the cbm sensor digitizer
DESCRIPTION
The CBM sensor digitizer. C.Dritsa IKF-Frankfurt, IPHC-Strasbourg (now at JLU Giessen). Outline. Motivation Model requirements Description of the model Important definitions (1) charge generation charge sharing Evaluation Important definitions (2) Comparison with experimental data - PowerPoint PPT PresentationTRANSCRIPT
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The CBM sensor digitizerThe CBM sensor digitizer
C.DritsaC.DritsaIKF-Frankfurt, IPHC-StrasbourgIKF-Frankfurt, IPHC-Strasbourg
(now at JLU Giessen)(now at JLU Giessen)
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OutlineOutlineMotivationMotivationModel requirementsModel requirementsDescription of the modelDescription of the model
Important definitions (1)Important definitions (1)charge generationcharge generationcharge sharingcharge sharing
EvaluationEvaluationImportant definitions (2)Important definitions (2)Comparison with experimental dataComparison with experimental data
OutlookOutlook
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MotivationMotivationDigitizer model developed in order to allow Digitizer model developed in order to allow simulating the CBM-MVD.simulating the CBM-MVD.
In collaboration with the In collaboration with the IPHC-PICSELIPHC-PICSEL group in Strasbourg and the group in Strasbourg and the IKF-MVDIKF-MVD group in Frankfurt.group in Frankfurt.
It was inspired by a detector response It was inspired by a detector response model developed for the ILC vertex tracker model developed for the ILC vertex tracker – M. Battaglia, “Response simulation of CMOS pixel sensors for M. Battaglia, “Response simulation of CMOS pixel sensors for
the ILC vertex tracker” , Nuclear Instruments and Methods in the ILC vertex tracker” , Nuclear Instruments and Methods in Physics Research A 572 (2007) 274–276Physics Research A 572 (2007) 274–276
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CBM-MVD response model requirementsCBM-MVD response model requirements
Realistic simulations allowing to simulate:Realistic simulations allowing to simulate:– Cluster properties: size, shape Cluster properties: size, shape – pixel sizepixel size– vary number of ADC channels of the readoutvary number of ADC channels of the readout– particles impinging with high incident anglesparticles impinging with high incident angles– noise, fake hitsnoise, fake hits
Rapid simulation featuresRapid simulation features– simulate collision pile upsimulate collision pile up– delta electrons (of concern in CBM) delta electrons (of concern in CBM) – fast, allowing high statistics simulationsfast, allowing high statistics simulations
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Spirit of the modelSpirit of the model
Challenge:Challenge:– Charge carrier transport process too complex Charge carrier transport process too complex
and slow for simulation and slow for simulation
Solution:Solution:– Parameterization of the sensor responseParameterization of the sensor response– Use experimental dataUse experimental data– GEANT provides only entry and exit GEANT provides only entry and exit
coordinates of the particle in the volumecoordinates of the particle in the volume– no dE/dx from GEANTno dE/dx from GEANT
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Reference dataReference dataData acquired at CERN/SPS with pions 120 GeV/cData acquired at CERN/SPS with pions 120 GeV/c
Sensor under test: MIMOSA17Sensor under test: MIMOSA17– AMS 0.35AMS 0.35– standard low resistivity epitaxial layerstandard low resistivity epitaxial layer– analogue output (12 bit charge resolution)analogue output (12 bit charge resolution)– 30 30 µµm pixel pitchm pixel pitch
Particle incident angles 0-75 degreesParticle incident angles 0-75 degrees(90 degrees is parallel to the sensor plane)(90 degrees is parallel to the sensor plane)
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The digitizerThe digitizer
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24
025
iiQQ
MP
V
Important definitions (1)Important definitions (1)
Landau
Lorentz
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Other featuresOther features
Simulated by random sampling of a Simulated by random sampling of a distribution following a Gauss law with distribution following a Gauss law with adjustable µ, adjustable µ, σσ
mean=0mean=0
σσ =15 electrons =15 electrons
Number of ADC bits adjustableNumber of ADC bits adjustable 12 bits12 bits
Pixel pitch adjustablePixel pitch adjustable 30 µm30 µm
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The model: InputThe model: InputThe charge of the cluster The charge of the cluster is taken by random is taken by random sampling of the sampling of the experimental distribution experimental distribution for 25 pixelsfor 25 pixels
0 degrees incident angle
The charge distribution The charge distribution among the pixels in the among the pixels in the cluster is based on a 2D cluster is based on a 2D Lorentz distribution Lorentz distribution (derived from the 1D)(derived from the 1D)
0 degrees incident angle
Landau:Accumulated charge on 25 pixels
The simulation of inclined particles is derived by this initial parameterization.
