Energy Flow Studies

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Energy Flow Studies
Steve Kuhlmann Argonne National Laboratory for
Steve Magill, U.S. LC Calorimeter Group
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Introduction/Outline
Detector is the Small Detector
(Si-W EM Cal, 5 mm X 5mm,
R127 cm, 17/?E) (Fe-Scint HAD Cal, 1 cm X
1cm, R144cm, 60/?E) Software is JAS2 and GIZMO
simulation Conversion to Geant4 soon Real Track
Pattern Recognition Included Will
Discuss Brief Photon Review and Plans Initial
work on the Real Challenge Neutrons/KLongs
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Resolution components of Hadronic Z Decays at ?s
91 GeV

• Assuming Perfect Identification in this Detector
  Configuration
• NeutronsKLong 2.9 GeV
• Photons 1.4 GeV
• Tracks 0.25 GeV

Put together in Tesla TDR in Energy Flow algorithm
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Hadronic Z Decay
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Simple 3 cut analysis

• Reject EM Clusters if within Delta-Rlt0.03
  from Track (0.2 loss of real photons)
• Shower Max Energy gt 30 MeV (MIP8 MeV)
• Reject EM Cluster if Delta-Rlt 0.1 AND E/Plt0.1
• Java code is available at
• www.hep.anl.gov/stk/lc/uta/
• Will be put in CVS Server soon

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Hadronic Z Decays at ?s 91 GeV
Total Photon Candidate Energy
Total Hadron Level Photon Energy (GeV)
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Hadronic Z Decays at ?s 91 GeV
Mean0.25 GeV, Width2.8 GeV, Perfect EFLOW Goal
is 1.4 GeV.
Total Photon Energy - Total Monte Carlo Photons
(GeV)
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Energy Fragments from a Single 10 GeV ?-
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Current Photon Work

1. Reject EM Clusters if within Delta-Rlt0.03
   from Track (0.2 loss of real photons)
2. Shower Max Energy gt 30 MeV (MIPS8 MeV)
3. Reject EM Cluster if Delta-Rlt 0.1 AND E/Plt0.1

Replace these two cuts with SLAC NNet-based
ClusterID package. (Worked on
technical difficulties with Bower after UTA, not
solved)
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Neutron/K0L Content of Hadronic Z Decays at ?s
91 GeV
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Neutron/K0L Energies in Hadronic Z Decays at ?s
91 GeV
Neutrons/K0L, Mean E4.35
Neutrons/K0L, Mean E4.4 GeV
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Study of gt2 GeV Neutron/K0L overlapping gt2 GeV
Tracks
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Study of gt2 GeV Neutron/K0L overlapping gt2 GeV
Tracks
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Study of gt2 GeV Neutron/K0L overlapping gt2 GeV
Tracks
Separation between Track and Closest N/K0L
Separation between N/K0L and Closest Track
Overflow bin
Overflow bin
Angular Separation (radians)
Angular Separation (radians)
10 overlap within Seplt0.2
48 overlap within Seplt0.2
23 overlap within Seplt0.4
77 overlap within Seplt0.4
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Overlapping Showers from
Other Tracks
Separation between random gt2 GeV Track and
Closest gt2 GeV Track
Angular Separation (radians)
16 overlap within Seplt0.1
59 overlap within Seplt0.3
41 overlap within Seplt0.2
72 overlap within Seplt0.4
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Single 10 GeV Charged Pions Basic Shower
Widths
Angular Separation (radians)
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Single 10 GeV Charged Pions Means and
Widths
Mean Width Width
All Hits 8.3 GeV 19 60/sqr(E)
Conelt0.4 8.1 GeV 21 67/sqr(E)
Conelt0.3 7.9 GeV 22 68/sqr(E)
Conelt0.2 7.5 GeV 22 70/sqr(E)
Conelt0.1 6.4 GeV 25 80/sqr(E)
Conelt0.075 5.8 GeV 28 88/sqr(E)
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Single 10 GeV Charged Pions
All Hits
Conelt0.2
EMHAD Energy (GeV)
EMHAD Energy (GeV)
These plots are with analog hadron cal, very
similar with digital
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Select Charged Pions isolated from other tracks
in Z Decays, look for Neutron
Overlap
No overlap from particle list
Overlapping Neutron/K0L
Cal Energy/Track P
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Two approaches being investigated
1) Put calorimeter and track properties into
neural net. List of calorimeter variables put
into ClusterID Net
2) Careful removal of track depositions from
Calorimeter. Used in European package called
Snark. Results similar to Tesla TDR, but
larger resolution tails.
Tesla TDR approach
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Reminder, the Questions we eventually need to
Answer
Detector Size and Hadron Calorimeter
Resolution? Digital or Analog Hadron
Calorimeter? Optimized segmentation for
physics/costs?
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Backup Slides
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Question from Jeju and Calor2000 Will
Hadronization or Jet Clustering Ruin Resolutions?
No, at least if backgrounds are small
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Particle Energies in Hadronic Z Decays at ?s 91
GeV
Charged, Mean E2.85
Photons, Mean E1.0
Neutrons/K0L, Mean E4.35
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Tracking cannot be assumed to be perfect,
forward tracking and curlers are issues
Effect of ignoring charged particles below
certain thresholds
Tesla TDR, is fine if achieved
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Track Reconstruction Efficient Down to Pt0.5 GeV
in Barrel Region
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Single 10 GeV ?-
EM Clustering -- Cone 0.04
EM Cluster Energy (GeV)
Delta-R from EM Cluster to Track
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Reduce charged particle fragments with 3-layer
shower max energy gt 30 MeV
ddd
Also reduces neutron/K0L clusters
2 GeV Electron
ddd
2 GeV ?-
MeV
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Single 10 GeV ?-
Now With Shower Max Cut, will be improved with
more detailed information on lateral/longitudinal
profile
EM Cluster Energy (GeV)
Delta-R from EM Cluster to Track
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Effect of possible Photon threshold on Hadronic Z
Decays at ?s 91 GeV
Photons are soft, Mean E1.0
Sum of all Hadron Level energy except photons lt
0.2 GeV. Wont apply such a cut (yet).
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Hadronic Z Decays at ?s 91 GeV
Simple photon finder Remove EM Clusters within
0.03 of Track, unless track was MIP in all 30
layers. Then remove if within 0.01.
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Hadronic Z Decays at ?s 91 GeV
Probability of Overlapping Photon Close to a
Track, 0.1 within DRlt0.02, 3.3 within
DRlt0.1, 11 within DRlt0.2
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Determining Charged Particle Depositions

• Easy to recognize MIP
• Easy to determine 1st layer of pion shower

Energy deposited in last EM layer (within 0.60
of track)
Interactions
Overflows
Zeros
Tail
Single 2 GeV ?-
Single 2 GeV Muon
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Determining Charged Particle Depositions
Single 2 GeV ?-
Energy weighted
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Effect of Neutrinos in Hadronic Z Decays
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One more cut motivated by Single 10 GeV ?-, now
either an Energy Ratio
EM Cluster Energy/Track E
Delta-R from EM Cluster to Track