Updates from Paul Colas

Author: jstrube

Spinoffs/Spinoffs.tex

@@ -163,7 +163,7 @@ \section{AIDA-2020 for LC experiments}
 
 AIDA-2020 follows the successes of the previous initiatives EUDET and AIDA. The infrastructure theme, although interpreted in a wider sense, moves common interests of R\&D groups into focus and helps structuring the activities. It builds on the achievements of EUDET and AIDA, e.g. test beam infrastructures like the TPC magnet, the pixel telescopes or software frameworks like DD4HEP, but it goes beyond in many respects. There is a three times larger budget to directly support users of, e.g., test beams, and there are new topics, like novel silicon sensors and micro-channel cooling.
 
-Efforts, with strong representation of LC groups, will enhance infrastructures to advance towards the construction phase of calorimeters and gaseous detectors. This includes test stands for the characterization of silicon sensors or optical read-out units for highly granular calorimeters, as well as installations for the production and characterization of large area gas detectors, RPCs, GEMs, and micromegas,. Test beam infrastructure is further improved, to keep pace with increased demands of precision detectors, e.g. by adding a silicon strip telescope for the \DIITBF.
+Efforts, with strong representation of LC groups, will enhance infrastructures to advance towards the construction phase of calorimeters and gaseous detectors. This includes test stands for the characterization of silicon sensors or optical read-out units for highly granular calorimeters, as well as installations for the production and characterization of large area gas detectors, RPCs, GEMs, and micromegas. Test beam infrastructure is further improved, to keep pace with increased demands of precision detectors, e.g. by adding a silicon strip telescope to the TPC test stand at the DESY.
 
 Development of micro-electronic ASICs directly supports the efforts in vertex detector, tracking and calorimeter R\&D. Particular attention, and a special fund, is devoted to the cooperation with industry and the transfer of technologies, e.g. for the production of large areas of silicon devices. Work on advanced software is strongly driven by LC needs and includes work on tracking tools and particle flow algorithms (PandoraPFA). The LC community had assigned high priority, in the proposal preparation phase, to the creation of a common DAQ framework for test beam experiments of several linear collider sub-detector prototypes in a combined set-up, which is now being pursued in a dedicated work package.
 

Tracker/TPC_Bonn/gating.tex

@@ -22,13 +22,11 @@ \subsection{Introduction}
 indicated by the red lines.
 
 \begin{figure}
-\begin{center}
+\centering
 \includegraphics[width=.7\textwidth]{Tracker/TPC_Bonn/plots/TPC-Gate_Fig1gating.pdf}%
 \caption{\label{Fig1gating} {Displacement due to the positive-ion discs.}}
-\end{center}
 \end{figure}
 
-
 In  Fig.~\ref{Fig1gating} it is assumed that for every drift electron one positive ion drifts back.
 The actual amount of displacement should therefore be multiplied by the ratio of the gas amplification
 factor to the suppression factor of the ion backflow of the MPGD system. Since the suppression factor by the

Tracker/TPC_Bonn/micromegas.tex

@@ -1,13 +1,13 @@
 \section{Resistive Micromegas}
 \label{chap:TPC_sec:micromegas}
-Most recent update: 2020-05-24\\
+Most recent update: 2020-07-24\\
 Contact person: Paul Colas (email: paul.colas@cea.fr)\\
 
 \subsection{Introduction}
 First Micromegas prototypes were built with a micro-mesh stretched on a frame, and kept on top of
-a segmented anode at a fixed distance of \SI{50}{\micro\meter}. The gap is defined by spacers manufactured
+a segmented anode at a fixed distance of \SI{50}{\micro \meter}. The gap is defined by spacers manufactured
 by photo-lithographic techniques. Early tests confirmed that, due to ``hodoscope effect'' a resolution
-down to \SI{100}{\micro\meter} could not be reached \cite{Arogancia:2007pt}. This triggered studies with charge spreading
+down to \SI{100}{\micro \meter} could not be reached \cite{Arogancia:2007pt}. This triggered studies with charge spreading
 developed at Carleton University~\cite{Dixit:2003qg}.
 The first resistive material was an AlSi CERMET deposited on a Mylar foil and glued at
 \SI{90}{\degreeCelsius} with layer of melting polymer~\cite{2007NIMPA.581..254D}. Later on, a more robust resistive material was
@@ -60,9 +60,33 @@ \subsection{Recent Milestones}
 
 In 2018, the endplate was equipped with 4 new modules with a DLC anode. Also, a new scheme was applied for the amplification High Voltage : the anode is set at a positive high voltage, and the Micromegas mesh is set to ground, as the surrounding supports. This allows a better field homogeneity near the module boundary and mitigates the distortions. In addition, this improved the operability of the detector : in case of breakdown of one module, its surface remains at ground, leaving the endplate equipotential. 
 
-\subsection{Engineering Challenges}
+The dE/dx resolution is shown in Fig.\ref{fig:fig440} as a function of track length. For the ILC TPC size, it is 5\%.
+\begin{figure}
+\centering
+\includegraphics[width=90mm]{Tracker/TPC_Bonn/plots/fig200116_dEdx_modCanvSize.eps}
+\caption{The dE/dx resolution as a function of the track length for \SI{5}{GeV} electrons. The red line is a power law.}
+\label{fig:fig440}
+\end{figure}
+The point resolution in the r$\phi$ and z coordinates are shown in Fig.\ref{fig:fig421}. The r$\phi$ resolution reaches \SI{65}{\micro\meter} at zero drift distance, and increases as expected with z, due to electron diffusion during the drift.
+
+\begin{figure}
+    \begin{minipage}{0.5\hsize}
+        \begin{center}
+        \includegraphics[width=76mm]{Tracker/TPC_Bonn/plots/fig200411_resoX_mod3_24Nov_B1_Ed230Vcm_Ed140Vcm}
+        \end{center}
+    \end{minipage}
+    \begin{minipage}{0.5\hsize}
+        \begin{center}
+        \includegraphics[width=76mm]{Tracker/TPC_Bonn/plots/fig200411_resoZ_mod3_24Nov_B1_Ed230Vcm_Ed140Vcm}
+        \end{center}
+    \end{minipage}
+\caption{The distributions of the spatial and z resolution as a function of the measured drift length, in black for a drift field of \SI{230}{\volt\per\centi\meter} and in blue for \SI{140}{\volt\per\centi\meter} (average over the 24 pad-rows of a module).}
+\label{fig:fig421}
+\end{figure}
+
 
-The requirements on the mechanical precision and flatness of the modules are very demanding to keep the systematics on the distortions below 10-20 microns.  
+\subsection{Engineering Challenges}
+The requirements on the mechanical precision and flatness of the modules are very demanding to keep the systematical errors on the sagitta from distortions below 10-20 microns.
 
 The adaptation of a gating device at a few cm from the end-plate, or integrated to each module, is a
 difficult engineering challenge if a minimal degradation of the performances is to be obtained.