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HCal Simulation with Geant4

1.44 mm. 1.76 mm. HCal Simulation with Geant4. 6/5/2008 M. Konno. 1. ALICE EMCal Setup. Particle:  + , e + (E in = 10 GeV) Processes: - Decays - EM interaction - Hadronic interaction (Model: LHEP_BERT) Items: - Efficiency - Energy loss (<E>, resolution)

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HCal Simulation with Geant4

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  1. 1.44 mm 1.76 mm HCal Simulation with Geant4 6/5/2008 M. Konno 1. ALICE EMCal Setup Particle: + , e+(Ein = 10 GeV) Processes: - Decays - EM interaction - Hadronic interaction (Model: LHEP_BERT) Items: - Efficiency - Energy loss (<E>, resolution) - Shower profile (transverse) - Eloss Sampling (e/ separation) 2000 mm (Z) 2000 mm (Y) 246.4 mm (X) • - 77 layers • 1 layer = 3.20 mm Absorber (Pb) Scintillator * Transverse size is enlarged for this study (single particle).

  2. 2. Eloss sampling EM Shower e+ Hadronic Shower π+ E: total * Just a schematic. E: hadronic

  3. 3. Shower profile dE/dx vs. x dEdr/ vs. r * Including everything (“shower” + “no shower”)

  4. 4. Energy loss in calorimeter Hadronic shower: 52% (Eloss>50 MeV) Etot Ehad (90%) EM shower: 100%

  5. 4. Energy loss in calorimeter Ehad (70%) Ehad (50%)

  6. 4. Energy loss in calorimeter Ehad (30%) Ehad (10%)

  7. 5. Energy loss and resolution (Eloss>50MeV) Average Eloss RMS/Mean Energy resolution: ~3 % for EM shower ~50% for hadronic shower Etot

  8. 6. Energy loss - correlation Etot vs. Ehad (90%) Etot vs. Ehad (70%)

  9. 6. Energy loss - correlation mainly hadronic part? => look at Ehad/Etot ratio Etot vs. Ehad (50%) Etot vs. Ehad (30%)

  10. 6. Energy loss - correlation Etot vs. Ehad (10%)

  11. 7. Ehad/Etot Ratio Ehad (90%) / Etot Ehad (70%) / Etot

  12. 7. Ehad/Etot Ratio Ionization (peak: ~50%) EM shower Ehad (50%) / Etot Ehad (30%) / Etot Hadronic shower (broad distribution)

  13. 7. Ehad/Etot Ratio Ehad (10%) / Etot

  14. 8. e/π separation e/π separation: Using Ehad/Etot ratio with a certain threshold. (e.g. Ehad/Etot > 0.5) => Efficiencies are calculated for e and π. • Try a tighter cut • (see next slide) Efficiency vs. L(had)/L(tot) Eff.(π)/Eff.(e) vs. L(had)/L(tot)

  15. 8. e/π separation Increased but eff. is somewhat low Efficiency vs. L(had)/L(tot) Eff.(π)/Eff.(e) vs. L(had)/L(tot)

  16. 9. Summary • ALICE EMCal setup for HCal. • Energy resolution (Etot): • ~3 % for EM shower • ~50 % for hadronic shower • Ehad/Etot ratio used to separate e and π. • Lhad/Ltot should be lower for the separation. • There may be a limit due to worse energy resolution. • (Lhad/Ltot is still OK for use.)

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