%% \setcounter{figure}{0}

\newpage

\section{Small-Diameter Muon Drift Tube Detectors}

\if{0}
{\it Detail of detector technologies proposed for use in the small wheel 
detector, including the status of developments. Include a description
on the status and size of available prototype chambers.\\

This section should describe the technology up to the level of a
single chamber.
}
\fi

%%% ==== B1 ============================================================
%%%
\subsection{Tracking in a high--back\-ground environment}
\label{Tracking}
%%%
%%% ====================================================================

In order to study the performance of the MDT chambers at high background rates, a full-scale ATLAS
BOS chamber has been extensively tested in the CERN Gamma Irradiation Facility
(GIF)~\cite{ref_deile,ref_horvat}. The results showed that the drift-tube chambers provide
efficient and high-resolution tracking  in combination with fast trigger and second-coordinate
chambers up to very high occupancies above 20~\%~\cite{ref_MDTtracking}, which are expected to be
reached in the ATLAS endcap muon spectrometer already at twice the LHC design luminosity. 

%
% --- Fig.  1 ----------------------------------------------------------------
%
\begin{figure}[!htb]
\centering
\includegraphics[width=0.5\textwidth]{Figures/dtspectrum}
\includegraphics[width=0.45\textwidth]{Figures/rtrelation}
%\vspace{-1cm}

\caption{Drift time spectrum (left) and space-to-drifttime (r-t) relationship (right) of circular drift tubes 
of 30~mm and 15~mm diameter operated with Ar:CO$_2$
(93:7) gas mixture at 3 bar and gas gain of 20000. The Garfield simulation~\cite{ref_garfield} of the drift time spectrum of 15~mm tubes
is overlaid.} 

\label{fig_dtspectrum}
\end{figure}

Reduction of the outer drift-tube diameter from 30~mm in the present ATLAS Monitored Drift Tube
(MDT) chambers to 15~mm while keeping the other parameters, including the gas gain of $2\cdot
10^4$, the sense wire diameter of $50~\mu$m and  the tube wall thickness of 0.4~mm unchanged leads
to a significant improvement of the rate capability  of the drift-tube chambers which is more than
sufficient for their operation in the new Small Wheels at the highest background rates
expected for LHC luminosity upgrades in the forward regions of the ATLAS muon spectrometer.  

%
% --- Table  2 -------------------------------------------------------------------

\begin{table}[!htb]

  \begin{center}
%   
    \begin{tabular}{|l|c|} \hline

     \textbf{Parameter}        &      \textbf{Design value}   \\  \hline

    Tube material              &      Aluminum                \\ 
    Outer tube diameter        &      15.000\,mm              \\
    Tube wall thickness        &      0.4\,mm                 \\ 
    Glue gap between tubes     &      0.1\,mm                 \\
    Wire material              &      Gold-plated W/Re (97/3) \\
    Wire diameter              &      50~$\mu$m               \\
    Wire tension               &      $300\pm 15$~g           \\
    Gas mixture                &      Ar/CO$_2$/H$_2$O (93/7/$\leq 1000$~ppm) \\
    Gas pressure               &      3 bar (absolute)        \\
    Gas gain                   &      2 x $10^4$              \\
    Wire potential~~~~~~~~~~~~~&      2730 V                  \\
    Maximum drift time         &      $\sim$ 185 ns           \\
    \hline

    \end{tabular}
   \caption{The operating parameters of small-diameter MDT chambers.\label{Sml_MDT_parameters}}
  \end{center}
%
\end{table}


The standard MDT operating parameters are kept for the small-diameter drift tubes (see
Table.~\ref{Sml_MDT_parameters}). With the MDT gas mixture of Ar:CO$_2$ (93:7) at 3 bar absolute
pressure, the gas gain of $2\cdot 10^4$ is achieved at an operating voltage of 2730~V for 15~mm
diameter drift tubes.  Under these conditions, the maximum drift time is reduced by a factor of 3.8
from about 700~ns to 185~ns by shrinking the tube diameter by a factor of two (see
Fig.~\ref{fig_dtspectrum}, left)~\cite{ref_bittner1}.
In addition, the background flux hitting a tube is reduced by a factor of two. 
Altogether, the drift-tube occupancy is reduced by a factor of 7.5.  
2 x 6 drift-tube layers at radii $R<2$~m in the Small Wheels and 2 x 4 layers at larger radii are sufficient 
to provide very robust tracking with track segment reconstruction efficiencies of at least 99~\% up to
background rates well above the expected maximum values (see details of the chamber performance below).

% --- Fig. 21 ----------------------------------------------------------------
%
\begin{figure}[!htb]
\centering
\includegraphics[width=0.45\textwidth]{Figures/dtresol30mm}
\includegraphics[width=0.45\textwidth]{Figures/dtresolrate}
%\vspace{-1cm}

\caption{Left: Spatial resolution of 30~mm diameter drift tubes as a function of drift radius for different
background hit rates as measured at the GIF~\cite{ref_deile,ref_horvat}. 
Right: Dependence of the average drift tube resolution on the background hit rate. From the measurements for 
30~mm diameter tubes the expectation for 15~mm diameter tubes is derived (see text).} 

\label{fig_dtresolrate}
\end{figure}


The space-charge distribution caused by the ion clouds drifting towards the tube wall during a
particle crossing modifies the local electric field, influencing both the drift velocity and the
gas gain. By lowering the effective potential experienced  by the electrons drifting towards the
wire, high background flux leads to decreasing gas gain. The resulting signal loss grows with the
inner tube radius $r_2$ proportional to $r_2^3\cdot \ln (r_2/r_1)$ ~\cite{ref_riegler}, 
where $r_1=25~\mu$m is the wire radius, and therefore is about 8 times smaller in 15 mm compared to 30 mm
diameter drift tubes. Fluctuations of space charge and electric field lead to variations
of the drift velocity causing a deterioration of the spatial resolution in non-linear drift gases
like Ar:CO$_2$ where the drift velocity depends on the electric field. The latter effect
increases strongly with the drift distance above a value of about 7.5~mm while the gain drop effect on
the spatial resolution dominates for distances close to the sense wire  (see Fig.~\ref{fig_dtresolrate}, left)
~\cite{ref_aleksa,ref_deile,ref_horvat}).  
For drift radii below 7.5~mm,
i.e. for the 15~mm diameter tubes, the space-to-drift time relationship is more linear leading to
a reduced sensitivity to environmental parameters such as gas composition and density, magnetic
field and irradiation rate (Fig.~\ref{fig_dtspectrum}, right).

