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-The MVD simulation model is subject to a major revision.
-Although this process is not fully completed, considerable progress has been achieved.
-In the following its motivation and progress are discussed.
+The MVD simulation model is subject to a major revision and considerable progress has been achieved.
+In the following its motivation and status are discussed.
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+\vspace{-3.mm}
\section{Motivation}
-Due to its proximity to the target and its excellent spatial resolution the MVD is the dedicated detector to resolve secundary vertices and to assist in the di-electron background suppression.
-However, the primal implementation lacked in a realistic description (with respect to e.g. the material budget or peculiar sensor features) for advanced studies.
+Due to its proximity to the target and its excellent spatial resolution the MVD is the dedicated detector to resolve secondary vertices.
+In addition, its capability to clean-up background in di-electron spectra is subject of a dedicated study [1].
+However, the primal implementation in simulation lacked in a realistic description (with respect to e.g. the material budget or peculiar sensor features) for advanced studies.
These studies are needed to develop strategies to achieve best performances, to analyze critical points and to finalize the concept of the MVD and its tools.
-The revision of the MVD model, to be incorporated to the CbmRoot simulation framework, attends to this and aims at a more realistic description of the current understanding of the MVD. % of the MVD.
+The revision of the MVD model, to be incorporated to the CbmRoot simulation framework, aims at a more realistic description of the current understanding of the MVD.
Before, in the standard scenario, the MVD was simplified as two homogeneous discs at 5\,cm and 10\,cm downstream the target, with an outer (inner) radius of 2.5\,cm (0.5\,cm) and 5\,cm (0.5\,cm), respectively.
-As no representation of individual sensors was made, this simplification involved many limitations.
+As no representation of individual sensors was included, this simplification possesses many limitations.
+The limitations involves mainly sensor properties beyond the hit response as e.g. the data parallelism of sensors, the rolling-shutter frame read-out, bandwidth limitations, busy circuits, a definition of a fake hit rate, time stamping and the data format.
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-\section{Approach}
-The new approach addresses this issue.
-Based on the MIMOSIS sensor characteristics, a detailed geometry with four stations (at 5\,cm, 10\,cm, 15\,cm and 20\,cm downstream the target) including all relevant features was elaborated in CAD.
+The new approach [2] addresses these issues and is based on a segmented geometry with four stations (at 5\,cm, 10\,cm, 15\,cm and 20\,cm downstream the target) including all relevant features.
+Its underlying sensor characteristics are borrowed from MIMOSIS.
+The detailed geometry was elaborated in CAD.
The conversion from the respective description into the ROOT geometry format was conducted by a dedicated tool.
In this way we are able to respond very quickly to changes in the detector design.
-Along with the proper representation of the gradual material budget, a new possibility of data processing is provided, as hits can be assigned to sensors now.
-In this process the data processing chain was adapted, the digitizer, clusterfinder and hitfinder working on sensor level.
-For each data processing step Monte Carlo hits, firing pixels or clusters of firing pixels are passed to the respective sensor station by station.
-
-In this regard firing pixels are particularly important, as they describe the response of the sensor to impinging hits mimicked by the digitizer.
-Apart from the generated signal of single hits the interference among hits is important to consider.
+Along with the proper representation of the gradual material budget, there is the possibility to incorporate the missing features mentioned above, as hits are assigned to sensors now.
+The data parallelism is incorporated by restructuring the data processing through the three process steps called digitizer, clusterfinder and hitfinder.
+Here, the corresponding data representations called Monte Carlo (MC) hits, digis (firing pixels) and clusters, which serve as input for the respective process step are assigned to the respective sensors.
+All further properties of the sensors are incorporated within the digitizer.
+%In this process the data processing chain was adapted, the digitizer, clusterfinder and hitfinder working on sensor level.
+%For each data processing step MC hits, digis or clusters are passed to the respective sensor.
+%A station comprises the totality of all respective sensors.
+As previously mentioned digis are particularly important, as they describe the response of the sensor to impinging hits mimicked by the digitizer.
