_maxbin_algo}
-  \caption{Pulse parameters extraction with MaxBinAPGenerator.}
-  \label{fig:tap_maxbin_algo}
-\end{figure}
-\begin{figure}[htb]
-  \centering
-    \includegraphics[width=0.47\textwidth]{figs/tap_maxbin_bad}
-    \includegraphics[width=0.47\textwidth]{figs/tap_maxbin_bad2}
-  \caption{Double pulse and pile up are taken as one single pulse by the
-    MaxBinAPGenerator}
-  \label{fig:tap_maxbin_bad}
-\end{figure}
-
-The TSimpleMuonEvent first picks a muon candidate, then loops through all
-pulses on all detector channels, and picks all pulses occur in
-a time window of \SI{\pm 10}{\si{\us}} around each candidate to build
-a muon event. A muon candidates is a hit on the upstream plastic scintillator
-with an amplitude higher than a threshold which was chosen to reject MIPs. The
-period of \SI{10}{\si{\us}} is long enough compared to the mean life time of
-muons in the target materials
-(\SI{0.758}{\si{\us}} for silicon, and \SI{0.864}{\si{\us}}
-for aluminium~\cite{SuzukiMeasday.etal.1987}) so practically all of emitted
-charged particles would be recorded in this time window.
-%\begin{figure}[htb]
-  %\centering
-    %\includegraphics[width=0.85\textwidth]{figs/tme_musc_threshold}
-  %\caption{Pulse height spectrum of the $\mu$Sc scintillator}
-  %\label{fig:tme_musc_threshold}
-%\end{figure}
-
-A pile-up protection mechanism is employed to reject multiple muons events: if
-there exists another muon hit in less than \SI{15}{\si{\us}} from the
-candidate then both the candidate and the other muon are discarded. This
-pile-up protection would cut out less than 11\% total number of events because
-the beam rate was generally less than \SI{8}{\kilo\hertz}.
-
-%In runs with active silicon targets, another requirement is applied for the
-%candidate: a prompt hit on the target in $\pm 200$ \si{\ns}\ around the
-%time of the $\mu$Sc pulse. The number comes from the observation of the
-%time correlation between hits on the target and the $\mu$Sc
-%(\cref{fig:tme_sir_prompt_rational}).
-%\begin{figure}[htb]
-  %\centering
-    %\includegraphics[width=0.85\textwidth]{figs/tme_sir_prompt_rational}
-  %\caption{Correlation in time between SiR2 hit and muon hit}
-  %\label{fig:tme_sir_prompt_rational}
-%\end{figure}
-
-To make sure that we will analyse good data, a low level data quality checking
-was done on the whole data sets. The idea is plotting the variations of basic
-parameters, such as noise level, length of raw waveforms, pulse rate, time
-correlation to hits on the muon counter on each channel during the data
-collecting period. Runs with significant difference from the averaging 
-values were further checked for possible causes, and would be discarded if such
-discrepancy was too large or unaccounted for. Examples of such trend plots are
-shown in \cref{fig:lldq}.
-\begin{figure}[htb]
-  \centering
-    \includegraphics[width=0.47\textwidth]{figs/lldq_noise}
-    \includegraphics[width=0.47\textwidth]{figs/lldq_tdiff}
-  \caption{Example trend plots used in the low level data quality checking:
-    noise level in FWHM (left) and time correlation with muon hits (right). The
-    noise level was basically stable in in this data set, except for one
-    channel. On the right hand side, this sanity check helped find out the
-    sampling frequency was wrongly applied in the first tranche of the data
-    set.}
-  \label{fig:lldq}
-\end{figure}
-% section analysis_modules (end)
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+This chapter presents initial analysis on subsets of the collected data.
+Purposes of the analysis include:
+\begin{itemize}
+  \item testing the analysis chain;
+  \item verification of the experimental method, specifically the
+    normalisation of number of stopped muons, and particle identification
+    using specific energy loss;
+  \item extracting a preliminary rate of proton emission from aluminium.
+\end{itemize}
 \section{Charged particles following muon capture on a thick silicon target}
 \label{sec:charged_particles_from_muon_capture_on_silicon_thick_silicon}
 This analysis was done on a subset of the active target runs