Since the spatial resolution of the drift tubes improves with increasing drift radius, the average
single-tube resolution at low background rates and after applying time slewing corrections is degraded 
from $80~\mu$m for 30~mm diameter tubes to about $110~\mu$m for 15~mm diameter tubes. The
average 30~mm diameter tube resolution deteriorates linearly with the background rate to about
$115~\mu$m at 0.5~kHz/cm$^2$ (see Fig.~\ref{fig_dtresolrate}, right)~\cite{ref_horvat}. 
Fig.~\ref{fig_dtresolrate} (right) also shows the linear dependence of the average 15~mm diameter
tube resolution on the background rate derived by averaging the measured 30~mm diameter tube resolutions
in Fig.~\ref{fig_dtresol30mm} over the radial range $r<7.5$~mm and multiplying the corresponding 
background rates by 8 to account for the suppressed gain loss.   
Altogether, the spatial drift tube resolution degrades 10 times slower with the background rate  
for 15~mm compared to 30~mm tube diameter.

The track point resolution of the drift tube chambers in the new Small Wheels with 2 x 4 and 
2 x 6 tube layers, depending on the radial position, will be uniformly $50~\mu$m at the highest
background rates compared to $40~\mu$m without background irradiation.     

%%% ==== B2 ============================================================
%%%
\subsection{Chamber Design}
\label{Technical_Implementation}
%%%
%%% ====================================================================

The design of the muon drift-tube chambers with 15~mm diameter tubes for the new Small Wheels
follows as closely as possible  the current ATLAS MDT chamber design in the endcap region of the muon
spectrometer (Fig.~\ref{fig_smdt_chamber_design}).  The chambers consist of two multilayers of
four or six layers of drift tubes each in densest package. The aluminum tubes of 15~mm outer
diameter and 0.4~mm wall thickness are produced according to industry standard and are chromatized
for cleaning and reliable electric contact. The tubes are separated by 0.1 mm wide glue gaps during
chamber assembly. The two multilayers are separated by a spacer frame carrying the supports of the
integrated drift-tube and trigger chambers on the Small Wheel structure and the in-plane optical
alignment system monitoring the planarity of the chambers. The aluminum spacer frame is of 
similar design as for the present Small Wheel MDT chambers. Modification in the chamber
design are mainly due to the four times denser packaging of the drift tubes and their gas and electrical 
connections.

Central to the chamber design is the design of the drift tubes and of their endplugs (see
Fig.~\ref{fig_smdt_tube_design}).  The aluminum tubes of 15~mm outer diameter and 0.4~mm wall
thickness are produced according to industry standards (DIN) with tolerances of $\pm 0.1$~mm on
diameter, roundness and concentricity of inner and outer circumference and of $\pm 0.5$~mm on
straightness and chromatized for cleaning and reliable electric contact. The endplugs insulate the
sense wire from the tube wall, center the wire in the tubes, position it with respect to the 
external reference surface on the endplug  with an accuracy of better than $10~\mu$m and provide
high-voltage-safe connections to the gas distribution manifold  (see
Fig.~\ref{fig_gasmanifold_design}) and to the  24-channel readout and high-voltage interface boards 
(''hedgehog cards'', Figs.~\ref{fig_hedgehogs}). 

% --- Fig.  4 ----------------------------------------------------------------
%
\begin{figure}[!p] 
\begin{center}
\includegraphics[width=0.6\linewidth,clip]{Figures/smdt_chamber_design3D} 
\includegraphics[width=0.9\linewidth,clip]{Figures/smdt_chamber_design1D} 
%
\caption{Small drift-tube chamber design for the new Small Wheels (EIL1 chamber). 
The integration with the trigger chambers is also shown.
The mounting of the alignment sensors is indicated.}
\label{fig_smdt_chamber_design}
% 
\end{center}
\end{figure}

The wire is fixed at both tube ends in copper crimping tubes inserted into the central brass
inserts of the endplugs and connected to the signal and high-voltage hedgehog cards via brass signal
caps which are screwed onto the brass inserts, sealing the tubes with respect to the gas manifold
with O-rings. The brass insert of the endplug holds the spiral-shaped wire locator (''twister'') in
a central bore on the inside of the tube and  transfers the wire position to the precisely machined
reference surface at the outside of the tube  which is used to accurately position the drift tubes
during chamber assembly. The wire position information is transferred solely via the precision
machined brass insert; precision machining of the complete endplugs is not necessary anymore,
facilitating the production of the tubes and improving the accuracy of chamber construction. The
two most critical problems for the ATLAS MDT drift tube production, cracking of the
Noryl\textsuperscript{\textregistered} plastic insulator and precision machining of the injection
moulded endplugs, have been eliminated by the new design.      

The insulators of the endplugs consist of Crastin\textsuperscript{\textregistered}, a PBT based
thermoplastic with 30~\% glass fiber admixture to improve mechanical stability  which shows little
shrinkage and outgassing and, unlike Noryl\textsuperscript{\textregistered} (material in the
present MDT endplugs), high stability against cracking under stress. The material is of similar
chemical composition as Pocan\textsuperscript{\textregistered}  which is used for the injection
moulded components of the gas manifolds of the present and the new drift tube chambers.  The
endplugs are fabricated by injection moulding and sealed in the aluminum tubes with O-rings by
circular mechanical crimping  of the tube walls.   

% --- Fig.  5 ----------------------------------------------------------------
%
\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.7\linewidth,clip]{Figures/smdt_tube_design_3D} 
%
\caption{Exploded view of a drift tube with endplug and gas, signal and ground connections
\label{fig_smdt_tube_design}
% 
\end{center}
\end{figure}


% --- Fig.  6 ----------------------------------------------------------------
%

\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.8\linewidth,clip]{Figures/gasmanifold_design}

\caption{Design of the gas manifolds. The gas inlet and outlet bars are 
located at opposite ends of the tube multilayers.}
\label{fig_gasmanifold_design}
% 
\end{center}
\end{figure}


% --- Fig.  7 ----------------------------------------------------------------
%
\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.7\linewidth,clip]{Figures/gasmanifold_photo}
%
\caption{Picture of the gas manifold mounted on the prototype chamber.}
\label{fig_gasmanifold_photo}
% 
\end{center}
\end{figure}


The modular gas distribution system consists of injection moulded plastic tubes made of
Pocan\textsuperscript{\textregistered} without glass fiber which interconnect adjacent tubes in
the direction perpedicular to the multilayer and connect them to an aluminum gas distribution bar
on the readout and the high-voltage end of the multilayer (see Figs.~\ref{fig_gasmanifold_design}
and \ref{fig_gasmanifold_photo}). 

