Simulation of CMS Phase 2 Pixel Tracker for HL-LHC Bahareh - PowerPoint PPT Presentation

FERMILAB-SLIDES-18-069-CMS This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Simulation of CMS Phase 2 Pixel Tracker for HL-LHC Bahareh Roozbahani USCMS FPIX Simulation Group June 18, 2018

Introduction ◮ CMS pixel detector is a unique tracking detector → All-silicon technology → Key element in efficient and precise reconstruction of tracks/interaction vertices and heavy flavor tagging H → ZZ → ee µµ ◮ Tracker is the closest to the beam-line → Difficult environment event above, overlaid with 20 pileup interactions → High instantaneous luminosity ( ∼ 10 34 cm − 2 s − 1 ) ROC high rates → Large number of pp interactions per bunch- Accumulated radiation Damage crossing (pileup) Decreased in charge collection/sharing → Expecting increase in instantaneous luminosity, pileup up to 140 to 200 at HL-LHC Worsen efficiency and resolution New Perspectives 2018 June 18, 2018 1/10

CMS Pixel Detector Upgrade 13 Phase1 pixel detector installation Phase2 pixel detector installation Phase0 → Phase1 ◮ Added extra barrel layer and endcap disk ◮ Layers closer to the beam-line → improvement in tracking and b-tagging ◮ Barrel: 48M → 79M pixels Forward: 18M → 45M pixels ◮ Moved from analog to digital readout New Perspectives 2018 June 18, 2018 2/10

CMS Pixel Detector Phase2 Upgrade ◮ Inner Tracker (Pixel Detector): → Same number of Barrel layers (4) as the current detector → Increase the endcap disks to 12 disks Better η coverage → | η | < 4 . 0 Improved tracking/vertexing Better mitigation of pileup → Increasing granularity/smaller pixels (x6 smaller pixel area) Improved resolution Maintain low digi occupancy New Perspectives 2018 June 18, 2018 3/10

Simulation and Digitization ◮ 1) Simulation of the detector geometry using tkLayout → geometry A : 4 barrel layer, 12 endcap disks 25x100x150 µ m 3 pixels → geometry B : 4 barrel layer, 12 endcap disks 50x50x150 µ m 3 pixels ◮ 2) Simulation of desired physics processes using particle gun (Pythia8) and Detector response (Geant4) → Ten Muon process with 200 pileup overlaid, simulated in geometry A and geometry B → Output is a collection of simulated hits ◮ 3) Digitization (CMSSW) → Convert simulated hits to format similar to experimental raw data (digis) New Perspectives 2018 June 18, 2018 4/10

