89 lines
4.4 KiB
TeX
89 lines
4.4 KiB
TeX
\chapter*{Introduction}
|
|
\thispagestyle{empty}
|
|
\addcontentsline{toc}{chapter}{Introduction}
|
|
\label{cha:introduction}
|
|
|
|
%% Restart the numbering to make sure that this is definitely page #1!
|
|
\pagenumbering{arabic}
|
|
|
|
|
|
%\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 sensitivity of $6\times10^{-17}$, 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 in 2016 with
|
|
the goal sensitivity of $3\times 10^{-15}$ after a three-month-running period.
|
|
|
|
A cylindrical drift chamber being developed by the Osaka University group
|
|
will be the 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}.
|
|
|
|
% chapter introduction (end)
|