% --- Fig.  8 ----------------------------------------------------------------
%
\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.4\linewidth,clip]{Figures/hv_hedgehog}
\includegraphics[width=0.4\linewidth,clip]{Figures/signal_hedgehog}
%
\caption{High voltage (left) and signal distribution boards (right), 
the ''hedgehog cards'', to be mounted at the two ends of the tubes.}
\label{fig_hedgehogs}
% 
\end{center}
\end{figure}

The readout and high-voltage supply scheme follows closely the one of the present MDT chambers
using the same parameters and specifications. The high-voltage decoupling capacitors on the readout
side and the terminating resistors on the high-voltage supply end are individually encapsulated in
plastic containers for high-voltage protection. The plastic containers are integrated with the
hedgehog cards plugged onto the gold-plated pins of the signal caps and ground connectors. The
ground pins are screwed into the gaps formed by three adjacent tubes (see Figs.~\ref{fig_smdt_tube_design_3D} 
and \ref{fig_gasmanifold_photo). 
during chamber assembly to connect the tube walls to the ground of the hedgehog cards. This scheme
allows for the high-voltage-free design of the readout hedgehog cards. 

Each passive readout hedgehog card is connected to an active front end electronics board (mezzanine card) for 24 channels 
carrying new radiation hard ASICs, three 8-channel amplifier-shaper-discrimiator (ASD) chips and one 32-channel HPTDC chip 
(see below). The mezzanine cards follow one-to one the shape of the hedgehog cards and are already under development. The
electronics boards are enclosed in chromatized aluminum Faraday cages which also shield the readout hedgehog
cards from the mezzanine cards.  


%%% ==== B2.2 ============================================================
%%%

\subsection{Readout Electronics}
\label{readout_electronics}


The readout of the Small MDT tubes will follow the proven architecture of the present MDT
system. A number of additions and modifications, however, will be necessary in order to
adapt the rate capability of the readout chain to the requirements of the SLHC. For the
mechanical integration of the readout electronics with the Small tube chambers, the
layout of the electronics will have to be adapted to the 4 times higher tube density at
the ends of the Small tube chambers. Finally, the radiation tolerance of all components
will have to comply with the high radiation levels, in particular at the inner border of
the Small Wheel.


%% ----- 5.5.1-----------------------------------------------------------
%%
\subsubsection{Architecture of the present MDT readout}
\label{MDT_architecture}
%%
%% ----------------------------------------------------------------------

In the present readout scheme tube signals are routed via a PCB ("hedgehog card") to a
piggy-back card ("mezzanine card"), containing an Amplifier and Shaper, followed by a
Discriminator with adjustable threshold, all three functions being integrated in a
radiation tolerant ASIC (ASD). The discriminator outputs, in turn, are routed to a TDC,
where each leading and trailing edge signal receives a high-precision time stamp, which
is retained, together with the corresponding channel number, in a large internal buffer
of the TDC ("Level-1 buffer").

When the TDC receives a Level-1 trigger, a subset of the recorded hits, corresponding to
a pre-defined time window, are retained for readout and are forwarded to the data
concentrator of this chamber, the "Chamber Service Module" (CSM). From there, data are
sent to the off-chamber electronics in USA15, the "Readout Driver" (ROD). A CSM can
serve up to 18 mezzanine cards. The operation parameters of the analog frontend (ASD)
and the TDC are controlled by a JTAG string, which is distributed by the Detector
Control System (DCS) to the CSM, which sends it individually to each mezzanine card.
Fig.~\ref{readout_chain} gives the layout of the present system. A detailed presentation
of the MDT readout electronics is given in ~\cite{MDT_ELX_paper}. The ASD and TDC ASICs
are described in ~\cite{ASD_manual} and ~\cite{TDC_manual}.

%% Fig. 3 ---------------------------------------------------------------------------

\begin{figure}[!htb]
%
\begin{center}
%
\includegraphics[width=0.45\linewidth,clip]{Figures/MDT_electronics_scheme_old}
\hspace{5mm}
\includegraphics[width=0.39\linewidth,clip]{Figures/Elx_diagram_sm_tubes}

\caption{Schematic diagram of the present (left) and of the future MDT readout chain (right). The
Chamber Service Module (CSM) collects all data of a given chamber and sends them to the ROD via an
optical link. Up to 18 TDCs can be serviced by a CSM. The 40 MHz clock and the Level-1 trigger are
broadcast by the TTC system to the TDCs.}

\label{readout_chain}

\end{center}

\end{figure}


%% ----- 5.5.2-----------------------------------------------------------
%%
\subsubsection{Architecture of the readout for sMDT chambers}
\label{MDT_architecture_Small_tubes}
%%

For the evolution of this architecture into matching the requirements of the Small tube
readout, a number of problems limiting the performance of the present scheme has to be
overcome. Given the high rate capability of the Small MDT tubes, the bandwidth of the
readout system has to be increased. Due to the limitations of the internal buffering
scheme and processing speed, the present TDC can only handle average tube rates up to
about 300 kHz per tube without losing data, while Small tubes would operate beyond 1 MHz
per tube. Therefore, an improved TDC is an essential requirement for a new readout
design. Another limitation of the readout bandwidth comes from the optical link,
connecting the CSM to the ROD, as the S-link protocol only supports a usable bandwidth
of 1,4 Gbit/s. Fig.~\ref{occ_and_link} shows occupancy and efficiency of Large and Small
tubes as a function of tube hit rate.


\if{0}

%% Fig. 4 ---------------------------------------------------------------------------
%
\begin{figure}[!htb]
%
\begin{center}
%
\includegraphics[width=0.50\linewidth,clip]{Figures/Elx_diagram_sm_tubes}

\caption{Schematic diagram of the chain for the readout of the Small tube chambers. The
higher tube density at the tube ends requires a higher modularity for the readout architecture.}

\label{Elx_diagram_sm_tubes}

\end{center}

\end{figure}

\fi

%% ---------------------------------------------------------------------------------

When upgrading the performance of ASICs (ASD, TDC), we have to take into account that
their technologies are no longer supported by industry. The following new components had
therefore to be introduced into the readout system.

%% Fig. 4  -------------------------------------------------------------------------

\begin{figure}[!htb] 

\begin{center}

\includegraphics[width=0.5\linewidth,clip]{Figures/print_summary_15_08_2011}

\caption
{Three performance parameters for the 15 mm MDTs as a function of the tube hit rate. Red
curve: efficiency, assuming a dead time of 200 ns (equal to the maximum drift time) after
each hit. Blue: Saturation of the data link from TDC to CSM. Purple: Saturation of the
link from CSM to ROD. The links have a useful bandwidth of 80 Mbit/s and 1,4 Gbit/s,
respectively. Both have a base load of about 15\% due to the overhead of the transfer
protocol.
}

\label{occ_and_link}
\end{center}
\end{figure}

\begin{enumerate}

  \item[(a)] The ASD is re-designed in the IBM 130 nm technology. A 4-channel
  prototype, demonstrating the analog parameters, has already been produced and tested and works
  correctly. Most analog parameters of the previous design are preserved. 
  The 4-channel version of the complete ASD chip has been delivered and bonded 
  and is ready for testing.  

