%--the poster is one beamer frame, so we have to start with:
\begin{frame}[t]
	%--to seperate the poster in columns we can use the columns environment
	\begin{columns}[t] % the [t] options aligns the columns content at the top
		\begin{column}{\onecolwid}% the right size for a 3-column layout
			%--abstract block--------------------------------------------------------
			\begin{alertblock}{Introduction}
				Charged lepton flavor violation (cLFV) has yet to be observed and is
				known to be sensitive to new physics beyond the Standard Model (SM).
				Various extensions of the SM predicts that cLFV occurs at a detectable
				branching ratio. Therefore, from experimental point of view, it is
				attractive to search for cLFV with more powerful beams and better
				detection technologies.

				Among the cLFV processes, $\mu-e$ conversion, a coherent neutrino-less
				conversion of muon to electron in the presence of a nucleus: \muecaz,
				is our interest. We have proposed a new search for $\mu -e$ conversion
				at J-PARC, the E21 experiment - \textcolor{red}{COMET}(
				\textcolor{red}{COherent Muon to Electron Transition}). The single
				event sensitivity (SES) of COMET will be $2.6\times10^{-17}$, which is
				10,000
				times better than that of the current experimental limit 
				set by SINDRUM II at $7\times10^{-13}$.

			\end{alertblock}

			\begin{alertblock}{Staging approach of the COMET}
				In order to realize the COMET experiment, a two-stage approach has been
				taken. COMET Phase-I aims at an intermediate SES of $3\times10^{-15}$,
				which is an improvement of a factor of 100 compares to SINDRUM II. In
				addition, the COMET Phase-I will make direct measurement of the proton
				beam extinction and other potential background sources for the COMET
				Phase-II experiment, using the actual COMET beam line. 

				\begin{figure}[h!]
					\begin{center}
						\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_phase_1}
					\end{center}
					\caption{Schematic layout of the COMET}
					\label{fig:cometscheme}
				\end{figure}
				The COMET Phase-I funding has been approved. Experimental hall
				construction and beam
				line design are in progress, and expected to finish in 2015. The layout
				of the COMET beam line at Hadron Hall, J-PARC is shown in the Fig.
				\ref{fig:cometbeamline}. For the COMET Phase-I, we will
				construct the first 90 degrees of the muon beam line before extracting
				to the experimental area. Data taking is expected to start around 2016.

				\begin{figure}[h!]
					\begin{center}
						\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_beamline}
					\end{center}
					\caption{COMET beam line at Hadron hall}
					\label{fig:cometbeamline}
				\end{figure}
			\end{alertblock}
		\end{column}
		%===rightcolumn=================================================================
		% here the the middle and right column are put into one big column, this allows
		% to change between 2 and 3 column style
		%\begin{column}{0.60\paperwidth} %thats the big right column
		%\begin{block}{}
		%===two right columns===========================================================
		% we have to give the total width for the column wich is equal to the sum of
		% two colums and the space between them, this is needed to make shure the two
		% cols take all the space of the 'mother' column 
		%\begin{columns}[t,totalwidth=0.60\paperwidth]
		% and then we put in two normal sized columns
		\begin{column}{\twocolwid}
			\begin{figure}[h!]
				\begin{center}
					\includegraphics[width=0.99\twocolwid]{../figs/comet/comet_phase1_layout.png}
				\end{center}
				\caption{Schematic lay out of the COMET Phase I}
				\label{fig:phase1}
			\end{figure}
			\vskip-2ex
			\begin{columns}[t,totalwidth=\twocolwid]
				\begin{column}{\onecolwid}
					\begin{alertblock}{Proton beam}
						COMET Phase-I will use an 8 GeV, 0.4 $\mu$A ($2.5 \times 10^{12}$
						protons/sec), slowly extracted proton
						beam from the J-PARC main ring (MR). One option for the bunch
						structure of the proton beam is shown in Fig \ref{fig:pbeam}.
						\begin{figure}[]
							\includegraphics[width=0.75\onecolwid]{../figs/comet/comet_pbeam_config}
							\caption{COMET proton beam acceleration bunch configuration}
							\label{fig:pbeam}
						\end{figure}
					\end{alertblock}
					\begin{alertblock}{Muon transportation}
						The muon beam line of COMET Phase-I includes the pion capture
						section and the muon transport section up to the end of first
						$90^o$ bend. A high solenoidal field of 5 T is used in the pion
						capture section to capture as many pions as possible. Pions and
						muons - produced when pions decay in flight - goes to
						a matching section, before going to the transport section with
						a 3 T field. A prototype of this system has been built and operated
						successfully at Osaka University.

						Negative muons  are selected by a dipole field, which 
						is created by an additional winding on top of the solenoid
						windings. A collimator is placed in front of the detector section
						to eliminate high momentum muons (and survival pions).
						\begin{figure}[]
							\includegraphics[width=0.75\onecolwid]{../figs/comet/mu_momentum_phase1}
							\caption{Muon momentum before (upper) and after (lower) the collimator}
							\label{fig:mumomentum}
						\end{figure}
					\end{alertblock}
				\end{column}

				\begin{column}{\onecolwid}
					\begin{alertblock}{Detectors for COMET Phase-I}
						There will be two detectors for two goals of COMET Phase-I: physics
						measurements and background measurements. 
						
						Detector for background measurements consists of a solenoid magnet,
						0.8 - 1 T, 5 straw tube tracker layers and a crystal calorimeter.
							This is regarded as a final prototype for Phase-II detector.
						A lot of detector R\&D  activities are ongoing: ECAL
						with GSO/LYSO crystals and APD readout; prototype of straw tube
						tracker; front end electronic board.
						\vskip-2ex
						\begin{figure}[!h]
							\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_p1_det_bg}
						\vskip-2ex
							\caption{Concept of the detector for background measurements}
							\label{fig:phys_det}
						\end{figure}
						There are two options for the detector for $\mu-e$
						conversion search. Baseline detector is a cylindrical drift chamber
						(CDC), shown in the detector section in Fig.
						\ref{fig:phase1}. The CDC would help reducing background rate and
						hit rate. The other option is a transverse tracker, in
						which the detector for background measurements will be reused.

						The CDC is placed inside a magnetic field of 1 - 1.5 T. The
						magnetic field and radial size of the CDC are adjusted to accept
						particles with momentum larger than 70 MeV/c. Segmented triger
						hodoscope is located before the drift chamber, provides timing
						signal and reduces protons hit rate on the chamber. In order to
						reach the goal SES, energy resolution requirement for the CDC is
						1.5 MeV at 105 MeV.
					\end{alertblock}
					\begin{alertblock}{Schedule}
						\begin{figure}[!h]
							\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_phase1_sched}
							%\caption{Technical driven schedule of COMET Phase-I}
							\label{fig:sched}
						\end{figure}
					\end{alertblock}
				\end{column}
			\end{columns}

		%\begin{column}{\onecolwid}
			%\vskip2ex
			%\begin{block}{References}
				%\small{\begin{thebibliography}{99}
						%\bibitem{cdr} The COMET Collaboration, ``Conceptual Design Report for
						%Experimental Search for Lepton Flavor Violating $\mu^--e^-$ 
						%Conversion at
						%Sensitivity of $10^{-16}$ with a Slow-Extracted Bunched Proton Beam
						%(COMET)'', KEK-2009-10 
						%\bibitem{loi} The COMET Collaboration, ``Letter of Intent for Phase-I
							%of the COMET Experiment at J-PARC'', J-PARC-2012-3
					%\end{thebibliography}}
				%\end{block}
			%\end{column}

				\end{column}
				\end{columns}
			\end{frame}
