%%%%%  The following statement gives section #5 to the MDT-TGC,
%%%%%  independent of the number of previous sections
%
\setcounter{section}{4}
%
\section{Detector concept 1 :  MDT + TGC  (working title)}

{\it Introduction to this concept:
This section should describe the technology concept, details 
up to the level of a single chamber should be given in the appropriate
appendix.}

\subsection{Introduction}

The Small Wheel (SW) is the first station (''Inner station'') in the end-cap of the
Muon spectrometer. Together with the Middle and Outer station it delivers the spatial
coordinates for the momentum determination of charged tracks. Between the Small Wheel
and the Middle station (''Big Wheel'') a toroidal magnet is located with a bending
power ranging from 3--7 T $\times$ m, depending on $\eta$, allowing a determination
of the track momentum with high accuracy.

Designed to measure the momentum of a charged particle, the three stations of the
end-cap have two distinct functions. They provide a fast, raw determination of the
transverse momentum p$_T$, shortly after the passage of the particle, to be used by
the Level-1 (L1) trigger. The L1 trigger logic has the task to identify events of
physics interest, for which a high-p$_T$ muon is a crucial signature. 

When a L1 trigger decision is broadcast to the ATLAS subsystems, the DAQ has to
retain all relevant information for the corresponding beam crossing (BX). Because of
technical limitations on data storage of the electronics, however, the L1-trigger
must arrive at the subdetectors not later than 2,5 $\mu$s after particle passage,
otherwise the information might be lost (trigger ''latency''). This short L1 trigger
latency of the present ATLAS readout system strongly limits the selectivity of the L1
decision, as only a fraction of the available tracking information can be used for a
reduction of fake triggers, which are mainly due to low-p$_T$ tracks. One of the
design aims for the ATLAS upgrade in phase II is an increase of the L1 trigger
latency to 6,4 $\mu$s or even up to 10 $\mu$s. At this point more selective trigger
strategies can be implemented, partly at the level of the frontend electronics,
partly at the level of the Central Trigger Processor (CTP), where trigger information
from different subdetectors can be combined.

The second important function of the three stations in the muon end-cap is the
measurement of the momentum with the highest available spatial accuracy. This is
achieved by combining high resolution drift tube chambers with a precise optical
alignment system. The relative positions of track hits in front and behind the
bending magnet are thus precisely known, resulting in the required momentum
resolution.

In the present Small Wheel Thin Gap Chambers (TGC) are used for the selection of
high-$p_T$ tracks for the L1-trigger, while Monitored Drift Tube chambers (MDT) are
used for the precision determination of the track  coordinates.

The LHC upgrade in phase I and II will lead to an increase of the instantaneous
luminosity by a factor of 2 (respectively 5). In the present SW, these
high luminosities and the resulting background rates of will lead to an
unacceptable reduction in trigger and tracking efficiency. In the following we
present a overview of the main shortcomings of the existing SW.

\subsubsection{Problems of Small Wheel chambers at high background}

The present L1-trigger in the end-cap suffers from the fact that a majority of tracks
crossing the SW do not come from the primary vertex and should therefore not be used
as parts of a high-p$_T$ muon candidates by the triggering system. The present
trigger does not allow not to determine the slope of the candidate track and can not
discard tracks which do not come from the primary vertex. Newly designed trigger
chambers will have to be able to determine the slope of the track with an accuracy of
$<$ 1 mrad in the r-z plane (bending plane). The slope must also be determined in the
$\phi$ direction, though with less accuracy, to further reduce the number of trigger
candidates which do not come from the interaction point.