  \item[(b)] The TDC will be replaced by the HPTDC, designed by the CERN-MIC group
  (~\cite{The_HPTDC}). This 32-channel device has an improved internal buffering
  scheme as well as higher transfer and processing speeds.

  \item[(c)] The CSM collects data from a MDT chamber formats the event and sends
  data, trigger-by-trigger, via an optical link to the ROD in USA15. All logical
  operations are performed by an FPGA, which will need to be upgraded to higher
  radiation tolerance. The interface to DCS, needed for controlling electrical and
  temperature parameters on the chamber will be done via the GBT (see below). The
  adapter box to the CANbus (ELMB) can therefore be dropped, reducing complexity of
  cabling.

  \item[(d)] The link connecting the CSM to the ROD will be replaced by a GigaBit
  Transmitter link (GBT), developed by CERN. This link provides a 3 times higher
  transfer rate (Gbit/s), compared to the S-link~\cite{GBT}.  

\end{enumerate}

% -------------------------------------------------------------------------------

Another stringent requirement for the realization of the new readout scheme is
the mechanical integration of the on-chamber readout electronics with the chamber
mechanics, as the density of channels at the tube ends is four times higher than in the
case of the Large tubes. The following design changes will therefore be implemented.

\begin{enumerate}

  \item[(a)]
  HV decoupling capacitors are located in 15 mm diameter cylinders at the tube ends, see
  Fig.~\ref{fig_hedgehogs}. The density of signal routing on hedgehog cards
  is thus no longer limited by HV insulation distances between HV 
  and signal traces on the PCB. 

  \item[(b)] To match the higher tube density, the space on the mezzanine card has to be used
  more efficiently. For this purpose, the passive protection circuitry of the ASD inputs
  will be moved to the hedgehog card. In addition, the modularity of the ADSs will be
  changed from 8 to 16 channels per chip, which goes well with the 32-channel modularity
  of the HPTDC.  

  \item[(c)] For the interconnection between mezzanine cards and New CSM 
  we foresee to use the same 40-wire cables as was used in the present system. 
  Its moderate diameter and high flexibility may be important for fitting the new MDTs
  into the limited space in the Small Wheel.
  
\end{enumerate}


%%% ==== B3 ============================================================
%%%
\subsection{Chamber Construction}
\label{chamber_assembly}
%%%
%%% ====================================================================


{\it
  Describe the assembly procedure. Include details on
  \begin{enumerate}
  \item Achieved mechanical precision of signal generating parts
    (i.e. strips or wires)
  \item Speed of assembly
  \item Splitting of work and logistics between production site
  \end{enumerate}
}

%% ------- B3.1 -------------------------------------------------------------
%%
\subsubsection{Drift tube production}
\label{Production of the drift tubes}
%%
%% --------------------------------------------------------------------------

The drift tubes are fabricated and tested in a climatized clean room of class 10000 using a
semi-automated assembly station  (Fig.~\ref{fig_wiringline}). The wires are fed through the
tube by air flow without touching them by hand. Wire tensioning and
crimping is performed fully automatically. After fabrication, the tubes are immediately tested for
wire tension, gas tightness and leakage currents under high voltage (see below). 
A production speed of 120 drift tubes per day has already been achieved.

%% ------- B3.2 -------------------------------------------------------------
%%
\subsubsection{Chamber assembly}
\label{Precision_placement_of_tubes}
%%
%% --------------------------------------------------------------------------

The individual tubes are assembled to chambers using precision jigs on a flat granite table in a
climatized clean room as shown in Figs.~\ref{fig_jigging}. The jigs are
machined with an accuracy of $10~\mu$m. The two multilayers are assembled and glued together within
one working day using two identical jigs. The assembly procedure is illustrated in
Fig.~\ref{fig_prototype_assembly}. The jig elements positioning the endplugs
and sense wires of each layer in the transverse plane are stacked layer-by-layer forming a  precise
two-dimensional grid.  Bearings for mounting of the trigger chambers and, for the first multilayer,
platforms holding the external alignment sensors  are glued to the bottom tube layers positioning
them precisely with respect to the assembly jigs and, therefore, to the wires. 

% --- Fig. 30 ----------------------------------------------------------------
%
\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.55\linewidth,clip]{Figures/fig_wiringline}
%
\caption{Semi-automated drift tube assembly station.}
\label{fig_wiringline}
% 
\end{center}
\end{figure}

% --- Fig. 31 ----------------------------------------------------------------
%
\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.85\linewidth,clip]{Figures/jigging_BB}
%
\caption{Assembly tooling for the sMDT chambers with precise positioning of the endplugs
of the drift tubes holding the sense wires. The jigs are modular and adjustable for the 
construction of different chamber types. References for the precise mounting of the alignment 
sensor platforms with respect to the wires are part of the jig design.}
\label{fig_jigging}
% 
\end{center}
\end{figure}

On the second day, after letting the glue cure over night, the spacer frame is glued to the top of
the first multilayer in its jig and the in-plane alignment system is calibrated.   The second
multilayer is removed from the jig and glued to the top of the spacer, aligning it precisely with
respect to the assembly jig and thus to the first multilayer. Monitoring of the tube and layer
positions during chamber construction is not  necessary with this assembly scheme.    

After the assembly of the drift tubes, the mounting of the gas manifolds and testing for leak
tightness requires about one week. Another two weeks are foreseen for mounting of the hedgehog
cards, installation of the Faraday cages and cabling of the chamber. Mounting of the trigger
chambers on the drift tube chambers and combined test will be performed at CERN.  


