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The Status of the Data Analysis of
the Beam Test at FZJ
March, 8th 2010 | T. Randriamalala, J. Ritman, T. Stockmanns and H. Xu
Outline
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Introduction
Raw Data Structure
Data Analysis Chain in PandaRoot
Data Analysis
Detector Alignment
Conclusion
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Introduction
 Proton beam test of the Bonn silicon tracking station has been
performed at Cosy at FZJ on February 2nd , 4th and 5th 2010.
 Different geometries and 2 beam momenta (2.95 GeV/c and 0.893
GeV/c) were used (cf Huagen Presentation)
 The whole frame and the software interface have been designed
and built by the Bonn Group.
 Goals:
o Mvd development,
o LM digitization process test.
 Participants:
o Mvd Bonn Group,
o LM Jülich Group.
 Data analysis is being performed within PandaRoot fromework.
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4 Single-Sided Silicon Strip Sensors
Scintillator fiber trigger
sytem
2 Double-Sided Silicon Strip Sensors
Picture of the BonnTracking Station
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Raw Data Structure
 Event trigger :
3 coincidence hits of the
4 scintillating fibers
 24 APV front-end
(labelled from 0 to 23)
 128 channels per frontend (labelled from 0 to
127)
 Sensor thickness : 300mm
 Pitch : 50 mm
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Data Analysis Structure
Geometry &
Digi Parameters
Data & Calibration
Files
PndMvdCreateDefaultApvMap
Geometry Map
PndLumiConvertApv
Digitization Hits
PndLumiClusterTask
Reconstructed Hits
PndLumiTrackFinder
Track Candidates
PndDmlLinFitTask
Reconstrcuted Tracks
ref: https://subversion.gsi.de/trac/fairroot/browser/pandaroot
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Data Analysis (1)
 Data analysis of the first day run:
o Beam momentum : 2.95 GeV/c
o z-positions :
Box1: 110mm, Box2: 807mm,
Box3: 1390mm, Box4: 1832mm.
o x-position shift from the beam axis:
Box1: -6mm, Box2: 4mm,
Box3: -1mm, Box4: 1mm.
o Average noise: 500 electrons
o Threshold:
FE 0-17: 3000 electrons (first 6 sensors)
FE 18-23: 6000 electrons (last sensor)
 Confrontation with MC simulation is carried out along the analysis.
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Data Analysis (2)
 Sample data : 34632 events
 Digis multiplicity per event
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Data Analysis (3)
 Strip fired at the first plane:
This shows the beam particle distribution on x and y coodrinates:
o mx =-0.343cm, sx=0.64cm
o my =-0.01cm, sy=0.3cm
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 For MC simulation, the beam smearing was applied for primary
particles with the obtained values.
 After the digitization process, the strip fired distribution at the
first plane:
The angular divergence needs to be calculated !
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Clusterization
 The cluster size:
o ~40% cluster size > 1
o ~27% cluster size >1
 Difference is due to the non-implementation of the angular divergence
for the MC simulation : MC Tracks are normal to the detcctor surface
 Charge Calibration :
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~40 keV
~ 90 keV
Factor of 2.25 of difference
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Strip ID
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Tracking (1)
 The track finder consists in collecting hits which are close to each
other in xy plane within an area of dr of radius.
 With the same search radius:
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Tracking(2)
 However, the number of reconstructed hit per event per plane
 Most of the case: multiplicty 1 (1 track per event)
 Reconstruted hits are far from each other for the data.
Misalignment of the sensors!
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Alignment
 Detector alignment proposition (on x and y):
o Focus on 1 hit multiplicity per plane
o Fit the first two hits on one
line and the last two on
another line (step 1)
Middle plane
o Calculate the difference on x,
y, q and j of the intersection
points of the two with a virtual
middle plane (step 2)
dx,y,q,j
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Result:
Unlike the MC simulation,
the 2 lines from data have
not the same direction.
Goal : reduce dx,y < 7mm (hit
resolution)
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o Fit the 4 hits and calculate the difference between the hit position
and the fit line position at each plane (step 3).
Data
Simulation
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o Shift the detector on x and y by the means of those distributions
(step 4)
o ( Output of steps 1 & 2)
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o Redo step 3
o Redo step 4
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sx,y~6mm
The 2
lines
become
colinear
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Result
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Initial Position (cm)
Final Position (cm)
Box1
(-0.600, 0.000, 11.000)
(-0.274, 0.072, 11.000)
Box2
( 0.400, 0.000, 80.700)
(-0.292, -0.082, 80.700)
Box3
(-0.100, 0.000, 13.900)
(-0.038, -0.090, 13.900)
Box4
( 0.100, 0.000, 18.320)
( 0.069, 0.102, 18.320)
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Conclusion
 We had a successfully data acquisition for the Bonn tracking system
beam test.
 Data analysis is ongoing.
 A proposition of detector alignment on xy plane has been described..
 A confrontation of the data with .the MC simulation has been shown.
 The beam divergence needs to be determined for further studies.
To be continued …
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Thank you!
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 Multiply charge at every
strip by 2.25
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Peak at
80 keV
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