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The model: charge generationThe model: charge generation
QQ00, l, l00 : known : known
lincl: provided by : provided by GEANTGEANT0
0 l
lQQ incl
incl
inclincl lQ ,00 , lQ
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The model: charge distributionThe model: charge distribution
Charge provided by Landau (25 pixels)Charge provided by Landau (25 pixels)The trajectory is divided in segmentsThe trajectory is divided in segmentsA Lorentz function corresponds to each segmentA Lorentz function corresponds to each segment
Illustration for inclined track
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The modelThe model
L(xk,i,yk,i)
Charge on pixel i
Sum over segments (k)
x,y-coordinatesof pixel i Pixel pitch
LorentzAmplitude
Lorentzwidth
x,y-coordinatesof segment k
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EvaluationEvaluation
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Important definitions (2)Important definitions (2)
Number of PixelsAc
cum
ulat
ed c
harg
e (M
PV)
Q1 Q2
Q3
Q1>Q2>Q3…
Qi
Q1 Q2
Q3
Q1
Q1+Q2
Q1+Q2+Q3
Q1+Q2+…+Qi
Qi<0(i~N)
1 2 3 N…
The accumulated charge plot describes the charge sharing among the pixels of the cluster:
e.g. the seed pixel collects ~30% of the total cluster charge.
Accumulated charge plotAccumulated charge plot
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Evaluation: MPV of LandauEvaluation: MPV of Landau
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Evaluation: sigma of LandauEvaluation: sigma of Landau
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EvaluationEvaluation
Average number of pixels/clusterAverage number of pixels/cluster
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Evaluation: shapeEvaluation: shapeSimulation Experimental data
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Summary and outlookSummary and outlook
Digitizer model developed for the CBM-Digitizer model developed for the CBM-MVD and successfully tested with MVD and successfully tested with experimental data.experimental data.
Model was successfully tested on High-Model was successfully tested on High-Resistivity sensors (M.Domachowski)Resistivity sensors (M.Domachowski)
Successfully tested on neutron irradiated Successfully tested on neutron irradiated sensors (M.Domachowski)sensors (M.Domachowski)
Simulation of MIMOSA-26 data Simulation of MIMOSA-26 data sparcification in process (Q.Li)sparcification in process (Q.Li)
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AcknowledgmentsAcknowledgments
Thanks to:Thanks to:
the IPHC-PICSEL group and the IKF-MVD group.the IPHC-PICSEL group and the IKF-MVD group.
In particular:In particular:
IPHC:IPHC: J.Baudot, M.Goffe, R.DeMasi, M.Winter J.Baudot, M.Goffe, R.DeMasi, M.Winter
IKF:IKF: M.Deveaux, M.Domachowski, Q.Li, J.Stroth M.Deveaux, M.Domachowski, Q.Li, J.Stroth
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BackupBackup
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High-Res MAPS: Measurement vs. simulation
0 5 10 15 20 250
100
200
300
400
500
600
700
800
900A
ccum
ulat
ed c
harg
e [e
- ]
Number of pixels
Measurement Simulation
Simulation of irradiated MAPS in CBM-Root Melissa Domachowski - CBM Collaboration Meeting, Dresden 2011
Simulation of HR-MAPS with the MVD-digitiser: OKSimulation of irradiated MAPS: OK
Melissa Domachowski
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Particle yieldsParticle yields