\chapter*{Introduction}
\thispagestyle{empty}
\addcontentsline{toc}{chapter}{Introduction}
\label{cha:introduction}

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%\begin{itemize}
  %\item CLFV in 3 lines
  %\item COMET in 3 lines
  %\item structure of the thesis:
    %\begin{itemize}
      %\item physics motivation of CLFV, COMET (chap 1)
      %\item overview of COMET, Phase-I, requirements for detectors (chap 2)
      %\item details of the proton measurements:
        %\begin{itemize}
          %\item physics (chap 3)
          %\item method (chap 4)
          %\item experimental set up, calibration (chap 4? or 5 )
          %\item data analysis (chap 5)
          %\item results, impact (chap 6)
        %\end{itemize}
    %\end{itemize}
%\end{itemize}
%\begin{comment}
%The Standard Model (SM) is the most successful theory of particle physics 
%as it could account for almost all experimental data from high energy
%experiments. The discovery of a Higgs-like boson at the LHC in 2012 is another
%triumph of the theory. However, it is known that the SM has its limitations,
%one example is there is no explanation for the existence of lepton
%flavours and flavour conservation.
%theory. For example, it does not explain the origin of mass, the nature of dark
%matter, or neutrino oscillations.

%The lepton flavour conservation in the SM is assured by assuming neutrinos are
%massless. But, extensive experiments with atmospheric, solar, accelerator,
%reactor neutrinos have shown that neutrinos have non-zero masses, and they do
%mix between flavours~\cite{BeringerArguin.etal.2012}. In other words, lepton
%flavour violation (LFV) does occur in neutrino oscillations.

%While lepton flavour is totally violated in the neutrino sector, no charged
%lepton flavour violation (CLFV) has ever been observed. Therefore, any
%experimental evidence of lepton flavour violation with charged lepton would be
%a breakthrough that leads to new physics beyond the SM.
%\end{comment}
%The Standard Model (SM) is the most successful theory of particle physics 
%as it could account for almost all experimental data from high energy
%experiments. However, it is also known that the SM has its 
%TODO: wording /duplicaitons
The COMET experiment~\cite{COMET.2007}, proposed at the Japan Proton
Accelerator Research Complex (J-PARC), is a next-generation-experiment that
searches for evidence of charged lepton flavour violation (CLFV) with muons.
The branching ratio of CLFV in the Standard Model, even with massive neutrinos,
is prohibitively small, at the order of $10^{-54}$. Therefore, any experimental
observation of CLFV would be a clear signal of new physics beyond the SM.

The COMET (\textbf{CO}herent \textbf{M}uon to \textbf{E}lectron
\textbf{T}ransition) Collaboration aims to probe the conversion of a muon to
an electron in a nucleus field at a single event sensitivity of \num{6E-17},
pushing for a four orders of magnitude improvement from the current limit set
by the
SINDRUM-II~\cite{Bertl.etal.2006}. A staging approach is adopted at the COMET
to achieve an intermediate physics result, as well as to gain operational
experience. The first stage, COMET Phase I, is scheduled to start data taking
in 2016 with the goal single event sensitivity of $3.1\times 10^{-15}$ after
a three-month running period. 

A cylindrical drift chamber being developed by the Osaka University group
together with the Kyushu University group and the Chinese groups
will be a main tracking detector in the COMET Phase I. It is anticipated that 
the chamber will be heavily occupied by protons emitted after nuclear muon
capture in the stopping target, and thus an absorber will be installed to
reduce the proton hit rate to a tolerable level. A study of proton emission
following nuclear muon capture for optimisation of the proton absorber is
presented in this thesis.

The thesis is structured as follows: 
firstly,
the physics motivation of the COMET experiment, with muon's normal decays and
CLFV decays, is described in Chapter~\ref{cha:clfv}.
Chapter~\ref{cha:comet_overview} gives an overview of the
COMET experiment: beam lines, detectors and their requirements, and expected
sensitivities. Details of the study on proton emission are described in
Chapters~\ref{cha:alcap_phys},~\ref{cha:the_alcap_run_2013},~\ref{cha:data_analysis}:
physics, method, experimental set up, data analysis. The results and impacts of
the study on COMET Phase-I design is discussed in
Chapter~\ref{cha:discussions_on_the_impact_to_the_comet_phase_i}.

% chapter introduction (end)
