EF with simple multi-particle states

1
EF with simple multi-particle states

• Vishnu V. Zutshi
• NIU/NICADD

2
Hadron Position Resolution

• Since Eflow invariably involves associating
  clusters near an extrapolated track
• How to do this in a digital calorimeter ?
• Study this using charged pions
• Resolution is defined w.r.t. the MC extrapolated
  position

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10 GeV charged pions
Energy weighted
unweighted
Density weighted
4
10 GeV charged pions
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Density

• Need a hierarchy in the absence of an energy
  measurement
• Clumpiness of the surrounding
• A simple-minded realization of this used here
• di S (1/dRij) where dRij is the
  angular
• distance between cell i and cell j

6
10 GeV p?
Thanks Ben
unweighted
Measured relative to the energy weighted
resolutions
Cell area at first layer0.64cm2
Density weighted
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10 GeV p?
unweighted
Measured relative to the energy weighted
resolutions
Cell area at first layer4cm2
Density weighted
8
10 GeV p?
unweighted
Measured relative to the energy weighted
resolutions
Cell area at first layer6cm2
Density weighted
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10 GeV p?
unweighted
Measured relative to the energy weighted
resolutions
Cell area at first layer9cm2
Density weighted
10
10 GeV p?
unweighted
Measured relative to the energy weighted
resolutions
Cell area at first layer12cm2
Density weighted
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10 GeV p?
unweighted
Measured relative to the energy weighted
resolutions
Cell area at first layer16cm2
Density weighted
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2GeV Photons
maxima
maxima
maxima
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Clustering

• Local density maxima chosen as seed clusters
• Membership of each cell in the seed clusters
  decided with a distance function
• Calculate centroids
• Iterate steps 2 and 3 till distortion is below
  some threshold

Could be unique or shared
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Parameters

• Cell thresholds
• How many layers to lump together
• Neighborhood for maxima search
• Minimum no. of layers hit
• Neighborhood for membership
• Proto-cluster definition
• Uniqueness of membership

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10 GeV p0
Density weighted q-f
High asymmetry
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10 GeV p0
Density weighted q-f
Medium asymmetry
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10 GeV p0
Density weighted q-f
Low asymmetry
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10 GeV p0
Density weighted q-f
Low asymmetry
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10 GeV p0
Recon. energy
Recon. mass
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10 GeV p0
Recon. energy
Recon. mass
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Energy asymmetry
A abs(Eg1 Eg2)/(Eg1 Eg2)
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S ? pp0
p
Density weighted q-f
p0
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S ? pp0
p
Density weighted q-f
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S ? pp0
Eflow
Cal only
E/Egen
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S ? np
p
EMCal
n
HCal
p
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S ? np
n
EMCal
p
HCal
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S ? np
Not reliable due to noncompensation
recE (p)
genE (p)
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S ? np

• Get the e/pi for the SD detector
• Scale the MC truth with that function
• Take the ratio of the reconstructed pion energy
  with the scaled MC truth
• This should have a mean of 1.0 (with an atrocious
  resolution) if things are working ok

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S ? np
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Summary/Outlook

• A first pass clustering/track association
  algorithm exists applicable to EM/HAD, both
  analog/digital
• Encouraging results for multiparticle events
• More detailed study to expand and enhance (for
  instance particle id)
• Move to jets
• Feedback into calorimeter design