173 lines
7.9 KiB
TeX
173 lines
7.9 KiB
TeX
%--the poster is one beamer frame, so we have to start with:
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\begin{frame}[t]
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%--to seperate the poster in columns we can use the columns environment
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\begin{columns}[t] % the [t] options aligns the columns content at the top
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\begin{column}{\onecolwid}% the right size for a 3-column layout
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%--abstract block--------------------------------------------------------
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\begin{alertblock}{Introduction}
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Charged lepton flavor violation (cLFV) has yet to be observed and is
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known to be sensitive to new physics beyond the Standard Model (SM).
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Various extensions of the SM predicts that cLFV occurs at a detectable
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branching ratio. Therefore, from experimental point of view, it is
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attractive to search for cLFV with more powerful beams and better
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detection technologies.
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Among the cLFV processes, $\mu-e$ conversion, a coherent neutrino-less
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conversion of muon to electron in the presence of a nucleus: \muecaz,
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is our interest. We have proposed a new search for $\mu -e$ conversion
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at J-PARC, the E21 experiment - \textcolor{red}{COMET}(
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\textcolor{red}{COherent Muon to Electron Transition}). The single
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event sensitivity (SES) of COMET will be $2.6\times10^{-17}$, which is
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10,000
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times better than that of the current experimental limit
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set by SINDRUM II at $7\times10^{-13}$.
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\end{alertblock}
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\begin{alertblock}{Staging approach of the COMET}
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In order to realize the COMET experiment, a two-stage approach has been
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taken. COMET Phase-I aims at an intermediate SES of $3\times10^{-15}$,
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which is an improvement of a factor of 100 compares to SINDRUM II. In
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addition, the COMET Phase-I will make direct measurement of the proton
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beam extinction and other potential background sources for the COMET
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Phase-II experiment, using the actual COMET beam line.
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\begin{figure}[h!]
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\begin{center}
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\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_phase_1}
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\end{center}
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\caption{Schematic layout of the COMET}
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\label{fig:cometscheme}
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\end{figure}
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The COMET Phase-I funding has been approved. Experimental hall
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construction and beam
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line design are in progress, and expected to finish in 2015. The layout
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of the COMET beam line at Hadron Hall, J-PARC is shown in the Fig.
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\ref{fig:cometbeamline}. For the COMET Phase-I, we will
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construct the first 90 degrees of the muon beam line before extracting
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to the experimental area. Data taking is expected to start around 2016.
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\begin{figure}[h!]
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\begin{center}
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\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_beamline}
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\end{center}
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\caption{COMET beam line at Hadron hall}
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\label{fig:cometbeamline}
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\end{figure}
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\end{alertblock}
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\end{column}
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%===rightcolumn=================================================================
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% here the the middle and right column are put into one big column, this allows
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% to change between 2 and 3 column style
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%\begin{column}{0.60\paperwidth} %thats the big right column
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%\begin{block}{}
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%===two right columns===========================================================
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% we have to give the total width for the column wich is equal to the sum of
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% two colums and the space between them, this is needed to make shure the two
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% cols take all the space of the 'mother' column
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%\begin{columns}[t,totalwidth=0.60\paperwidth]
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% and then we put in two normal sized columns
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\begin{column}{\twocolwid}
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\begin{figure}[h!]
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\begin{center}
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\includegraphics[width=0.90\twocolwid]{../figs/comet/comet_phase1_tracker.pdf}
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\end{center}
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\caption{Schematic lay out of the COMET Phase I}
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\label{fig:phase1}
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\end{figure}
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\begin{columns}[t,totalwidth=\twocolwid]
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\begin{column}{\onecolwid}
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\begin{alertblock}{Proton beam}
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COMET Phase-I will use an 8 GeV, 0.4 $\mu$A ($2.5 \times 10^{12}$
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protons/sec), slowly extracted proton
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beam from the J-PARC main ring (MR). One option for the bunch
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structure of the proton beam is shown in Fig \ref{fig:pbeam}.
