\author[1]{M. Koziel}
\author[1]{B. Milanovic}
\author[1]{S. Amar-Youcef}
+\author[1]{P. Klaus}
\author[1,2]{J. Stroth}
\author[ ]{the CBM-MVD collaboration}
\affil[1]{Goethe-Universität Frankfurt}
The CBM Micro-Vertex-Detector (MVD) front-end electronics serve as an intermediating
device between the Monolithic 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 the current connection scheme, one TRB3 FPGA board can support up to 16 sensors of type "MIMOSA-26"
in parallel.
-
The front-end electronics are necessary to supply the sensors with electrical power
and to convert between different digital signal standards. The central element of these custom-built
PCBs 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
+The MIMOSA-26 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
+noise of the sensor.
+The read-out sytem was extended to operate and read out the sensor in this test mode.
+The recorded data is evaluated by a dedicated ROOT-based analysis software.
+% 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 MIMOSA-26 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]{BankB_CurrentDigital.eps}
-\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.}
+\caption{The current consumption (digital VCC) of a MIMOSA-26 sensor as a function of the discriminator threshold.
+Data acquired with front-end electronics on-board monitoring devices.}
\label{current_digital}
\end{figure}
\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
+sensor parameters. Until recently, such tests were conducted 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
+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.
+The platform can be cooled down to circa $-10^{\circ}\rm{C}$ within few minutes while consuming $50\,\rm{W}$.
+Overall, the set-up was greatly reduced in size, while at the same time improved in usability.
\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.
+Current activities focus on bulding a demonstration version\cite{presto} of a quadrant of the second station of the MVD.
+For now, MIMOSA-26 sensors 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}
-Michal Koziel, Tobias Tischler et al.,PRESTO: PREcursor of the Second sTatiOn of the CBM-MVD, this issue.
+M. Koziel, T. Tischler et al.,PRESTO: PREcursor of the Second sTatiOn of the CBM-MVD, this issue.
\end{thebibliography}
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