The MDT precision chambers will start to lose efficiency if hit rates go beyond about
300 kHz per tube. The large majority of hits in the MDT are coming from gamma
and neutron conversions in support structures, tube walls, chamber gas and tungsten
wires. With a diameter of 30 mm and a length of 60--250 cm (??), MDT chambers see hit
rates of up to 300 kHz per tube, which comes close to what the readout system can
handle without losses. While the length of the tubes in the trapezoidal geometry of
the SW decreases proportional to r, the BG rates increase considerably faster than
with 1/r. Thus the highest hit rates per tube occur at the inner tip of of the EIS
and EIL chambers.

\begin{table}[ht!]   %%% Table:  1
%
\centering
%	
\begin{tabular}{|l||c|c|c|c|c|c|} \hline 
%    \cline{2-5} 
										 
  Chamber& location& tube    & expected      & rate per  & occup-   & effi-  \\  
%\hline   
  Type   & in r    & length  & hit rate      & tube      & ancy     & ciency \\  
\hline 
         & {\it cm}& {\it cm}& {\it hits/cm$^{2}$}& {\it kHz}& {\it \%} & {\it \%} \\  
\hline
  EIL0 & 150 cm  &   75 cm ?? & 2000  &  2 kHz    & 85 \% & xx \\
  EIL1 & 262 cm  &  152 cm    &  300  &  0,3 kHz  & 92 \% & xx \\
  EIL2 & 373 cm  &  206 cm    &  100  &  0,1 kHz  & 98 \% & xx \\ \hline
  \end{tabular}
  \caption{Expected hit rates and efficiencies for 15 mm tubes in the NSW.
          (Numbers are mostly dummies and have to be worked out later!}
  \label{NSW_efficiencies}
\end{table}

High hit occupancies of the tubes lead to inefficiencies due to the reduction of the
drift field and to space charge effects. In addition, the dead time induced into the
electronics by a conversion hit may mask a subsequent ''good'' hit from a track.

Table~\ref{NSW_efficiencies} gives background rates, occupancies and hit efficiencies
for MDT tubes at different radii in the SW, based on simulation work in
Ref.~\cite{RTF_rad_task_force}. Results form LHC running at luminosities up to $5
\times 10^{32}$ seem to indicate rates which are about a factor 3--4 above the
simulated ones for the innermost chambers EIS1 and EIL1 of the SW.

\subsubsection{Concept for a New Small Wheel}

Tu cure the shortcomings of the existing system, a new concept is proposed for the
Inner station, the New Small Wheel (NSW). For the trigger chambers we propose to
maintain the basic operating concept of TGC chambers, complementing them with a new,
high-performance readout system.  The pulseheight distribution of signals induced
into the strips of the TGC cathodes (measuring $\eta$) are convoluted to give the
precision coordinate with an accuracy of $ < $100 $\mu m$. With modern,
radiation-tolerant FPGAs the location of the hits can be determined fast enough for
the L1 trigger. In the proposed detector layout, a package of 4 TGC chambers is
placed in front and behind the MDT chambers, each. A TGC package will contain 4 wire
layers (wires running radially, perpendicular to the strips), 4 cathode layers for
centroide finding and another 4 cathode layers segmented into pads for fast selection
of a Region of Interest (RoI). In the offline analysis the pads will be an important
tool for resolving ambiguities in the x-y pairing of coordinates, when more than one
track is present in a chamber. With a distance of about 300 mm between the TGC
packages in front and behind the MDT, an angular resolution of $< 0,3$ mrad can be
achieved. Only tracks pointing to the interaction point will be considered as
high-p$_T$ candidates for the L1 trigger. A detailed presentation of the method is
given in section~\ref{chapter:TGC}.

The problem of high tube occupancies of the MDT is solved by using a newly developed
type of MDT drift tubes, the tube diameter being reduced from 30 mm to 15 mm. While
the tube area exposed to background radiation is thus reduced by a factor of two, the
maximum drift time is reduced by a factor of 3,5 (750 ns to 200 ns), the combined
effect giving a reduction of hit rates by a factor of 7. The mechanical structure and
the alignment system will be as similar as possible to the ones in the present SW
architecture. Like in the case of the TGCs, faster readout electronics has to be installed, see
section~\ref{chapter:MDT_electronics}.

