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

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

ECAL Interaction Layer 20, Theta, Phi

HCAL Interaction Layer 10, Theta, Phi

Density vs E - ECAL

MIP signal – 8 MeV

cell density

cell

energ

y (

GeV

)

Density vs E - HCAL

MIP signal – 36 MeV

what’s this?

cell

energ

y (

GeV

)

cell density

Mokka, impact of the gas in HCALElectrons PionsGas GasScin Scin

HCAL E fraction, Ecell > 1 MIP

HCAL Cell Density Distribution

31% single cell windows

mean ~ 4 cells

Seed Cell Distribution (cell density > 1)

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

Single 10 GeV Pion : D-weighted event display

Blue – allRed – density > 1Green – density > 3

Gap between ECAL/HCAL

Single 10 GeV Pion – event display comparison