% --- Fig. 33 ----------------------------------------------------------------
%
\begin{figure}[!htb]
\begin{center}
\includegraphics[width=0.5\linewidth,clip]{Figures/prototype_assembly1}
\includegraphics[width=0.5\linewidth,clip]{Figures/prototype_assembly2}
\label{fig_prototype_assembly}
%
\caption{The sMDT prototype chamber during and after assembly, consisting of two multilayers with 8 tube layers each, 
72 tubes per layer and 1152 tubes in total.}
%
\end{center}
\end{figure}
% ----------------------------------------------------------------------------


%% --------- B3.3 -----------------------------------------------------------
%%
\subsubsection{Prototype chamber construction}
\label{Prototype_production}
%%
%% --------------------------------------------------------------------------

A full-scale prototype of a 15~mm diameter drift tube chamber for the innermost region of the Small
Wheels presently covered by CSC chambers has been constructed in 2010 (see
Figs.~\ref{fig_prototype_assembly} and tested in the CERN Gamma Irradiation Facility GIF  as well
as in the H8 testbeam in 2010 and 2011. The chamber consists of 2 x 8 layers of drift tubes and is
readout with the existing MDT mezzanine cards and Chamber Service Module (CSM). With this prototype
chamber all aspects of the chamber design and performance as well as the construction
and test procedures have been verified and the required time and manpower for chamber production
and test has been evaluated in detail. With the semiautomated drift tube assembly facility, 100
drift tube can be routinely produced per day at each construction site.  The tubes assembled every
day will be tested for gas tightness and leakage currents under high voltage in automated test
stands over night. 

The wire positions in prototype chambers have been measured in the cosmic ray
test stand at LMU Munich with an accuracy of few microns. The measured wire grid agrees with the
expected grid to better than $20~\mu$m rms (Fig.~\ref{fig_wirepos}). 

% --- Fig. 34 ----------------------------------------------------------------
%
\begin{figure}[!htb] 
\begin{center}
\includegraphics[width=0.5\linewidth,clip]{Figures/wirepos}
%
\caption{The accuracy of wire positioning in prototype chambers is better than $20~\mu$m rms.}
\label{fig_wirepos}
% 
\end{center}
\end{figure}


%% --------- B3.4 -----------------------------------------------------------
%%
\subsubsection{Interfacing with the readout electronics}
\label{Interfacing}
%%
%% --------------------------------------------------------------------------

The readout and high-voltage supply scheme follows closely the one of the present MDT chambers
using the same parameters and specifications. The high-voltage decoupling capacitors on the readout
side and the terminating resistors on the high-voltage supply end are individually encapsulated in
plastic containers for high-voltage protection. The plastic containers are integrated with the
hedgehog cards plugged onto the gold-plated pins of the signal caps and ground connectors. The
ground pins are screwed into the gaps formed by three adjacent tubes 
%% (see Fig.~\ref{fig_groundpin})
during chamber assembly to connect the tube walls to the ground of the hedgehog cards
(Fig.~\ref{fig_hedgehogs}. This scheme allows for the high-voltage-free design of the readout
hedgehog cards. 

Each passive readout hedgehog card is connected to an active front end electronics board (mezzanine
card) for 24 channels  carrying new radiation hard ASICs, three 8-channel
amplifier-shaper-discrimiator (ASD) chips and one 32-channel HPTDC chip  (see below). The mezzanine
cards follow one-to one the shape of the hedgehog cards and are already under development. The
electronics boards are enclosed in chromatized aluminum Faraday cages which also shield the readout
hedgehog cards against the mezzanine cards.  


%% Fig. 22  %%%%%%%%%%%%

\begin{figure}[!htb]
\begin{center}
\vspace{5mm}

\includegraphics[width=0.38\linewidth,clip]{Figures/hv_hedgehog}
\includegraphics[width=0.38\linewidth,clip]{Figures/signal_hedgehog}
\includegraphics[width=0.25\linewidth,clip]{Figures/Small_tubes_w_elx} 
%
\caption{High voltage (left) and signal (middle) distribution boards,
the ''hedgehog cards'', to be mounted at the two ends of the tubes (right).
The plastic cylinders containing the decoupling capacitors and the terminating resistors, respectively,
are integrated on the PCB boards.}
\label{fig_hedgehogs}
%
\end{center}

\end{figure}

%%%%%%%%%%%%%%%%%%%%%%%%




%% ---------- B3.4 ----------------------------------------------------------
%%
\subsubsection{Sharing of work and logistics between production sites}
\label{Splitting_of_work}
%%
%% --------------------------------------------------------------------------

The construction of the 96 drift tube chambers with approximately 70000 drift tubes of lengths
between 0.5~m and 2.2~m for the new Small Wheels can be performed at two main construction sites, the MPI
Munich and the University of Freiburg, in the years 2013 to 2016. 
The intergration of the drift tube and trigger chambers at CERN will proceed in parallel. 

LMU Munich and the University of W\"urzburg will contribute to the testing of drift tubes and
completed chambers before and after shipment to CERN as well as to chamber integration and
commissioning of the Small Wheels at CERN. The relative wire positions of all chambers will be
measured with an accuracy of about 10 $\mu m$ in the cosmic ray test stand at LMU Munich like for
the BOS and BOF MDT chambers in ATLAS. With additional institutions joining the project, the
chamber construction can proceed faster. 2-3 FTE manpower per construction site are planned for the
chamber construction. 

The participating institutes have extensive experience with the construction of the ATLAS MDT
chambers as well as the associated quality assurance procedures. The required clean rooms and test
equipment and the design of tooling for chamber construction and testing already exist. The
University of Freiburg and MPI Munich will also be involved in the design, fabrication and
measurement of the alignment reference bars for the new Small Wheels in collaboration with Brandeis
University.


%%% ==== B4 ============================================================
%%%
\subsection{Quality Assurance and Commissioning}
\label{Quality_Assurance}
%%%
%%% ====================================================================

\if{0}

{\it

  \begin{enumerate}
  \item Quality assurance of all individual chamber parts, include
    necessary manpower and rate of tests
  \item Quality assurance and commissioning scheme of full chambers,
    include necessary manpower and rate of tests
  \item How can/is data of the commissioning used later (e.g. strip or
    wire positions)?
  \end{enumerate}

  Note: A common commissioning strategy during and after assembly of
  the wheels will be given in a previous chapter
}

\fi

The quality assurance and commissioning procedures follow closely the specifications for the MDT
chamber production for the ATLAS muon spectrometer~\cite{ref_qadoc}. Each tubes will be tested for
wire tension, gas tightness and leakage currents under high voltage before installation in a
chamber. Wire position measurement for individual drift tubes is no more necessary due to the new
endplug design (see~\ref{chamber_assembly}. Monitoring of the tube positioning in the chamber
during assembly has also become unnecessary. 

The hedgehog cards and the mezzanine readout boards with the new radiation hard ASD and HPTDC chips
as well as the new chamber service modules CSM (see below) will be desiged, produced and tested by
MPI Munich.  New improved noise filters for the high-voltage supply lines for each chamber layer
have been designed and will be produced at MPI Munich.

