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Analog vs. DigitalAnalog vs. DigitalHadronHadron CalorimetryCalorimetry
for the ILCfor the ILCDhiman Chakraborty
for the NIU/NICADD ILC detector group
International Linear ColliderLarge Detector Meeting
LLR, Paris, January 13-15, 2005
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 2
IntroductionIntroduction
We consider a hadronic calorimeter with a few thresholds (1-3).Compare gas and scintillator as live media:
Single particle energy resolution,Shower width,Clustering.
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 3
Geometries ConsideredGeometries Considered
Scint HCal
Steel 20mmPolystyrene 5mm
Gas Geom1
Steel 20mm
Gas 5mm
Gas Geom2
G10
Glass 1mm
Gas 1mm
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 4
Number of cells hit by Number of cells hit by ππ++s of s of 2, 5, 10, 20, 30, 50 GeV2, 5, 10, 20, 30, 50 GeV
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 5
ππ++ energy resolution as function of energy resolution as function of energy for different (linear) cell sizesenergy for different (linear) cell sizes
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 6
EEnergy resolution for 10 GeV nergy resolution for 10 GeV ππ++ss
σ/E=0.183 σ/N=0.166
9cm2 cells
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 7
EEnergy resolution for 50 GeV nergy resolution for 50 GeV ππ++ss
σ/E=0.101 σ/N=0.153
9cm2 cells
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 8
Nhit Nhit correlations for different correlations for different cell energy thresholdscell energy thresholds
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 9
Nhit correlations for different cell Nhit correlations for different cell energy thresholdsenergy thresholds
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 10
Nhit correlations for different cell Nhit correlations for different cell energy thresholdsenergy thresholds
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 11
Alternatively,Alternatively,
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Analog vs. Digital HCal for ILC Dhiman Chakraborty 12
CompensationCompensation
Cell counting has its own version of the compensation problem (in scintillators).With multiple threshold this can be overcome by weighting cells differently (according to the threshold they passed).In MC, 3 thresholds seem to be adequate
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 13
After semiAfter semi--digital treatmentdigital treatment
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 14
Energy resolution:Energy resolution: 5050 GeV GeV ππ++ss
σ/E=0.101 σ/E=0.092
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 15
Energy resolution: 10 GeV Energy resolution: 10 GeV ππ++ss
σ/E=0.183 σ/N=0.164
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 16
ππ++ energy resolution vs. energyenergy resolution vs. energy
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 17
Time of flightTime of flight
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Analog vs. Digital HCal for ILC Dhiman Chakraborty 18
ToF dependenceToF dependence
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Analog vs. Digital HCal for ILC Dhiman Chakraborty 19
CrossCross--talktalk(10% of cell E leaks equally to 4 neighbors)
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 20
Nhit vs. fraction of Nhit vs. fraction of ππ++ E in cells with E>10 MIP:E in cells with E>10 MIP:1cm1cm x 1cm x 1cm scintillator cellsscintillator cells
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 21
Nhit vs. fraction of Nhit vs. fraction of ππ++ E in cells with E>10 MIP:E in cells with E>10 MIP:GasGas vs. scintillatorvs. scintillator
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 22
ππ++ energy resolution vs. energyenergy resolution vs. energyM
ultip
le th
resh
olds
not
use
d
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 23
NonNon--linearitylinearityNhit/GeV varies with energy.This will introduce additional pressure on the “constant” term.For scintillator the non-linearity can be effectively removed by “semi-digital” treatment.
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 24
Density of hitsDensity of hits
Need a hierarchy in the absence of an energy measurementLocal density of hits is an obvious candidate. A simple-minded density variable:
di = Σ (1/Rij),where Rij is the angular distance between cells i & j.
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 25
Position resolutionPosition resolutionM
easu
red
rela
tive
to th
e en
ergy
wei
ghte
d re
solu
tions
unweighted
Density weightedEnergy weighted
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 26
Density vs. Density vs. EnergyEnergy
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 27
WidthWidthFind centroid {Σwixi/Σwi}‘width’ = sqrt(ΣwiR2
i/Σwi)Three weights were used:
Unweighted (wi=1)
Energy weighted (wi=Ei)
Density weighted (wi=nearest-neighbor occupancy in a 5x5 window in lyrs k-1,k,k+1)
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 28
Distance to Distance to farthestfarthest cellcell
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Analog vs. Digital HCal for ILC Dhiman Chakraborty 29
Density Density of farthestof farthest cellcell
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Analog vs. Digital HCal for ILC Dhiman Chakraborty 30
Distance to farthest cellDistance to farthest cell
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Density of farthest cellDensity of farthest cell
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BackscatterBackscatter
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Shower Shower widthwidth for 10GeVfor 10GeV ππ±±
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Shower width for 50GeVShower width for 50GeV ππ±±
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π± angular widthrms shown as bars
ILC LD meeting, 14-01-2005
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ππ±± angular width: energy weightedangular width: energy weighted
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ππ±± angular width: density weightedangular width: density weighted
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CommentsCommentsThere is no clear cut case either way at the moment; detailed studies of assessing impact needed.Will look at cluster separability next.Need to evaluate this in the global context of calorimeter performance.
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Analog vs. Digital HCal for ILC Dhiman Chakraborty 39
ClusteringClusteringClustering based on local densityworks well.It is an alternative to track-seeded clustering.Can be used in the ECal and HCal.Full PFlow implementation givesencouraging results.
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 40
10 GeV10 GeV ππ0 0 →→ γγγγD
ensi
ty w
eigh
ted
θ−φ
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 41
ΣΣ++ →→ ppππ0 0 →→ ppγγγγ
p
π0
Den
sity
wei
ghte
dθ−
φ
ILC LD meeting, 14-01-2005
Analog vs. Digital HCal for ILC Dhiman Chakraborty 42
SummarySummaryLarge parameter space in the nbit-segmentation-medium plane for hadron calorimetry. Optimization through cost-benefit analysis?Scintillator and Gas-based ‘digital’ HCalsbehave differently.Need to simulate detector effects (noise, x-talk, non-linearities, etc.)Need verification in test-beam data.More studies underway.