Fast Simulation of Calorimeter Punch-Through Particles in ATLAS A - - PowerPoint PPT Presentation

Fast Simulation of Calorimeter Punch-Through Particles in ATLAS

A Status Report Elmar Ritsch (University of Innsbruck) Andreas Salzburger (CERN) Emmerich Kneringer (University of Innsbruck) September 9, 2010

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 1 / 15

The ATLAS Experiment

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 2 / 15

Event Simulation Scheme in ATLAS

FATRAS, the fast Simulation

FATRAS (Fast ATLAS TRack Simulation) based on simulating particle tracks in a simplified detector geometry ∼ 100 times faster than full Geant4 based simulation implementation of this work is done in FATRAS

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 3 / 15

What is Calorimeter Punch-Through?

⇒ only muons should create signals in the muon spectrometer (MS) ⇒ signals in the MS are mostly interpreted as muons

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 4 / 15

What is Calorimeter Punch-Through?

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 5 / 15

What is Calorimeter Punch-Through?

Geant4 based Simulation

single pion

• rigin: collision point

low energy

Event with Calorimetric Confinement

pion and daughter particles stopped in the calorimeter

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 5 / 15

What is Calorimeter Punch-Through?

Geant4 based Simulation

single pion

• rigin: collision point

high energy

Punch-Through Event

daughter particles reach the MS punch-through particles can create fake muon tracks in the MS interesting!!

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 5 / 15

The fake-muon tracks measured in the MS due to punch-through particles are background

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 6 / 15

Punch-Through Particles

Geant4 based, Single Pion Simulations

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 7 / 15

Definition of Punch-Through

Relevant Definition of Punch-Through for Fast Simulation

Punch-Through ⇔ at least one photon, muon, proton, electron, pion (or kaon) enters the MS if a particle other than a muon or neutrino entered the calorimeter

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 8 / 15

What causes Calorimeter Punch-Through

Main Dependencies of Punch-Through Occurrences

energy of particle when entering the calorimeter interaction-length in the calorimeter along the particle’s track

Geant4 based, Single Pion Simulations

pion energy (MeV) 50 100 150 200 250 300 350 400 450 500

3

10 × punch-through probability 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Punch-Through Probability vs Energy

• f pion

η pseudorapidity 0.2 0.4 0.6 0.8 1 1.2 1.4 punch-through probability 0.1 0.15 0.2 0.25 0.3 η Punch-Through Probability vs

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 9 / 15

Implementation of a Fast Punch-Through Simulation

Approach

1

do lots of time consuming Geant4 single particle simulations

2

treat each punch-through particle type separately (muon, pion, electron, ...)

3

for each of these particles draw most important properties, depending on different incoming particle properties (Energy, η)

4

fit generic function to these distributions and store the fit parameters

5

reproduce these distributions in FATRAS

6

implement most important correlations between the different particle types

Most Important Properties of Punch-Through Particles

number of particles entering the MS energy distribution of these deflection angles ∆Θ and ∆Φ relative to the incoming particle

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 10 / 15

Properties of Punch-Through Particles: e.g. Pions

Number of Punch-Through Pions 10 20 30 40 50 60 70 Probability

• 4

10

• 3

10

• 2

10

• 1

10 1

Geant4 Fit

Energy of Punch-Through Pions (MeV) 20 40 60 80 100 120 140 160 180 200

3

10 × Probability

• 4

10

• 3

10

• 2

10

• 1

10 1

Geant4 Fit

φ ∆ 0.05 0.1 0.15 0.2 0.25 Probability

• 4

10

• 3

10

• 2

10

• 1

10

Geant4 Fit

θ ∆ 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 Probability

• 4

10

• 3

10

• 2

10

Geant4 Fit

→ for different energies and η of incoming particles → for different η of incoming particles and energies of punch-through particle itself

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 11 / 15

FATRAS Simulation of Punch-Through

Number of Particles Penetrating the MS 5 10 15 20 25 30 Relative Frequency

• 4

10

• 3

10

• 2

10

• 1

10 1 Energy of Punch-Through Particles (MeV) 50 100 150 200 250 300 350 400 450 500

3

10 × Relative Frequency

• 6

10

• 5

10

• 4

10

• 3

10

• 2

10

• 1

10 1 φ ∅ 0.2 0.4 0.6 0.8 1 1.2 Relative Frequency

• 5

10

• 4

10

• 3

10

• 2

10

• 1

10 1 ∆ θ ∅ 0.1 0.2 0.3 0.4 0.5 0.6 Relative Frequency

• 4

10

• 3

10

• 2

10

• 1

10 1 ∆

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 12 / 15

FATRAS Simulation of Punch-Through: Correlation

Correlation: Electrons – Photons

Number of Punch-Through Photons 10 20 30 40 50 60 70 Number of Punch-Through Electrons 10 20 30 40 50 60 70 g4_corr11_22 Entries 932915 Mean x 0.05103 Mean y 0.03877 RMS x 0.5125 RMS y 0.3937 1 10

2

10

3

10

4

10

5

10 g4_corr11_22 Entries 932915 Mean x 0.05103 Mean y 0.03877 RMS x 0.5125 RMS y 0.3937 Number of Punch-Through Photons 10 20 30 40 50 60 70 Number of Punch-Through Electrons 10 20 30 40 50 60 70 fatras_corr11_22 Entries 369456 Mean x 0.0484 Mean y 0.03577 RMS x 0.4925 RMS y 0.3734 1 10

2

10

3

10

4

10

5

10 fatras_corr11_22 Entries 369456 Mean x 0.0484 Mean y 0.03577 RMS x 0.4925 RMS y 0.3734

FATRAS

Correlation: Protons – Pions

Number of Punch-Through Protons 10 20 30 40 50 60 70 Number of Punch-Through Pions 10 20 30 40 50 60 70 g4_corr2212_211 Entries 932915 Mean x 0.1746 Mean y 0.3085 RMS x 0.7298 RMS y 1.362 1 10

2

10

3

10

4

10

5

10 g4_corr2212_211 Entries 932915 Mean x 0.1746 Mean y 0.3085 RMS x 0.7298 RMS y 1.362

Geant4

Number of Punch-Through Protons 10 20 30 40 50 60 70 Number of Punch-Through Pions 10 20 30 40 50 60 70

fatras_corr2212_211

Entries 369456 Mean x 0.1662 Mean y 0.2927 RMS x 0.7124 RMS y 1.32 1 10

2

10

3

10

4

10

5

10

fatras_corr2212_211

Entries 369456 Mean x 0.1662 Mean y 0.2927 RMS x 0.7124 RMS y 1.32

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 13 / 15

FATRAS Simulation of Punch-Through: Overall Results

pion energy (MeV) 50 100 150 200 250 300 350 400 450 500

3

10 × punch-through probability 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Punch-Through Probability vs Energy

• f pion

η pseudorapidity 0.2 0.4 0.6 0.8 1 1.2 1.4 punch-through probability 0.1 0.15 0.2 0.25 0.3 η Punch-Through Probability vs Number of Tracks in MS 5 10 15 20 25 30 relative frequency

• 6

10

• 5

10

• 4

10

• 3

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• 2

10

• 1

10 1

Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 14 / 15

Summary and Next Steps

Summary

implementation of fast punch-through simulation in FATRAS is working well good agreement with Geant4 full simulation

Next Steps

study of track-parameters (momentum, position, ...) in the MS caused by punch-through particles comparison of FATRAS punch-through simulation with collision data

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