The completed chambers will be tested for broken wires, gas tightness, leakage currents and noise
rate before and after delivery to CERN. In addition, all chambers will be tested in the cosmic ray
test stand at LMU Munich and their relative wire positions will be measured with an accuracy of
about 10 $\mu m$ as was done for the BOS and BOF chambers. 

After the integration of trigger and drift-tube chambers a measurement of the relative positions of
strips in the trigger chamber with respect to the wires in the drift tube chambers is foreseen. The
full quality control procedures have already been developed during the prototype chamber
construction. 

2-3 FTE manpower at each of the 4 core production sites are planned for chamber testing and
commissioning.   


%%% ==== B5 ============================================================
%%%
\subsection{Operation, Maintenance and Safety}
\label{Operation}
%%%
%%% ====================================================================

\if{0}

{\it

  Describe in detail the impact of failures of single components (gas
  leak, HV breakdown, front-end electronics) on the 
  detector operation. Comment on possible built-in redundancy.\\

  Describe in detail the possible scenarios for maintenance on the
  detector and the exchange or repair of detector parts.\\

  Describe the risks associated with the technology during operation
  and maintenance (HV, maximum currents, flammable gas etc.)

}
\fi

Due to their robust design and the high quality assurance standards during construction and
commissioning, the ATLAS MDT chambers operate with very high reliability and data taking
efficiency. The same design, fabrication and testing procedures will be applied for the small
diameter drift tube chambers. Also maintenance and repair procedures will be the same in principle
as for the existing MDT chamber system with improvements in the access to the CSMs and the HV splitter boxes
as well as to the chambers in the inner regions of the new Small Wheels. 

The modular structure of the chambers provides a high degree of redundancy.
Each multilayer of a chamber will be supplied by a separate high voltage channel,
the innermost chambers by two channels because of the higher currents. 
384 HV channels are needed for both Small Wheels. 

In the chamber layout and the design of the Small Wheel structure, accessibility
of the Faraday cages of the drift tube chambers for exchange of electronics boards 
or for disconnecting individual drift tubes has been taken into account. 
The chamber service modules (CSM) together with the DCS boxes of all chambers will be installed in
better accessible and more radiation-safe regions at the outer rim of the Small Wheel.
There will be 2 CSMs per chamber, one per multilayer, such that only one multilayer is lost
until a broken CSM is replaced during an ultrashort access. 

The individual tube layers are independently connected to the high-voltage. 
The splitter boxes for the HV channels will be located at the outer rim of the new Small Wheels. 
If a wire breaks, which is a very rare event, only one tube layer will be lost after disconnecting it 
from the HV splitter in an ultrashort access. During winter shutdown and opening of the Small Wheel, 
the affected tube can be disconnected from the high-voltage and the rest of the tube layer can be reconnected.

Gas leaks in the present MDT chambers are mainly due to cracks in injection moulded Noryl\textsuperscript{\textregistered}
endplugs and gas connectors. The drift tubes in the new Small Wheels are mechanically 
protected from the outside by the trigger chambers. To avoid gas leaks due to cracks in
endplug insulators and gas connectors, thermoplastics with much better robustness against cracking
than in te present MDT chambers have been chosen (see~\ref{Technical_Implementation}, above). 
In addition due to their smaller volume, the 15~mm diameter endplugs are less prone to mechanical stress and cracks in the
injection moulded plastic insulators than the 30~mm diameter endplugs.

The existing recirculating gas system with one volume exchange per day can be fully re-used. 
Each multilayer of a Small Wheel sector will be supplied separately with gas using 16 gas lines
for each new Small Wheel. Each multilayer of a chamber has a valve located at the outer rim of the Small Wheel.
The total gas volume of the sMDT chambers in one new Small Wheel is 6750~l, 4000~l less than for the
MDT chambers in one present Small Wheel. 

The risk assessment for the sMDT chamber system for the new Small Wheels is summarized in Table~\ref{riskanalysis} 
including the measures for minimizing the risk and reducing it even further than in the present Small Wheels.

%
\begin{table}[!htb]

  \begin{center}
%   
    \begin{tabular}{|l|l|l|l|} \hline 

    Component              & Comment                    & Loss in coverage &  Recovery procedure  \\  
                           & (redundancy, accessibility)&                  &                      \\     
   \hline 
    CSM (with DCS box)     & 2 CSMs per chamber,        & 1 multilayer     & Repair in ultrashort access \\   
                           & 1 CSM per multilayer (ML), &   
                           & CSMs loc. at SW outer rim  &
    \hline 
    Mezzanine card         &                            & 24 channels in one ML & Repair in winter shutdown \\
    \hline
    LV power supplies      & 2 CSMs (in diff. chambers) & 2 ML in diff. chambers & Repair in ultrashort access \\        
                           & per channel                &  
    \hline 
    HV power supplies      & $1-2$ channels per ML      & $0.5-1$ ML              & Repair in ultrashort access \\
    \hline
    Broken wire            & HV distr.\ layer by layer, & $0.5-1$ ML before,                 & Disconnect tube layer       \\  
                           & splitters at SW outer rim, & $0.5-1$ layer after layer disc.    & in ultrashort access.       \\       
                           & rare event                 & 1 tube                             & Disconnect tube from HV     \\
                           &                            &                                    & in winter shutdown.         \\
   \hline
    Gas leaks              & 1 gas line per sector and ML,  & 1 ML of 1 sector before, & Close valve of leaking ML \\  
                           & 1 valve per ML at SW outer rim & 1 ML of 1 chamber after  & in ultrashort access.     \\
                           &                                & closing valve.           & Repair in winter shutdown. \\
   \hline
   \end{tabular}
   \caption{Risk analysis for the sMDT system in the new Small Wheels. The redundancy and accesibility of the critical components 
            and the maximum loss in detector coverage
            in case of failure of one of the components are given as well as the recovery procedures.\label{riskanalysis}}
  \end{center}
%
\end{table}

 

%%% ==== B6 ============================================================
%%%
\subsection{Detector Performance}
\label{Performance_appendix}
%%%
%%% ====================================================================

\if{0}

{\it
  Describe in detail the performance of the detector, including
  results from test beam studies. Include studies with background
  radiation ($\gamma$, n, p)

  \begin{enumerate}
  \item Detector occupancy as function of rate
  \item Spatial and angular resolution as functions of rate and angle
    of incidence for single point measurements and segments
  \item Time resolution
  \item Efficiency (single measurement and segment)
  \item Double track resolution
  \item Rejection of fake and background tracks
  \item Sensitivity to background radiation
  \item Performance limits (maximum rate)
  \end{enumerate}
}
\fi

In order to verify the performance of the 15 mm (''small'') diameter drift tube chambers, extensive
tests of the full-scale prototype chamber with 15~mm diameter drift tubes have been
performed in 2010 and 2011 in the H8 high-energy muon beam 
(see Fig.~\ref{fig_prototype_H8}, left) and, using cosmic ray muon tracks, in the
CERN Gamma Irradiation Facility (GIF) with a 500~GBq ${}^{137}$Cs source
(Fig.~\ref{fig_prototype_H8}, right). Standard ATLAS MDT readout electronics has been used
with the adjustable deadtime set to the minimum value corresponding to an overall effective
deadtime of 200~ns. The spatial resolution and the efficiency of the individual drift tubes 
have been measured for increasing $\gamma$ background counting rates up to 1200 kHz/tube 
at uniform illumination corresponding to 17~kHz/cm$^2$ in tubes of 0.5~m length like at the 
innermost radius of the new Small Wheels. 

