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Detector Optimization using Particle Flow Algorithm for ILC

This paper presents the particle flow algorithm (PFA) used in the GLD detector for the International Linear Collider (ILC) experiment. The PFA is crucial for achieving high energy resolution and accurate particle reconstruction. Results of the algorithm's performance are discussed.

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Detector Optimization using Particle Flow Algorithm for ILC

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  1. Detector Optimization using Particle Flow Algorithm for ILC Contents 1. Introduction 2. Particle Flow Algorithm 3. Results 4. Summary DPF2006+JPS2006 @ Sheraton Waikiki Hotel Oct. 29th-Nov. 3rd, 2006 Tamaki Yoshioka ICEPP, Univ. of Tokyo On behalf of GLD Colleagues JPS2006 @ Sheraton Waikiki Hotel

  2. Introduction • Most of the important physics processes to be studied in the ILC • experiment have multi-jets in the final state. • → Jet energy resolution is the key in the ILC physics. • The best energy resolution is obtained by reconstructing • momenta of individual particles avoiding double counting among • Trackers and Calorimeters. • - Charged particles (~60%) measured by Tracker. • - Photons (~30%) by electromagnetic CAL (ECAL). • - Neutral hadrons (~10%) by ECAL + hadron CAL (HCAL). • → Particle Flow Algorithm (PFA) • In this talk, general scheme and performance of the GLD-PFA, • using the GEANT4-based full simulator (Jupiter),will be presented. JPS2006 @ Sheraton Waikiki Hotel

  3. GLD Detector Muon detector • - One of the detector concepts • for the ILC experiment. • The world-wide consensus of • the performance goal for the • jet energy resolution is • For more detail, please • see the GLD Detector • Outline Document (DOD) • → physics/0607154 Calorimeter Coil Vertex detector Tracker GLD detector JPS2006 @ Sheraton Waikiki Hotel

  4. GLD Detector Concept • To get good energy resolution by PFA, separation of particles (reducing the • density of charged and neutral particles at CAL surface) is important. Often quoted “Figure of Merit” B : Magnetic field R : CAL inner radius σ: CAL granularity RM : Effective Moliere length • GLD concept • 1. Large inner radius of ECAL to optimize the PFA. • 2. Large tracker for excellent dpt/pt2 and pattern recognition. • 3. Moderate B field (~3T). JPS2006 @ Sheraton Waikiki Hotel

  5. GLD Geometry in Jupiter Solenoid TPC Hadron Calorimeter (HCAL) VTX, IT Muon Detector Electromagnetic Calorimeter (ECAL) Dodecagonal Shape As of October 06 JPS2006 @ Sheraton Waikiki Hotel

  6. Calorimeter Geometry in Jupiter Readout Line =10cm 349.4cm Barrel HCAL 229.8cm Barrel ECAL 210cm 270cm Endcap HCAL Barrel.InnerRadius=210cm Endcap ECAL Endcap.InnerRadius=40cm IP Barrel.HalfZ=280cm 419.4cm 280cm 299.8cm JPS2006 @ Sheraton Waikiki Hotel

  7. Calorimeter Structure Active Layer Absorber Current cell size : 2x2cm Can be changed. ECAL W/Scinti./Gap 3/2/1 (mm) x 33 layers HCAL Fe/Scinti./Gap 20/5/1 (mm) x 46 layers JPS2006 @ Sheraton Waikiki Hotel

  8. Z-pole Event Display End View Side View - Z → qq (uds) @ 91.2GeV, tile calorimeter, 2cm x 2cm tile size JPS2006 @ Sheraton Waikiki Hotel

  9. Particle Flow Algorithm for GLD Flow of GLD-PFA • Photon Finding • Charged Hadron Finding • Neutral Hadron Finding • Satellite Hits Finding • *Satellite hits = calorimeter hit cell which does not belong • to a cluster core Note : Monte-Carlo truth information is used for muon and neutrino. JPS2006 @ Sheraton Waikiki Hotel

  10. Photon Likelihood - Five variables are selected to form the photon likelihood function. Velocity Mean Layer Track Distance Photon Other Output chi2 Edep/Nhits Other Photon JPS2006 @ Sheraton Waikiki Hotel

