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 origin: 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 origin: 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 Punch-Through Probability vs Energy Punch-Through Probability vs η punch-through probability punch-through probability 0.35 0.3 0.3 0.25 0.25 0.2 0.2 0.15 0.15 0.1 0.05 0.1 3 × 10 0 0 50 100 150 200 250 300 350 400 450 500 0 0.2 0.4 0.6 0.8 1 1.2 1.4 pseudorapidity of pion pion energy (MeV) η Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 9 / 15

Implementation of a Fast Punch-Through Simulation Approach do lots of time consuming Geant4 single particle simulations 1 treat each punch-through particle type separately (muon, pion, electron, ...) 2 for each of these particles draw most important properties , depending on 3 different incoming particle properties (Energy, η ) fit generic function to these distributions and store the fit parameters 4 reproduce these distributions in FATRAS 5 implement most important correlations between the different particle types 6 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 Probability Probability 1 → for different 1 Geant4 Geant4 Fit Fit energies and η of -1 10 10 -1 incoming -2 10 10 -2 particles -3 10 -3 10 -4 10 -4 10 3 10 × 0 10 20 30 40 50 60 70 20 40 60 80 100 120 140 160 180 200 Number of Punch-Through Pions Energy of Punch-Through Pions (MeV) Probability Probability → for different η of Geant4 Geant4 10 -1 Fit Fit -2 incoming 10 -2 10 particles and 10 -3 10 -3 energies of -4 10 punch-through 10 -4 particle itself 0 0.05 0.1 0.15 0.2 0.25 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 ∆ φ ∆ θ Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 11 / 15

FATRAS Simulation of Punch-Through Relative Frequency Relative Frequency 1 1 -1 10 -1 10 10 -2 10 -2 -3 10 -4 10 -3 10 -5 10 -4 10 3 10 10 -6 × 0 5 10 15 20 25 30 0 50 100 150 200 250 300 350 400 450 500 Number of Particles Penetrating the MS Energy of Punch-Through Particles (MeV) 1 Relative Frequency Relative Frequency 1 10 -1 10 -1 10 -2 10 -2 -3 10 10 -3 -4 10 -4 10 -5 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.2 0.4 0.6 0.8 1 1.2 ∅ ∆ θ ∆ ∅ φ Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 12 / 15

FATRAS Simulation of Punch-Through: Correlation Correlation: Electrons – Photons 70 70 Number of Punch-Through Electrons Number of Punch-Through Electrons g4_corr11_22 g4_corr11_22 fatras_corr11_22 fatras_corr11_22 FATRAS 5 Entries Entries 932915 932915 Entries Entries 369456 369456 10 Mean x Mean x 0.0484 0.0484 60 Mean x 0.05103 Mean x 0.05103 5 60 10 Mean y 0.03877 Mean y 0.03877 Mean y 0.03577 Mean y 0.03577 RMS x RMS x 0.5125 0.5125 RMS x RMS x 0.4925 0.4925 10 4 50 50 RMS y RMS y 0.3734 0.3734 RMS y RMS y 0.3937 0.3937 10 4 40 40 3 10 10 3 30 30 10 2 2 10 20 20 10 10 10 10 0 0 1 1 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 Number of Punch-Through Photons Number of Punch-Through Photons Correlation: Protons – Pions 70 70 Number of Punch-Through Pions Number of Punch-Through Pions g4_corr2212_211 g4_corr2212_211 fatras_corr2212_211 fatras_corr2212_211 Geant4 5 Entries Entries 932915 932915 10 Entries Entries 369456 369456 60 Mean x Mean x 0.1746 0.1746 5 60 Mean x Mean x 0.1662 0.1662 10 Mean y Mean y 0.3085 0.3085 Mean y Mean y 0.2927 0.2927 RMS x RMS x 0.7298 0.7298 RMS x RMS x 0.7124 0.7124 10 4 50 RMS y RMS y 1.362 1.362 50 RMS y RMS y 1.32 1.32 10 4 40 40 3 10 3 10 30 30 10 2 10 2 20 20 10 10 10 10 0 1 0 1 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 Number of Punch-Through Protons Number of Punch-Through Protons Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 13 / 15

FATRAS Simulation of Punch-Through: Overall Results Punch-Through Probability vs Energy Punch-Through Probability vs η punch-through probability punch-through probability 0.3 0.35 0.3 0.25 0.25 0.2 0.2 0.15 0.15 0.1 0.05 0.1 3 10 × 0 0 50 100 150 200 250 300 350 400 450 500 0 0.2 0.4 0.6 0.8 1 1.2 1.4 pion energy (MeV) pseudorapidity of pion η relative frequency 1 10 -1 -2 10 -3 10 -4 10 -5 10 -6 10 0 5 10 15 20 25 30 Number of Tracks in MS 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 Elmar Ritsch (Innsbruck) Fast Simulation of Punch-Through in ATLAS September 9, 2010 15 / 15