% --- Fig. 35 ----------------------------------------------------------------
%
\begin{figure}[ht] 
\begin{center}
\includegraphics[width=0.5\linewidth,clip]{Figures/H8_photo} 
\hspace{5mm}
\includegraphics[width=0.5\linewidth,clip]{Figures/GIF_drawing} 
%
\caption{The test setups with the sMDT prototype chamber in the H8 muon beam at CERN (left) and in the GIF 
using a cosmic ray muon trigger (right).} 
\label{fig_prototype_H8}
% 
\end{center}
\end{figure}

As a measure for evaluating the tracking efficiency, we define the ''3$\sigma$-efficiency'' as the
probability of detecting a tube hit within a distance of 3 times the drift tube resolution $\sigma$
from the muon track, the muon track being defined by the other tubes on the track, extrapolated to
the active volume of the tube. Similarly, the drift tube resolution as a function of the drift  
radius is determined by an iterative method excluding the evaluated tube from the track
reconstruction in the chamber~\cite{ref_resolution_measurement}. 


% --- Fig. 36 ----------------------------------------------------------------
%
\begin{figure}[ht] 
\begin{center}
\includegraphics[width=0.5\linewidth,clip]{Figures/efficiency_vs_flux} 
%
\caption{The $3\sigma$ efficiency of individual drift tubes as a function of the background hit rate as measured at the GIF.
Results for 15~mm and 30~mm diameter tubes are compared. The corresponding track segment reconstruction efficiencies in 2 x 4 layer 
MDT chambers and 2 x 6 layer sMDT chambers are indicated as dashed curves and have been calculated from the tube efficiencies 
requiring at least two hits in each multilayer.}
\label{fig_efficiency_GIF11}
% 
\end{center}
\end{figure}



Fig.~\ref{fig_efficiency_GIF11} shows the 3-$\sigma$ efficiency of 15~mm diameter drift
tubes and the track segment reconstruction efficiency as a function of the
$\gamma$ background flux in comparison with the results for the 30~mm diameter tubes from previous
tests of a BOS MDT chamber at GIF with the X5 muon beam~\cite{ref_deile}, \cite{ref_horvat}.  
The measurements were performed using as 
external tracking reference the other drift tube layers of the prototype chamber vs.\ a
silicon strip detector beam telescope for the BOS chamber in the X5 beam.
At low background rates, the
$3\sigma$ tube  efficiencies of 30 and 15~mm diameter tubes are 94~\% and 96~\%, respectively. The
efficiency loss is due to $\delta$-rays created by interaction of the muons with the tube walls
which produce hits earlier than the muons. The degradation of the efficiency with increasing rate
follows the expected linear behaviour. The redundancy of track measurements in different tube
layers allows for more the 99~\% track segment reconstruction efficiency up to background rates
well beyond the highest expectations at inner radius of the Small Wheels at Super-LHC.  

% --- Fig. 16 ----------------------------------------------------------------
%
\begin{figure}[ht] 
\begin{center}
\includegraphics[width=0.5\linewidth,clip]{Figures/resolution_measured_vs_simulated} 
%
\caption{Spatial resolution of large and small tubes in the H8 test beam together with simulation
results.}
\label{fig_resolution_H8_rdep}
% 
\end{center}
\end{figure}
%

In Fig.~\ref{fig_resolution_H8_rdep} the spatial resolutions of 15~mm and 30~mm diameter drift
tubes  measured as a function of the drift radius $r$ without background irradiation 
in the high-energy muon beams H8 and X5 at CERN,
respectively, are compared. The radial dependence of the 15~mm diameter
tube resolution agrees with the 30~mm diameter tube resolution measurement for $r<7.5$~mm as
expected. The average resolutions including time-slewing corrections  of 15 and 30~mm diameter
tubes at low background rates are $110\pm 10~\mu$m and $80\pm 5~\mu$m, respectively. 


\subsection{Aging Tests}

{\it

  Describe in detail results from aging tests for all components, the
  detector itself including the on-chamber gas distribution, read-out
  and/or trigger, alignment, and detector control electronics.

}

No aging is expected to occur in aluminum drift tubes with clean Ar:CO$_2$ gas. 
No aging has been observed in test of the MDT tubes up to a collected charge 
on the wire of 0.6~C/cm. Endplug and gas system materials with little outgassing which have 
already been certified for the ATLAS MDT chambers are used and strict cleaning procedures are applied 
for all components in order to prevent contamination of the drift gas. 

Long-term aging tests of the new drift tubes up to 2-3 C/cm collected charge including irradiation
of the endplugs are ongoing with intense radioactive sources at LMU Munich. 

\subsection{Cost, Funding, and Manpower}

\if{0}

{\it

  \begin{enumerate}
  \item Table of cost of each component, full chambers and total
  \item Additional costs (e.g. integrating two technologies)
  \item Arrangements for funding (if any so far)  
  \item List of manpower needs, especially include statements on the
    the current and future availability of experts (for at least the
    full construction and commissioning period, i.e. 2012 -- 2019,
    better also for the operation)
  \end{enumerate}
    
}
\fi

The costs of chamber mechanical components, on-chamber electronics, power supplies and DAQ system 
are summarized in Table~\ref{sMDT_cost}. The cost estimates are based on tenders as well as on the actual cost 
figures of the ATLAS MDT chamber components. 

Manpower cost for chamber assembly and test and for the testing of the electronics boards is not included
The manpower allocation foreseen for this work at the participating institutes is shown in Table~\ref{sMDT_manpower}.
The infrastructure of climatized clean rooms and the cosmic ray chamber test facility already exist
as well es experienced technical personell. The design of the chambers and of the assembly tooling is performed at MPI Munich.
The signal and high-voltage distribution (hedgehog) boards, the readout (mezzanine) cards,
the amplifier-shaper-discriminator (ASD) chip and the chamber service module (CSM) are already under development 
at MPI. 