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\begin{figure}[]
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\includegraphics[width=0.75\onecolwid]{../figs/comet/comet_pbeam_config}
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\caption{COMET proton beam acceleration bunch configuration}
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\label{fig:pbeam}
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\end{figure}
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\end{alertblock}
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\begin{alertblock}{Muon transportation}
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The muon beam line of COMET Phase-I includes the pion capture
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section and the muon transport section up to the end of first
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$90^o$ bend. A high solenoidal field of 5 T is used in the pion
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capture section to capture as many pions as possible. Pions and
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muons - produced when pions decay in flight - goes to
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a matching section, before going to the transport section with
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a 3 T field. A prototype of this system has been built and operated
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successfully at Osaka University.
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Negative muons are selected by a dipole field, which
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is created by an additional winding on top of the solenoid
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windings. A collimator is placed in front of the detector section
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to eliminate high momentum muons (and survival pions).
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\begin{figure}[]
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\includegraphics[width=0.75\onecolwid]{../figs/comet/mu_momentum_phase1}
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\caption{Muon momentum before (upper) and after (lower) the collimator}
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\label{fig:mumomentum}
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\end{figure}
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\end{alertblock}
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\end{column}
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\begin{column}{\onecolwid}
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\begin{alertblock}{Detectors for COMET Phase-I}
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There will be two detectors for two goals of COMET Phase-I: physics
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measurements and background measurements.
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Detector for background measurements consists of a solenoid magnet,
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0.8 - 1 T, 5 straw tube tracker layers and a crystal calorimeter.
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This is regarded as a final prototype for Phase-II detector.
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A lot of detector R\&D activities are ongoing: ECAL
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with GSO/LYSO crystals and APD readout; prototype of straw tube
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tracker; front end electronic board.
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\vskip-2ex
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\begin{figure}[!h]
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\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_p1_det_bg}
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\caption{Concept of the detector for background measurements}
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\label{fig:phys_det}
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\end{figure}
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There are two options for the detector for $\mu-e$
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conversion search. Baseline detector is a cylindrical drift chamber
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(CDC), shown in the detector section in Fig.
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\ref{fig:phase1}. The CDC would help reducing background rate and
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hit rate. The other option is a transverse tracker, in
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which the detector for background measurements will be reused.
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The CDC is placed inside a magnetic field of 1 - 1.5 T. The
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magnetic field and radial size of the CDC are adjusted to accept
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particles with momentum larger than 70 MeV/c. Segmented triger
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hodoscope is located before the drift chamber, provides timing
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signal and reduces protons hit rate on the chamber. In order to
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reach the goal SES, energy resolution requirement for the CDC is
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1.5 MeV at 105 MeV.
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\end{alertblock}
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\begin{alertblock}{Schedule}
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\begin{figure}[!h]
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\includegraphics[width=0.95\onecolwid]{../figs/comet/comet_phase1_sched}
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%\caption{Technical driven schedule of COMET Phase-I}
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\label{fig:sched}
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\end{figure}
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\end{alertblock}
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\end{column}
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\end{columns}
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%\begin{column}{\onecolwid}
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%\vskip2ex
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%\begin{block}{References}
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%\small{\begin{thebibliography}{99}
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%\bibitem{cdr} The COMET Collaboration, ``Conceptual Design Report for
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%Experimental Search for Lepton Flavor Violating $\mu^--e^-$
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%Conversion at
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%Sensitivity of $10^{-16}$ with a Slow-Extracted Bunched Proton Beam
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%(COMET)'', KEK-2009-10
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%\bibitem{loi} The COMET Collaboration, ``Letter of Intent for Phase-I
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%of the COMET Experiment at J-PARC'', J-PARC-2012-3
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%\end{thebibliography}}
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%\end{block}
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%\end{column}
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\end{column}
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\end{columns}
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\end{frame}
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