Both new chamber systems, the TGCs and the MDTs, can be operated with the same
chamber gas as in the present system. Power requirements for the electronics of both
systems will be higher due to higher channel count. Whether this requires active
cooling, as is now used in the region $\eta$ $>$ 2 (''CSC region'') is under
study. Aim is to have services arranged in such a way as to be able to use the
existing service infrastructure like e.g. the cable Schlepps.

\subsection{Detector technology and layout}

{\it
    Description of detector concept (a detailed description of the
    working principle of each detector should be given as an
    appendix).\\
    If more than 1 technology is used motivate the decision and detail
    how they work together (e.g.\ can services be shared, is the
    information of the trigger chambers used in the precision
    chambers, how are combined chambers assembled etc.)
	
    List of all operating parameters\\
    Detailed layout: acceptance, description of chamber overlap
    and dead areas, drawings\\ 
    Tables with chambers sizes, number of channels\\
    Internal alignment scheme (the overall common endcap alignment scheme
    is described in the previous chapter)\\
    Calculations about mechanical stability and expected
    deformations due to gravity, temperature changes, (magnetic field) etc.\\
    Requirements for mount points\\
    Details of service points and other positions where access is needed\\
    Concept for chamber replacement (what needs to be dismounted etc.)
}


\subsubsection{Upgrade of the LHC towards higher Luminosities}
% ========================================================================================
%

For use at the future Super-LHC a new type of muon detector has been developed. It is based on 
the proven MDT drift tube design, but with tubes of half the diameter, leading to 
higher rate capabilities by an order of magnitude. 
We present test results on efficiency and position resolution at 
high background rates and describe the practical implementation in a real-size prototype. 

%~\ref{Large_small_tubes}).

% --- Fig.  1 -------------------------------------------------------------------------------
%
\begin{figure}[h]
\begin{center}
\includegraphics[width=0.4\linewidth,clip]{Figures/Large_small_tubes}
\label{Large_small_tubes}
%

\caption
{The tracking quality in 30 mm and 15 mm drift tubes in a region of high n/$\gamma$
background.
The occupancies from background hits (red dots) are 50\% in
the 30 mm tubes but only 7\% in the 15 mm tubes due to shorter drift time and smaller 
area.
}
%
\end{center}
\end{figure}
%

At luminosities far beyond the original design value of 10$^{34}$~cm$^{-2}$s$^{-1}$ 
the MDT drift tube chambers
will face the challenge to maintain excellent tracking efficiency in the
presence of high background hit rates, due to gamma conversions.

% ========================================================================================
\subsubsection{Tracking in a high--back\-ground environment}
% ========================================================================================
%

The outer region of the ATLAS detector,  where the muon chambers are located, receives high rates
of low-energy neutrons,  mainly due to shower leakage from calorimeters and shielding structures in
the high-$\eta$ region.  At the nominal luminosity, gammas from neutron capture and related
conversion electrons are expected to generate hit rates in the range 50--300 kHz in each MDT tube.
A conversion electron may create an inefficiency if the signal arrives {\it before} the muon
signal. The muon detection efficiency thus becomes exp(-$\tau\times$f) $\approx$ 1-$\tau\times$f, 
where $\tau$ is the average drift time in the MDT tubes and f the hit rate due to gamma
conversions.

%\ref{Large_small_efficiency} 
%
% --- Fig.  2 -------------------------------------------------------------------------------
\begin{figure}[h]
\begin{center}
\includegraphics[width=0.4\linewidth,clip]{Figures/Large_small_efficiency}
%
\caption{Efficiency vs. hit rate per tube for 30 mm and 15 mm drift tubes.}
\label{Large_small_efficiency}
%
\end{center}
\end{figure}
% -------------------------------------------------------------------------------------------

At high rates of n/$\gamma$ background, the efficiency may be further reduced by a decrease of the
gas amplification due to space charge from slowly drifting positive ions in the tubes,
while the {\it fluctuations} of the space charge tend to degrade the spatial resolution by up to 
about 20 \% at the highest rates. 

