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Track Extrapolation/Shower Reconstruction in a Digital HCAL
Steve Magill ANL
1st step - Track extrapolation thru Cal
– substitute for Cal cells in road (core + tuned outlyers)
- analog* or digital techniques in HCAL – S. Magill
– Cal granularity/segmentation optimized for separation of charged/neutral clusters
2nd step - Photon finder (use analytic long./trans. energy
profiles, ECAL shower max, etc.) – S. Kuhlmann
3rd step - Jet Algorithm on tracks and photons - Done
4th step – include remaining Cal cells (neutral hadron
energy) in jet (cone?) -> Digital HCAL?
E-flow alg. Korea, NIU, Prague
* V. Morgunov, CALOR2002
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Density-Weighted CAL Cells
cell density weight = 3/40
area ~ 40 cells
red – E fraction for density > 1/40blue – E fraction outside .04 cone
# cells in window
E-weight : analog calD-weight : digital cal
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ECAL Interaction Layer 20, Theta, Phi
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HCAL Interaction Layer 10, Theta, Phi
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Density vs E - ECAL
MIP signal – 8 MeV
cell density
cell
energ
y (
GeV
)
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Density vs E - HCAL
MIP signal – 36 MeV
what’s this?
cell
energ
y (
GeV
)
cell density
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Mokka, impact of the gas in HCALElectrons PionsGas GasScin Scin
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HCAL E fraction, Ecell > 1 MIP
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HCAL Cell Density Distribution
31% single cell windows
mean ~ 4 cells
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Seed Cell Distribution (cell density > 1)
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Track Extrapolation/Shower Link Algorithm
1. Pick up all seed cells close to extrapolated track- Can tune for optimal seed cell definition- For cone size < 0.1 (~6o), get 85% of energy
2. Add cells in a cone around each seed cell through n layers
3. Linked seed cells in subsequent cones form the reconstructed shower4. Discard all cells linked to the track
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Single 10 GeV Pion : D-weighted event display
Blue – allRed – density > 1Green – density > 3
Gap between ECAL/HCAL
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Single 10 GeV Pion – event display comparison