+Apart from the generated pattern of single hits the interference among hits is important to consider.
+This is implemented in the digitizer by creating the signal amplitudes and distributions of all hits before jointly discriminating to generate the binary charge measurement.
Hits from consecutive events might pile-up and/or neighboring hits merge.
-This is particularly true due the long integration time of one frame.
-These features require the representation of the sensors rolling shutter frame read-out and a definition of the temporal sequence of the recorded hits accordingly.
-This allows moreover to represent further properties as busy circuits\footnote{Due to the given read-out time of one frame, the processing and output time of firing pixels in the on-chip zero suppression logic is constrained. This is limiting the bandwidth and hence possible pixel multiplicities in one frame.} and time stamping of hits in its native way.
-These considerations correspond to the time-based (4d) reconstruction and poses a challenge to the tracking telling the events apart.
-
-In oder to verify the perfomance in the reconstruction (e.g. tracking) matching of all data states is incorporated.
+This is particularly true due the long integration time of one frame of $\sim30\ \mu s$.
+The respective output is dependent upon the features included as listed above.
+These features require a definition of the temporal sequence of the recorded MC hits accordingly.
+Its considerations are relevant especially for the time-based track reconstruction of CBM. % in combination with the rather long integration time per frame.
+%correspond to the time-based (4d) reconstruction and poses a challenge to the tracking telling the events apart.
The time-based consideration is a necessary condition to use the reconstruction software with real data, too.
-Here the sensor parallel data processing discussed above provides a useful approach to speed up time critical processes as cluster- and hitfinding.
+%Here the sensor parallel data processing discussed above provides a useful approach to speed up time critical processes as cluster- and hitfinding.
-All geometry information are accessible via the 'geo\-handler'.
-For the tracking a simplified representation of the material budget is provided in the form of a map.
+In order to verify the performance in the reconstruction (e.g. tracking) matching of all data states is incorporated.
+All geometry information are accessible via the 'Geo\-Handler'-Class.
+For the tracking a simplified representation of the material budget is provided in the form of a map in dedicated files provided together with the digitizer.
In order to study the impact of misalignment the position of the individual sensors can be modified within simulation.
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+\vspace{-3.mm}
\section{Status}
-The new MVD geometry and data processing has been incorporated and submitted to CbmRoot.
+The new MVD geometry and data processing has been incorporated and uploaded to CbmRoot.
All functionality has been re-established and can be used within the event-based reconstruction.
Due to constraints on the part of CbmRoot, the time-based reconstruction is not fully available for the time being.
Likewise the MVD model does not yet comprise all the details.
-However, all preparations necessary has completed.
-The pile-up of events can be studied via background events
-Moreover, further details related to the performance of the sensor (as e.g. altering with the integrated radiation dose, noisy pixels, different pixel geometries) have not yet been treated.
+However, all preparations necessary have been provided.
+The pile-up of events can be studied via background events.
+Moreover, further details related to the performance of the sensor (as e.g. aging with the integrated radiation dose, noisy pixels, different pixel geometries) have not yet been treated.
+
+The current representation of the MVD in simulation is the prerequisite to allow for realistic simulations on the performance of the MVD in secondary vertexing and background rejection in di-electorn spectroscopy.
-The current implementation of the simulation is supposed to be in a very good condition to generate robust results needed for the TDR.
%\section{Results}
%\section{Summary}
-
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\begin{thebibliography}{1} % Use for 1-9 references
%\begin{thebibliography}{99} % Use for 10-99 references
-\bibitem{}
-Philipp Sitzmann, "Integration eines sensorbasierten Detektorresponsemodells", Master-thesis 2015
+\bibitem{} Erik Krebs, "Background rejection in the dilepton analysis with the CBM-Micro Vertex Detector", this report
+\bibitem{} Philipp Sitzmann, "Integration eines sensorbasierten Detektorresponsemodells", Master-thesis 2015
jspc29 / reports.git / commitdiff