The effects of gamma conversions in the MDT tubes have been studied in detail using a muon beam in
the presence of intense $\gamma$-irradiation of up to $500\,$Hz/cm$^{2}$ (i.e. $\sim$300 kHz/tube),
as delivered by the Gamma Irradiation Facility at CERN (GIF)~\cite{mdt_highrates}. While the
$\gamma$-rates at the GIF correspond to only about 30 \% of the background levels expected for the
hottest regions at the SLHC, the results of these measurements already allow to define the baseline
of a chamber design with much improved tracking capability: MDT drift tubes with only half the tube
diameter offer a reduction of the drift time by a factor 3.5, due to the non-linear relation
between track distance from the central wire and drift time (r-t relation) and in addition by a
factor 2 from the exposed area, thus yielding a factor 7 in the reduction of the hit rate due to
n/$\gamma$ background. Moreover, up to two times more tube layers can in principle be accommodated
in the available space, leading to improved track finding efficiency and position resolution (see
Fig.~1).

The reduction of the tube diameter of the MDT tubes allows to maintain the main advantages of the
drift tube concept:
(a) independence of the position resolution from the angle of incidence onto the chamber plane
(contrary to drift chambers with rectangular drift geometry)
(b) operational independance of each tube, where any malfunction of a tube can only generate a
negligible inefficiency 
(c) modularity of chamber construction.

To verify the performance of 15 mm (''small'') tubes a number of tests was executed, using cosmic
muon tracks. A pair of 30 mm (''large'') drift tube chambers was used as reference,  defining the
position of the muon track,  while a layer of small tubes was the device under test.  Tubes along
the track are called 'efficient' when the hit is detected inside a 3$\sigma$ road, as defined by
the reference tubes. 

% --- Fig.  3 -------------------------------------------------------------------------------
\begin{figure}[ht] 
\begin{center}
\includegraphics[width=0.7\linewidth,clip]{Figures/Sm_tbs_design}
\label{Small_tube_structure} 
% 
%
\caption{Structure of a small drift tube with gas connection 
and decoupling capacitor in the longitudinal
direction (green cylinder). The plastic parts are injection moulded.}
% 
\end{center}
\end{figure}
% ----------------------------------------------------------------------------

This measurement was done in the presence of adjustable levels of gamma background  due to the GIF
facility at CERN~\cite{mdt_slhc}. Fig.~\ref{Large_small_efficiency} shows the efficiency of small
and large tubes vs. hit rate from gamma conversions. As expected, small tubes  provide a much
better performance at high background rates.  The efficiency at rate zero deviates from 100 \% due
to tracks passing across or close to the tube walls and due to $\delta$-electrons shifting the hit
position outside the 3$\sigma$ acceptance road. The average position resolution in the small tubes
was about 120 $\mu$m.  Due to the short drift compared to large tubes,  this value showed little
dependence on the background rate.

% ========================================================================================
\subsubsection{Technical Implementation}
% ========================================================================================
%

Going from large to small tubes as construction elements for MDT chambers poses a 
number of technical challenges, as the higher tube density requires more refined 
electrical and gas connections on the same available service area. 

% --- Fig.  4 ----------------------------------------------------------------
\begin{figure}[h]
\begin{center}
\includegraphics[width=0.9\linewidth,clip]{Figures/Sm_tbs_chamber_glueing}
\label{Sm_tbs_chamber_glueing}
%
\caption
{The small tube prototype chamber after assembly,
consisting of two modules of 8 tube layers, 72 tubes per layer and
1152 tubes in total.}
%
\end{center}
\end{figure}
% ----------------------------------------------------------------------------

A particular problem is the supply of the tubes with the operating voltage of 2730 V, 
requiring isolation distances which cannot be realized on the area available for the 
readout boards. The integration of the HV decoupling capacitors into the end-plugs of 
the tubes was therefore a central requirement for the tubes. In a similar way, gas 
supplies had to be simplified to facilitate the integration of the tubes. Fig.~3 shows 
the tube design, HV capacitor and gas distribution being integrated into the structure 
of the end-plug.