  11. Particle Flow Algorithm for GLD Flow of GLD-PFA • Photon Finding • Charged Hadron Finding • Neutral Hadron Finding • Satellite Hits Finding • *Satellite hits = calorimeter hit cell which does not belong • to a cluster core Note : Monte-Carlo truth information is used for muon and neutrino. JPS2006 @ Sheraton Waikiki Hotel

  12. Charged Hadron Finding • Basic Concept : • Extrapolate a charged track and calculate a distance between • a calorimeter hit cell and the extrapolated track. Connect the cell • that in a certain tube radius (clustering). Extrapolated Track • Calculate the distance • for any track/calorimeter • cell combination. HCAL Tube Radius Hit Cells • Tube radius for ECAL • and HCAL can be changed • separately. distance ECAL Calorimeter input position Charged Track JPS2006 @ Sheraton Waikiki Hotel

  13. Particle Flow Algorithm for GLD Flow of GLD-PFA • Photon Finding • Charged Hadron Finding • Neutral Hadron Finding • Satellite Hits Finding • *Satellite hits = calorimeter hit cell which does not belong • to a cluster core Note : Monte-Carlo truth information is used for muon and neutrino. JPS2006 @ Sheraton Waikiki Hotel

  14. Neutral Hadron Likelihood - Four variables are selected to form the NHD likelihood function. Output Velocity Energy Density Neutral Hadron Satellite Hits Edep/Nhits Mean Layer Neutral Hadron Satellite Hits JPS2006 @ Sheraton Waikiki Hotel

  15. Particle Flow Algorithm for GLD Flow of GLD-PFA • Photon Finding • Charged Hadron Finding • Neutral Hadron Finding • Satellite Hits Finding • *Satellite hits = calorimeter hit cell which does not belong • to a cluster core Note : Monte-Carlo truth information is used for muon and neutrino. JPS2006 @ Sheraton Waikiki Hotel

  16. e+ e- Yellow : Photon Red,Green : Charged Hadron Black,Blue : Neutral Hadron Z → qqbar @ 91.2GeV Event Display JPS2006 @ Sheraton Waikiki Hotel Next: 電子、陽電子衝突

  17. Event Display Yellow : Photon Red,Green : Charged Hadron Black,Blue : Neutral Hadron Gamma Finding JPS2006 @ Sheraton Waikiki Hotel

  18. Event Display Yellow : Photon Red,Green : Charged Hadron Black,Blue : Neutral Hadron Charged Hadron Finding JPS2006 @ Sheraton Waikiki Hotel

  19. Event Display Yellow : Photon Red,Green : Charged Hadron Black,Blue : Neutral Hadron Remove Satellite Hits JPS2006 @ Sheraton Waikiki Hotel

  20. Event Display Yellow : Photon Red,Green : Charged Hadron Black,Blue : Neutral Hadron Remaining : Neutral Hadron JPS2006 @ Sheraton Waikiki Hotel

  21. Jet Energy Resolution (Z-pole) - Z → uds @ 91.2GeV, tile calorimeter, 2cm x 2cm tile size All angle • Almost no angular dependence : 31%/√E for |cosq|<0.9. • cf. 60 %/√E w/o the PFA (sum up the calorimeter energy) JPS2006 @ Sheraton Waikiki Hotel

  22. Performance - Energy-weighted Efficiency and Purity Definition Efficiency : xxx  (total xx E in collected hits)/(true xxx total E in CAL) Purity : Pxxx (total xxx E in a cluster)/(total E in a cluster) xxx = Photon, CHD, NHD, Satellite both  and P values are energy-weighted JPS2006 @ Sheraton Waikiki Hotel

  23. Jet Energy Resolution - Energy dependence of jet energy resolution. - Jet energy resolution linearly degrades. → Need to improve. JPS2006 @ Sheraton Waikiki Hotel

  24. Summary • Realistic PFA has been developed using the GEANT-4 based full simulator of the GLD detector. • Jet energy resolution is studied by using Z→qq events. ILC goal of 30% has been achieved in the barrel region of the Z-pole events. • By using the PFA, we are going to optimize the detector parameters such as the calorimeter granularity, radius etc. JPS2006 @ Sheraton Waikiki Hotel

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