%\section{Chamber technology, layout and construction}
\section{Replacement in the EM forward chambers : (Shikma, Masaya)}
\subsection{introduction}
In view of phase-2 Muon trigger upgrade, it has been studied
to use the MDT drift-time information for the Level-0 muon trigger
to improve the momentum resolution and for getting a shaper
turn-on curve in terms of muon $p_{T}$. The ATLAS muon spectrometer
consists of three stations, inner, middle and outer station, 
in the both barrel and endcap regions. The highest hit occupancy of xxx Hz/cm$^{2}$
at the luminosity of $5\times10^{34}cm^{-2}s^{-1}$ is estimated
in the region of endcap-inner (EI) station, where new chambers, Micro-Megas
and sTGC, will be installed as a part of the ATLAS phase-1 upgrade project.
The characteristic of high-rate tolerance was one of the important point for 
the technology choice, and both technologies satisfies the requirement to work
as precision trackers and trigger chambers.\par
 The second highest occupancy is observed in the endcap-middle (EM) station
especially in the nearest chambers to the beam-line. The hit rate of xxx Hz
at the luminosity of $5\times10^{34}cm^{-2}s^{-1}$ is estimated.
The chamber technologies used in the EM station are MDT for precision tracking
and triplet-TGC for trigger. Both of them still survive under the hit rate of yyy Hz/cm$^2$
and no concerns about aging for the entire life of HL-LHC, a worry was
expressed that the efficiency for finding track-segments in the EM station
of the MDT trigger may be deteriorated due to this higher hit occupancy.
With this background, a possibility to replace EM forward chamber
has been discussed.

\subsection{Expected hit rate}
\begin{itemize}
	\item Require some studies (Ilia? or studies may be available)
\end{itemize}

\subsection{segment finding efficiency as a function of MDT hit occupancy}
\begin{itemize}
	\item to ask inputs from Oliver
\end{itemize}

\subsection{discussion and conclusion}
\begin{itemize}
	\item The current EM1 MDT chambers still work for the MDT trigger.
	\item The current TGC forward chambers survive under the hit occupancy of ... 
\end{itemize}

\newpage

\section{A proposal to replace EIL4 chambers : (Shikma, Masaya)}
In the transition region of the ATLAS muon spectrometer between barrel and endcap,
1.0 < $\eta$ < 1.3, has a complexed structure due to interference
between detectors and the structure of the toroid magnets.
The endcap region is covered by the EIL4 TGC doublets for trigger and
MDT chambers for precision tracking for ~70\% (?) in the azimuthal angle.
The rest will be covered by the BIS-7/8 RPC triplets for trigger and
sMDT chambers and this is a part of the ATLAS phase-1 upgrade project.\\
\par

*** better to have a reference figure to guide***\\

A majority logic of 2 out of 3 coincidence will be applied to the BIS-7/8 RPC
and provided for taking further coincidence between the Big-Wheel TGC,
while 70\% of the transition region is covered by EIL4-TGC and taking
"OR" of two layers. Due to high occupancy in the endcap inner-station
and the poor algorithm due to limited number of layers, the probability
for taking chance coincidence will be increased significantly. ( quantatively ? )\par


\subsection{Expected hit rate}
\begin{itemize}
	\item Require some studies (Ilia? or studies have been available ?)
\end{itemize}

\subsection{Current configuration - low granularity doubles}
Require some studies (Daniel?)\\
\\
The readout electronics of the TGC EIL4 chambers are shared by the
current TGC Small-Wheel chambers. The TGC FI chambers will be
removed when the New Small-Wheel is installed. The legacy
electronics boards stay in the pit as long as the EIL4 TGC
stay in the pit which may cause different type of difficulties
in terms of maintenance.\\

\subsection{High granularity triplets / quadruplets ?}
Require some studies (Daniel?)\\
\\
It might be good to consider EIL4 TGC to the new technology having
at least 3-layers to apply a coincidence logic.