The integration of tubes into chambers is achieved by bonding tubes layer by layer 
with epoxy glue. In production tests, tubes were fixed in precision supports 
(''combs'') during curing, and the target accuracy of 20 $\mu$m was obtained. A module 
with 8 tube layers was glued in a time span of a few hours. With curing overnight, the 
assembly of a module took only one day.

Presently, a full prototype of a MDT chamber in small tube technology is under 
construction. It consists of 2$\times$8 tube layers and is designed to fit into the 
inner part of the muon detector in the very forward direction, where rates are highest 
(Fig. 4). This prototype will be available for tests in a muon beam at CERN and in the 
GIF facility in summer 2010. The readout will be achieved with available electronics 
for the large tube chambers, specially adapted for use with the new chamber geometry. 



%%% Sample tables commented out on 22.07.11 RR

\if{0}

Now comes a first example of a table 

  \begin{table}
    \centering
    \begin{tabular}{lrr}
      Micromega/TGC/RPC/MDT & Type 1 & Type 2\\
      \hline
      Number of chambers & & \\
      Radial extension (mm)& & \\
      Minimum length in $\phi$ (mm)& & \\
      Maximum length in $\phi$ (mm)& & \\
      Thickness in z (mm)& & \\
      Mass (kg) & & \\
      Number of layers & & \\
      Number of channels & & \\
      \hline
    \end{tabular}
    \caption{Example table chamber types}
    \label{tab:chamber_type}
  \end{table}

Now comes a second example of a table 

  \begin{table}
    \centering
    \begin{tabular}{lrr}
      Chamber & Small sector & Large sector\\
      \hline
              &  put in      &  a number! \\
      \hline
    \end{tabular}
    \caption{Example table: Number and types of chambers per sector}
    \label{tab:sector_type}
  \end{table}

\fi



\subsection{Performance}

{\it
  Summary of chamber performance, details in appendix of technology. 
  \begin{enumerate}
  \item Spatial and angular resolution as functions of rate and angle
    of incidence
  \item Time resolution
  \item Efficiency (single measurement and segment)
  \item Double track resolution
  \item Rejection of fake and background tracks
  \end{enumerate}
  
}

\subsection{L1 trigger and electronics}
\label{chapter:TGC}
{\it
  \begin{enumerate}
  \item How the L1 signal are produced, starting from the detector signal
    till the formation of SL input.
  \item Latency (calculation, measurement with demonstrator)
  \item Compatibility with Phase II upgrade   !!! RR to supply text !!! 
  \end{enumerate}

}


\subsection{Readout electronics and integration in DAQ}
\label{chapter:MDT_electronics}
{\it
  Detailed description of electronics chain.-- Integration to DAQ (Mention the GBT?).--
  Readout related parameters, e.g. bandwidth requirements, number and granularity of 
  read-out links.-- Compatibility with Phase II upgrade.
}

%%%%%   aaaa cccc nnnn xxxx yyyy zzzz

The readout of the Small MDT tubes follows the proven architecture of the
present MDT system, however, a number of modifications and additions is required
to improve the rate capability and to adapt the layout to the four times higher
channel density on the front faces of the Small tube chambers. 

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").

%%% figure 1
%
\begin{figure}[!htb]
%
\begin{center}
%
\includegraphics[width=0.50\linewidth,clip]{Figures/MDT_electronics_scheme_old}

\caption{Schematic diagram of the present MDT readout chain. 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, corresponding to 432 tubes, 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}
%

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. These data 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 DCS via CSM,
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}.

For an 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, a higher bandwidth of
the readout system has to be achieved. 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 from CSM
to ROD, the S-link protocol only supporting 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.

Apart from performance limitations, the presently used ASICs suffer from the fact that
their technologies do no longer exist. In order to replace obsolete technologies, the
following new components had therefore to be introduced into the new architecture.

\begin{itemize}
  \item The ASD is re-designed in the IBM 130 nm technology. A 4-channel prototype,
  demonstrating the analog parameters, has already been produced and works correctly.
  Most analog parameters of the previous design are preserved.
   
