preliminary report for front-end electronics

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+\documentclass{JACoW-GSI-2013}
+\usepackage{graphicx}
+\usepackage{url}
+\usepackage[utf8]{inputenc}
+\usepackage{amsmath}
+\usepackage{amssymb}
+%% GSI Scientific Report 2013 
+%% \setlength{\titleblockheight}{27mm} KG
+\setlength{\titleblockheight}{35mm}
+
+\begin{document}
+\title{The CBM MVD read-out electronics\thanks{Work supported by
+BMBF (05P12RFFC7), HIC for FAIR and GSI}}
+
+\author[1]{J. Michel}
+\author[1]{M. Wiebusch}
+\author[]{the CBM-MVD collaboration}
+\affil[1]{Goethe-Universität Frankfurt}
+
+\maketitle
+\section{electronics}
+The CBM Micro-Vertex-Detector (MVD) front-end electronics serve as an intermediating
+device between the Monoilithic Active Pixel Sensors (MAPS) and the DAQ system
+(based on the TRB3 system developed by HADES).
+In the current connection scheme, one TRB3 FPGA board can support up to 16 sensors of type "MIMOSA26"
+in parallel. 
+
+These custom-built PCBs are necessary to supply the sensors with electrical power
+and to convert between different digital signal standards. The central element of the
+front-end electronics is the converter board. In addition to remote controlled power supplies,
+signal switches and drivers, it features an ADC section to monitor the sensor’s momentary
+electrical parameters.
+
+The sensors have to be supplied with a sensitive external biasing voltage, the so-called clamping voltage,
+which gets distributed to all sensor pixels.
+Several generation and distribution schemes were implemented to 
+investigate which setup results in the best noise performance.
+
+\section{measurements}
+The MIMOSA26 provides a test mode to measure the discriminator transfer function\footnote{The firing
+probability of a binary pixel as a function of discriminator threshold; usually has the form
+of a sigmoid function.} of all pixels. The slope steepness is directly related to the temporal
+noise of the detector.
+
+The read-out FPGA desgin was extended to operate and read out the sensor in this test mode.
+The recorded data yields valuable information about the noise performance of the detector
+hardware. To evaluate these data a dedicated analysis software was written.
+Noise tests with MIMOSA26 are ongoing. However, preliminary results concerning the influence
+of the clamping voltage suggest that it is beneficial to generate this reference voltage as
+close to the sensor as possible and to use decoupling capacitors, if possible, next to the
+bonding pads on the flex print cable.
+
+Furthermore the ADC section on the converter board can be used to perform systematic scans
+in order to characterize the sensors. As an example of such an automatic scan, Fig. \ref{current_digital}
+shows the dependence of the sensor's current consumption on the discriminator threshold setting.
+
+\begin{figure}[ht]
+\centering
+\includegraphics*[width=70mm]{current_digital.png}
+\caption{The current consumption (digital VCC) of a MIMOSA26 sensor as a function of the discriminator threshold.
+Data were acquired with monitoring devices integrated into the front-end electronics.}
+\label{current_digital}
+\end{figure}
+
+% \section{software development}
+% In order to operate the MVD test setup, the MVD user software handles the
+% coordination of data taking and continuous monitoring of sensor parameters (power consumption,
+% temperature, etc). Furthermore it allows for convenient editing of sensor and electronics settings.
+
+\section{laboratory instrumentation}
+When characterizing MAPS sensors, it is desirable to investigate the temperature dependence of certain
+sensor parameters. Until recently such tests could only be done using a large cooling system which
+circulates silicone oil through a cooling block to which the sensors under test are attached.
+This set-up was greatly reduced in size, while at the same time improved in usability.
+The sensors are now operated on a small copper platform which is cooled with a peltier element. A PID
+controller implemented on a microcontroller senses the temperature of the platform by means of a onewire temperature
+sensor and regulates the current through the peltier element. The device features a small display and a
+simple user interface, alternatively it can be remote controlled via a USB connection.
+
+\section{Presto}
+Current activities focus on bulding a demonstration version\cite{presto} of a quadrant of one of the rear stations of the MVD.
+For now, MIMOSA26 MAPS are used in this project though they do not qualify to be used in the final detector.
+Parts of the front-end electronics are currently redesigned to fit the spacial constraints of the set-up.
+
+
+\begin{thebibliography}{9} 
+
+\bibitem{presto}
+Tobias/Michal - something on Presto, this issue.
+
+
+\end{thebibliography}
+
+\end{document}
+