206 lines
9.0 KiB
TeX
206 lines
9.0 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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\textcolor{red}{Charged lepton flavor violation (cLFV)} has yet to be
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observed and is known to be sensitive to new physics beyond the
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Standard Model (SM).
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Various extensions of the SM predicts that cLFV occurs at some detectable
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branching ratio. Therefore, from experimental point of view, it is
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very attractive to search for cLFV with more powerful beams and better
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detection techniques.
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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 the COMET will be
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\textcolor{red}{$2.6\times10^{-17}$}, 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 \textcolor{red}{$7\times10^{-13}$}.
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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. The first stage, \textcolor{red}{COMET Phase-I} has two major
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goals:
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\begin{enumerate}
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\item \textcolor{red}{Search for $\mu-e$ conversion}: we aim at an
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intermediate SES of \textcolor{red}{$3\times10^{-15}$}, which is an
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improvement of a factor of 100 compares to SINDRUM II.
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\item \textcolor{red}{Background measurements} for full COMET: make
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direct measurement of the proton beam extinction and other
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potential background sources, using the actual COMET beam line.
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\end{enumerate}
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\begin{figure}[h!]
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\begin{center}
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\includegraphics[width=0.96\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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Layout of the COMET experiment at Hadron Hall, J-PARC is shown in the
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Fig~\ref{fig:cometbeamline}. For the COMET Phase-I, we will construct
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the first \textcolor{red}{90 degrees} of the muon beam line before
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extracting to the experimental area.
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The COMET Phase-I \textcolor{red}{funding has been approved} by KEK.
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This will cover
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experimental hall and beam line construction. The construction is
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expected to finish in 2015, then data taking would start around
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2016.
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\begin{figure}[h!]
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\begin{center}
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\includegraphics[width=0.940\onecolwid]{../figs/comet/comet_in_hadron_hall}
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\end{center}
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\vskip1.6ex
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\caption{COMET beam line in the Hadron Hall extension plan}
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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=0.99\twocolwid]{../figs/comet/comet_phase1_layout.png}
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\end{center}
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\caption{Concept of the COMET Phase-I}
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\label{fig:phase1}
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\end{figure}
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\vskip-2ex
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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 \textcolor{red}{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 proposed configuration for
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the bunch structure of the proton beam is shown in
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Fig~\ref{fig:pbeam}.
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\begin{figure}[]
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\includegraphics[width=0.65\onecolwid]{../figs/comet/comet_pbeam_config}
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\vskip-1.5ex
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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. The field in the superconducting pion capture solenoid
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is 5 T. 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 solenoid with
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a 3 T field. \textcolor{red}{A prototype of this system has been
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built and operated 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=0.70\onecolwid]{../figs/comet/mu_stop_phase1}
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\vskip-1.5ex
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\caption{Momentum distribution of muons approaching the target
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(open histogram) and those stopped by it (red)}
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\label{fig:mustop}
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\end{figure}
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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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\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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\begin{enumerate}
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\item \textcolor{red}{$\mu-e$ conversion search:}
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There are two candidates for the detector for the
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search. \textcolor{red}{Baseline detector is a cylindrical
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drift chamber (CDC)}, shown in the detector section in
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Fig~\ref{fig:phase1}.
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The CDC is chosen because it would help reducing background rate
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and hit rate. The alternative option is using the same detector
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for background measurements: a tranverse tracker, which is
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decribed below.
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The CDC is placed inside a magnetic field of 1 - 1.5 T. It is
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tuned to accept particles with momentum larger than 70 MeV/c.
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Segmented triger hodoscope is located before the drift chamber,
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provides timing signal and reduces protons hit rate on the
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chamber. In order to reach the goal SES, energy resolution
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requirement for the CDC is \textcolor{red}{1.5 MeV at 105 MeV}.
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%\vskip-1ex
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\begin{figure}[!h]
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\includegraphics[width=0.90\onecolwid]{../figs/comet/comet_signal}
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\vskip-1ex
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\caption{Signal of $\mu-e$ conversion, electron with
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momentum of about 105 MeV/c (red); and background from electron
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from muon decay in orbit (blue).}
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\label{fig:signal}
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\end{figure}
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\item \textcolor{red}{Background measurements:}
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A \textcolor{red}{tranverse tracker} will be used. It consists
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of a solenoid magnet, 0.8
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- 1 T, 5 straw tube tracker layers and a crystal calorimeter.
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This is regarded as a final \textcolor{red}{prototype for
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Phase-II detector}.
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\begin{figure}[!h]
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\includegraphics[width=0.90\onecolwid]{../figs/comet/comet_p1_det_bg}
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\vskip-1ex
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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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\end{enumerate}
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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; calculation and wire
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chamber test for CDC; \ldots
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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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