  \item The TDC will be replaced by the HPTDC, designed by the CERN-MIC group
  (~\cite{The_HPTDC}). This is a 32-channel device with improved internal buffering and
  higher tranfer and processing rates.
  
  \item The link connecting the CSM to the ROD will be replaced by a GBT link,
  developed by CERN. This link provides a 3 times higher transfer rate (Gbit/s),
  compared to the S-link. 
  \end{itemize}


\begin{figure}[!htb] 

\begin{center}

\includegraphics[width=0.85\linewidth,clip]{Figures/print_summary_LARGE_FF}

\caption{
Efficiency (left) and saturation of the readout link between TDC and CSM in edge mode
(right) as a function of the tube hit rate for dead time 750 ns (blue) and 200 ns (red).
The dotted curves in the right diagram correspond to pair mode. The dotted horizontal
line marks the minimum efficiency required for reliable tracking (left) and the maximum
saturation level recommended for the readout. {\bf This numbers will be checked. The
diagrams will be simplified.}}

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

Another stringent requirement for the practical 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 on the chamber ends is four times higher than in the
case of the Large tubes. The following design changes were therefore necessary.

\begin{itemize}

  \item 
  HV decoupling capacitors are located in 15 mm diameter cylinders at the tube ends, see
  Fig.~\ref{Small_tube_structure}. 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 The mezzanine card has to serve a four times higher channel density. We will
  change the ASDs into a 16-fold modularity and use the 32-channel HPTDC. To gain
  additional space, the passive protection circuitry of the ASD inputs will be
  moved to the hedgehog card. 
  
  \item 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.
  
  \item 
  While the power dissipation of the on-chamber frontend electronics of the present
  system was xx W/channel, leading to a dissipation of yy W/m in multilayers with 4 tube
  layers, the dissipation would now be about zz W/m. This may require flushing with dry
  air or even liquid cooling, as natural air convection is hampered by the tight space
  constraints of the Small Wheel.

\end{itemize}

Now something about mechanics, real estate, component density, packaging etc.

Finally something about rates.


\subsection{Services, infrastructure, and DCS  !!! RR+JD to supply text !!!}

{\it
  \begin{enumerate}
  \item Description of service scheme (including power system,
    read-out, trigger, alignment), cooling needs and other special
    requirements
  \item Table with number of services (number of cables, outer
    diameter, cross section of leads)
  \item Table with power consumption (per channel, chamber, total)
  \item Required rack space 
    \begin{enumerate}
    \item UX15 (include maximum allowed distance to detector if any) 
    \item US15 (power system)
    \item USA15 (DAQ)
    \end{enumerate}
  \item Gas system and distribution\\
    Details on number of gas manifolds per sector (include drawings)
    and connections to chambers (serial, parallel?)). Size of pipes\\
    Required nominal, minimum, and maximum flow\\
    Required precision of gas mixture\\
    Safety measures in case of inflammable gas\\
    Required rack space for gas system in SGX1, USA15, UX15
  \item Integration in DCS system, requirements for DCS !!!  Via GBT or ELMB++ ?? !!!
  \end{enumerate}

  \begin{table}
    \centering
    \begin{tabular}{lccc}
      Cable & Number of cables & Outer cable & Cross section\\
      & (granularity) & diam. (mm) & of leads (mm$^{2}$))\\
      \hline
      HV & & & \\
      LV & & & \\
      Monitoring and control & & & \\
      Front-end links & & & \\
      Calibration & & & \\
      Alignment & & & \\
      Miscellaneous & & & \\
      \hline
    \end{tabular}
    \caption{Example table number of services per chamber}
    \label{tab:services}
  \end{table}


  \begin{table}
    \centering
    \begin{tabular}{lccc}
      Chamber & Number of channels & Power consumption per channel &
      Total power consumption\\
      \hline
      & & & \\
      \hline
    \end{tabular}
    \caption{Example table: Number and types of chambers per sector}
    \label{tab:sector_type}
  \end{table}

}

