From: Samir Amar-Youcef Date: Wed, 26 Feb 2014 12:15:19 +0000 (+0100) Subject: Korrekturen von MD X-Git-Url: https://jspc29.x-matter.uni-frankfurt.de/git/?a=commitdiff_plain;h=a2b1b020ec084c519e800468ccef66c5a05adc88;p=reports.git Korrekturen von MD --- diff --git a/GSI_2014_SA_BeamtimeResults/report.pdf b/GSI_2014_SA_BeamtimeResults/report.pdf index 784643f..9199f4f 100644 Binary files a/GSI_2014_SA_BeamtimeResults/report.pdf and b/GSI_2014_SA_BeamtimeResults/report.pdf differ diff --git a/GSI_2014_SA_BeamtimeResults/report.tex b/GSI_2014_SA_BeamtimeResults/report.tex index 171c78f..5aa28e4 100644 --- a/GSI_2014_SA_BeamtimeResults/report.tex +++ b/GSI_2014_SA_BeamtimeResults/report.tex @@ -21,48 +21,54 @@ %\section{Introduction} The prototype of the CBM Micro Vertex Detector (MVD) was commissioned and extensively tested at a beam time at CERN SPS. The performance of the sensors along with the customized frond-end and TRB based DAQ system was investigated -regarding the synchronization and long-term stability of the continuous multi-channel readout, the positional stability and the sensor performance (efficiency, resolution, fake hit rate). -As pixel sensors MIMOSA-26 \cite{MW} was used, which represents a sizable precursor to the final sensor. +regarding the synchronization and long-term stability of the continuous multi-channel readout, the positional stability and the sensor performance (efficiency, resolution, dark occupancy). +MIMOSA-26 \cite{MW}, which represents a sizable precursor to the final sensor of the MVD, was used. It comprises the prototype readout concept including on-chip hit discrimination and data sparsification. -Further, the sensor is based on a high-resistivity epitaxy layer and was thinned down to a thickness of 50\ $\mu$m. +Moreover, the sensor is based on a high-resistivity epitaxy layer and was thinned down to a thickness of 50\ $\mu$m. %\section{Setup} 12 identical sensors were arranged in four single-sided reference and one double-sided DUT station, whereas ``one side'' comprises two sensors side by side. -According to this the beam particles were tracked by up to 6 hit points. -Further, the setup allowed to vary the relative distance of the stations and the inclination of the DUT relative to the reference system. The DUT was sandwiched between two reference stations, respectively. -In addition the temperature of the DUT could be varied independent of the temperature of the reference system. -The material budget amounts to 0.05\%\ $X_{0}$ for each of the reference stations and 0.3\%\ $X_{0}$ for the DUT. -The DUT station corresponds to one fourth of a first MVD station. +According to this, the beam particles were tracked by up to 6 hit points. +The setup allowed to vary the relative distance of the stations and the inclination of the DUT relative to the reference system. +The temperature of the DUT could be varied independent of the temperature of the reference system. +The material budget amounted 0.05\%\ $X_{0}$ for each of the reference stations and 0.3\%\ $X_{0}$ for the DUT, which corresponds to one fourth of a first MVD station \cite{TT}. -The DAQ has worked reliably and has delivered 1.2\ TB of data. -Its most important analysis results are presented in the following. -Further information on the MVD can be found in \cite{BM, TT}. +Thanks to the reliable DAQ system \cite{BM}, 1.2\ TB of data were collected. +The most important results extracted from this data will be presented hereafter. %\section{Results} A diversity of measurements at different discriminating thresholds, inclination angles and temperatures were carried out. % to determine the performance of the MVD prototype. -The data was analyzed by an internal customized software. -The software performs data consistency checks, unpacking and high level analysis including QA functionalities and a dedicated alignment package, which was established according to its application to simultaneously align up to 6 sensors in the telescope setup. +The data was analyzed by means of a dedicated software. +The latter performs data consistency checks, unpacking