Transcript Progress with the Development of Energy Flow Algorithms at Argonne José Repond for Steve Kuhlmann and Steve Magill Argonne National Laboratory Linear Collider Workshop, Amsterdam,

Progress with the Development of
Energy Flow Algorithms at Argonne
José Repond
for Steve Kuhlmann and Steve Magill
Argonne National Laboratory
Linear Collider Workshop, Amsterdam, April 1 – 4, 2003
Simulation Software
Package
JAS and GIZMO
Conversion to GEANT4 soon
Detector
SD or ‘Small’ detector
Si-W ECAL
5x5 mm2
Scintillator-Fe HCAL
10x10 mm2
Track pattern recognition included
Overview of Algorithm
1st step - Track extrapolation thru Cal
– substitute for Cal cells in road (core + tuned outlyers)
- analog* or digital techniques in HCAL – S. Magill
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?)
Optimize Cal segmentation for separation of charged/neutral clusters
* V. Morgunov, CALOR2002
Track Extrapolation/Shower Link Algorithm
Define D-weight: - for every cell
- area of ~ 40 cells
- D-weight = #/40
E-weight: - simply take energy of cell
area ~ 40 cells
digital cal
analog cal
red – E fraction for density > 1/#
blue – E fraction outside area



cell density weight = 3/40
# cells in window
Response to single π with 10 GeV…
D-Weights: in ECAL at Interaction Layer 20
#events·weight
20 layers after π interacts
If D-weight:
≡ 1 Breit-Wigner
≡ n/40 Gaussian
θ
φ
D-Weights: in HCAL at Interaction Layer 10
If D-weight:
≡ 1 Breit-Wigner
≡ n/40 Gaussian
θ
φ
cell energy (GeV)
E-CAL: Energy in cell vs cell density
MIP signal
at 8 MeV
cell density n/40
H-CAL: Energy in cell vs cell density
cell energy (GeV)
what’s this?
MIP signal
at 36 MeV
Soft stuff
in
Scintillator???
cell density n/40
HCAL: analog E fraction
only sum up if Ecell ≥ 1 MIP
ΣE/10 GeV
Some losses…
Effect on energy
resolution to be
investigated…
HCAL: Cell Density (in 40 cell window)
31% single cell windows
mean ~ 4 cells
Seed Cell Distribution
defined as cell w/ cell density > 1/40
In most cases
number of seed
cells = 0
Number of seed cells
D-weights: comparison with event display
Blue – all
Red – density > 1/40
Green – density > 3/40
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 shower
4. Discard all cells linked to the track
Hadronic Z decays at √s = 91 GeV…
To develop Photon finder
Definition of EM cluster
Cluster of calorimeter energies within a cone of 0.04
No requirement on EECAL/EHCAL or EHCAL
Cuts to select photon clusters and reject anything else
I. EM clusters rejected within 0.03 of extrapolated track
within 0.01 if track MIP in all 30 layers
II. EM clusters required to have shower maximum energy > 30 MeV
(SME is sum of layers 8,9 and 10)
still needs fine tuning
III. Require Ecluster/ptrack > 0.1, if EM cluster within 0.1 of track
I. Cut on distance to track
Reject EM clusters if ΔR < 0.03
< 0.01 if MIP in all 30 layers of ECAL
Probability of overlap
of γ and track
0.1% within ΔR < 0.02
3.3% within ΔR < 0.1
11% within ΔR < 0.2
Small loss of EM clusters
II. Cut on energy at shower maximum
Require SME > 30 MeV
2 GeV e-
MeV
2 GeV -
MeV
III. Energy – momentum ratio
EM Cluster Energy/Track E
Require Ecluster/ptrack > 0.1 for ΔR <0.1
10 GeV π-
Clusters left after previous cuts
ΔR from EM Cluster to Track
Total Photon Candidate Energy
After all cuts…
Hadronic Z Decays at s = 91 GeV
Total Hadron Level Photon Energy (GeV)
Hadronic Z Decays at s = 91 GeV
μEM = 0.25 GeV
σEM = 2.8 GeV
Perfect EFA
Goal σEM = 1.4 GeV
Compare to h0 σh = 2.9 GeV
Total Photon Energy - Total Monte Carlo Photons (GeV)
Simulation of different active media
Gas Electron Multipliers
J Li, A White, J Yu: University of Texas in Arlington
Simulation of both detailed and simple GEM geometries
Single π Resolution
Resistive Plate Chambers
L Xia: Argonne National Laboratory
Summary
1.
Continuing work on implementation of algorithm
2. Tune to single particles first, then to particles in jets
3. Implement photon finder
4. Deal with neutral hadron energy
5. Compare performance to analog version (SNARK)
6. Use EFA to optimize transverse cell size of DHCAL
7. Compare performance with different active media:
Scintillator, GEMs and RPCs