A close collaboration exists between the MDT institutes and the TGC as well as the RPC institutes on
integrated chamber design and layout and on a common test program at the GIF and the H8 test beam.  
    
%
\begin{table}[!htb]

  \begin{center}
%   
    \begin{tabular}{|l|c|c|c|r|} \hline 

    Component & Number units & Cost/unit (CHF) & Total cost (kCHF)  \\  \hline

    Al tubes               &  71000 & 3.6     &   256 \\
    Wire                   & 5.5~km & 488/km  &     3 \\
    Endplugs               & 141312 & 5.6     &   791 \\
    Gas connectors         & 141312 & 0.8     &   113 \\
    Spacer, supports       &     96           &  1000   &   96 \\    
    Faraday cages          &   2 x 96         &   500   &   96 \\                     
    Tooling                &     2            & 25000   &   50 \\ 
   \hline
    Detector mechanics     & \multicolumn{2}{|c|}{} & 1405 \\
   \hline

    HV\&RO hedgehog boards   & 5888 & 100 & 589 \\
    Mezzanine cards w. cable & 2944 & 240 & 706 \\ 
    CSMs                     & 160+32  & 1100& 211 \\
    MRODs/CSM                & 160 & 1200 & 192 \\   
   \hline
    Electronics\& readout    & \multicolumn{2}{|c|}{} & 1698 \\
   \hline

    Gas distribution system/ML &   2 x 96       &  300    &   58 \\
    LV\&HV power supplies      & 160            & 2000    &  320 \\ 
    w. cables/CSM              & & & \\
    DCS modules w.\ fiber link/CSM & 160  & 400 &  64 \\
   \hline
    Services       & \multicolumn{2}{|c|}{} & 442 \\
   \hline
    In-plane sensors/chamber   &     96          &  909    &   87 \\
    External alignment sensors &   4 x 96        &  455    &  175 \\
    Multiplexers/chamber       &     96          &  455    &   44 \\   
   \hline
    Alignment (on-chamber)     & \multicolumn{2}{|c|}{} & 306 \\ 
   \hline\hline
    Total          & \multicolumn{2}{|c|}{} & 3851 \\
   \hline 
    \end{tabular}
   \caption{CORE cost of the sMDT chamber system including services, readout and alignment components.\label{sMDT_cost}}
  \end{center}
%
\end{table}

%
\begin{table}[!htb]

  \begin{center}
%   
    \begin{tabular}{|l|c|c|c|c|c|c|c|c|} \hline 

    Cost (kCHF)            & 2012 & 2013 &  2014 & 2015 & 2016 & 2017 & 2018 & Total \\  \hline

    Detector mechanics     &  100 &  400 &   500 &  405 &      &      &      & 1405 \\

    Electronics\& readout  &      &  200 &   400 &  500 &  406 &  192 &      & 1698  \\

    Services               &      &      &       &   64 &  150 &  228 &      &  442  \\
                            
    Alignment (on-chamber) &      &   70 &    80 &   80 &   76 &      &      &  306  \\  

   \hline
    Total                  &  100 &  670 &   980 & 1049 &  632 &  420 &      & 3851  \\
   \hline 
    \end{tabular}
   \caption{CORE cost time profile for the sMDT chambers.\label{sMDT_cost}}
  \end{center}
%
\end{table}

\begin{table}[!htb]

  \begin{center}
%   
    \begin{tabular}{|l|c|l|} \hline 

    Institute & FTE & Contribution  \\  \hline

    MPI Munich    & 5    & Mechanics, electronics, L1 trigger design \\
                  & 7    & Chamber construction, test, integration, installation, \\
                  &      & alignment system, electronics production, HV/LV system \\   
    LMU Munich    & 3-4  & Chamber construction, test, integration, installation \\
    Freiburg U.   & 5-6  & Chamber construction, test, integration, installation, \\
                  &      & gas system, DCS, alignment system \\      
    W\"urzburg U. & 3    & Chamber, electronics test, integration, installation, \\
                  &      & HV/LV system \\ 
    IHEP Protvino &      & Chamber construction, test, installation \\ 
    NIKHEF        &      & MRODs design, production, test, installation \\
    Tokyo         &      & L1 trigger and electronics design and implementation \\
    Brandeis U.   &      & Alignment system \\
      
   \hline 
    \end{tabular}
   \caption{Manpower for sMDT design, production, integration and installation.\label{sMDT_manpower}}
  \end{center}
%
\end{table}

\begin{table}[!htb]

  \begin{center}
%   
   \begin{tabular}{|l|l|} \hline 
   
   Time of completion & Task \\

   2010 & sMDT Chamber design, prototype construction and test \\
   2011 & Integration sMDT amd trigger chambers, \\
        & full ASD FE chip (4 channels) \\
   2012 & Construction of sMDT chambers for elevator regions, \\
        & NSW design and chamber layout, \\ 
        & full 8-channel ASD chip \\
   2014 & CSM design incl. MDT based L1 trigger functionality \\ 
   2013--16 & Chamber construction and integration, electronics production \\
   2017--18 & Integration and installation of NSWs at CERN \\
     
   \hline 
   \end{tabular}
   \caption{Time schedule for sMDT chamber develoment amd construction.\label{sMDT_schedule}}
  \end{center}
%
\end{table}


It is planned to finance the complete sMDT system from funds by the German  
funding agency BMBF and by MPI Munich in the period 2012--2016.
In addition, NIKHEF has expressed interest to contribute the MRODs.
Brandeis University and the University of Freiburg plan to contribute the
optical alignment system including the alignment reference bars.   
The time schedule is shown in Table~\ref{sMDT_schedule}.

\if{0}

%
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% ---------------------------------------------------------------------------- %

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% ---------------------------------------------------------------------------- %

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% ---------------------------------------------------------------------------- %

\bibitem{Cavern_Background}
P. Barrow, G. Conti, M. Franklin and L. Jeanty,
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\relax
% ---------------------------------------------------------------------------- %

\bibitem{mdt_highrates}
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Instrumentation, Vienna, Austria,
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Magnetic Fields},
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% ---------------------------------------------------------------------------- %

\bibitem{ref_deile}
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% ---------------------------------------------------------------------------- %
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% ---------------------------------------------------------------------------- %
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%----------------------------------------------------------------------------- %
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%----------------------------------------------------------------------------- %
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%----------------------------------------------------------------------------- %
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%----------------------------------------------------------------------------- %
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%----------------------------------------------------------------------------- %
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%----------------------------------------------------------------------------- %
%
\end{thebibliography}


\fi

%
%% \end{document}