and high level analysis including QA functionalities and includes an alignment package, which was designed to align the 6 sensors in the telescope setup. Figures \ref{fig:ShiftSpillTime} and \ref{fig:EffVsFakes} demonstrate the excellent performance of the MVD prototype. -Fig. \ref{fig:ShiftSpillTime} shows the temporal course of the alignment of the DUT relative to the reference system. -A change of $0.003\ \mu m/min$ could be resolved. -The single point resolution of the DUT including the resolution of the sensor and the positional stability of the mechanics was found to be about $3.6\ \mu m$. +Fig. \ref{fig:ShiftSpillTime} shows the position of the DUT relative to the reference system based on alignment results as a function of time. +A movement of $0.003\ \mu m/min$ was observed. +The single point resolution of the DUT including the resolution of the sensor and the positional stability of the mechanics was found to be about $3.5\ \mu m$. This is equivalent to the resolution of the sensor only, suggested by the pixel pitch of $20\ \mu m$, no charge decoding and an average cluster size between 1 and 2. -Fig. \ref{fig:EffVsFakes} shows the efficiency-fake hit relation of the two DUT sensors. +Fig. \ref{fig:EffVsFakes} shows the relation between the efficiency for MIPs of the two DUT-sensors and their dark occupancy. %For the experiment it is necessary to reduce the number of noisy pixels to a minimum at maximum efficiency in order to reduce the data throughput and ambiguities in the tracking. -The working points are given as a result from varying the on-chip discriminator thresholds. -For each working point a significant decrease of the fake rate with a slight loss of efficiency only can be obtained by masking noisy pixels. -This suggests that the majority of fake hits is caused by a subset of hot pixels only. +The data was taken varying the on-chip discriminator thresholds of the sensors. +We find that the ambitioned performance of $99\%$ efficiency and $10^{-5}$ dark occupancy are reached for both sensors. +Moreover, the dark occupancy can be reduced further by masking $<<1\%$ of noisy pixels. +This suggests that a large part of the dark occupancy is caused by a subset of hot pixels only. + +Over all we conclude that the prototype of the MVD reached the requirements of CBM in terms of mechanical stability and sensitivity for minimum ionizing particles. + + + +%For each working point a significant decrease of the fake rate with a slight loss of efficiency only can be obtained by masking noisy pixels. +%This suggests that the majority of fake hits is caused by a subset of hot pixels only. %In the figure the two approaches masking of noisy pixels and increasing the threshold are confronted. -In summary the sensors allow to operate at the desired operating point of above $99\%$ efficiency and below $10^{-5}$ hits per pixel and event fake rate. +%In summary the sensors allow to operate at the desired operating point of above $99\%$ efficiency and below $10^{-5}$ hits per pixel and event fake rate. \begin{figure}[h] \centering \includegraphics[width=0.335\textwidth]{ShiftSpillTime1.pdf} - \caption{Change of the translational relative alignment during one run. Each data point corresponds to one spill.} + \caption{Relative position of the DUT with respect to the reference telescope. Every point corresponds to one spill of the CERN-SPS.} \label{fig:ShiftSpillTime} \end{figure} @@ -88,10 +94,10 @@ In summary the sensors allow to operate at the desired operating point of above %\begin{thebibliography}{99} % Use for 10-99 references \bibitem{MW} J. Baudot, ``First test results of MIMOSA-26, a fast CMOS sensor with integrated zero suppression and digitized output'', IEEE Nucl. Sci. Symp. Conf. Rec.(2009) 1169. -\bibitem{BM} -B. Milanovic, ``Beamtime Results of the MVD Prototype DAQ Network'', GSI Scientific Report 2012 \bibitem{TT} T. Tischler, ``Layout of the Micro Vertex Detector for the CBM experiment'', this report +\bibitem{BM} +B. Milanovic, ``Beamtime Results of the MVD Prototype DAQ Network'', GSI Scientific Report 2012 \end{thebibliography}