Occupancy Study Digi Occupancy vs. η Digi Charge in Barrel Digi Charge in Endcap CMS Simulation (14 TeV) CMS Simulation (14 TeV) CMS Simulation (14 TeV) × 10 3 × 10 3 Digi Occupancy 0.003 Layer_1 Layer_1 Layer_1 Layer_1 Disc_1 µ 25x100 m 2 Barrel Layer_1 Layer_1 Layer_1 Layer_1 FPIX1 Disc_1 Disc_1 Disc_1 Disc_1 Layer_2 Layer_2 Layer_2 Layer_2 Disc_4 6000 3000 Layer_2 Layer_2 Layer_2 Layer_2 Disc_2 Disc_2 Disc_2 Disc_2 Layer_3 Layer_3 Layer_3 Layer_3 Disc_8 0.0025 µ 2 µ 2 25x100 m 25x100 m Layer_3 Layer_3 Layer_3 Layer_3 Disc_3 Disc_3 Disc_3 Disc_3 Layer_4 Layer_4 Layer_4 Layer_4 Disc_12 5000 2500 25x100 µ m 2 pixels Layer_4 Layer_4 Layer_4 Layer_4 Disc_4 Disc_4 Disc_4 Disc_4 0.002 4000 2000 0.0015 3000 1500 0.001 2000 1000 0.0005 1000 500 0 0 0 − 5 − 4 − 3 − 2 − 1 0 1 2 3 4 5 0 5 10 15 20 25 0 5 10 15 20 25 η Charge of Digis Charge of Digis CMS Simulation (14 TeV) × 3 CMS Simulation (14 TeV) × 3 CMS Simulation (14 TeV) 10 10 Digi Occupancy Layer_1 Layer_1 Layer_1 Layer_1 Disc_1 0.004 7000 µ 50x50 m 2 Barrel Layer_1 Layer_1 Layer_1 Layer_1 FPIX1 Disc_1 Disc_1 Disc_1 Disc_1 Layer_2 Layer_2 Layer_2 Layer_2 Disc_4 3000 0.0035 Layer_2 Layer_2 Layer_2 Layer_2 Disc_2 Disc_2 Disc_2 Disc_2 Layer_3 Layer_3 Layer_3 Layer_3 Disc_8 6000 50x50 µ m 2 50x50 µ m 2 50x50 µ m 2 pixels Layer_3 Layer_3 Layer_3 Layer_3 Disc_3 Disc_3 Disc_3 Disc_3 Layer_4 Layer_4 Layer_4 Layer_4 Disc_12 2500 0.003 5000 Layer_4 Layer_4 Layer_4 Layer_4 Disc_4 Disc_4 Disc_4 Disc_4 0.0025 2000 4000 0.002 1500 3000 0.0015 1000 2000 0.001 500 1000 0.0005 0 0 0 − − − − − 5 4 3 2 1 0 1 2 3 4 5 0 5 10 15 20 25 0 5 10 15 20 25 η Charge of Digis Charge of Digis ◮ Higher digi occupancy in the barrel for 50x50 µ m 2 comparing to 25x100 µ m 2 ◮ Larger charge collection in 50x50 µ m 2 in the barrel, similar deposition in endcap New Perspectives 2018 June 18, 2018 5/10

Track Reconstruction ◮ step 2) Track Reconstruction ◮ step 1) Local Reconstruction → Inputs are RecHits → Clustering adjacent pixel digis that are above certain threshold with 2 dimensional matrix algorithm → combinatory track finder (CTF) algorithm, combines reconstructed hits into tracks iteratively → Inputing clustered digis in a position estimator algorithm that take into account Lorentz drift to produce point measurements (RecHits) New Perspectives 2018 June 18, 2018 6/10

Track transverse impact parameter ( d xy ) Resolution CMS Simulation (14 TeV) CMS Simulation (14 TeV) 0.03 )(cm) 25x100 η 25x100 0.0< <0.4 ≤ xy 0.025 10 p (GeV) < 50 ± 50x50 RMS = 0.00089 0.00000 1 (d T η 0.0 < < 0.4 σ 0.02 50x50 ± RMS = 0.00103 0.00001 0.015 0 . 0 < η < 0 . 4 − 1 0.01 10 0.005 0 − 10 2 50x50/25x100 50x50 1.5 25x100 1 0.5 − 10 3 − − − − 20 40 60 80 100 120 0.02 0.015 0.01 0.005 0 0.005 0.01 0.015 0.02 p (GeV) T Reco TP d -d xy xy CMS Simulation (14 TeV) CMS Simulation (14 TeV) 0.03 )(cm) 25x100 η 1 25x100 2.5< <3.0 0.025 ≤ ± xy 10 p (GeV) < 50 RMS = 0.00145 0.00000 50x50 (d T η 2.5 < < 3.0 σ 0.02 50x50 RMS = 0.00186 ± 0.00000 0.015 2 . 5 < η < 3 . 0 − 10 1 0.01 0.005 0 − 2 10 50x50/25x100 50x50 1.5 25x100 1 0.5 − 3 10 20 40 60 80 100 120 − − − − 0.02 0.015 0.01 0.005 0 0.005 0.01 0.015 0.02 p (GeV) T d Reco -d TP xy xy ◮ d xy Resolution is worse in 50x50 µ m 2 geometry, particularly at high p T New Perspectives 2018 June 18, 2018 7/10

Track longitudal impact parameter ( d z ) Resolution CMS Simulation (14 TeV) CMS Simulation (14 TeV) 0.03 )(cm) 25x100 η 25x100 0.0< <0.4 ≤ z 0.025 10 p (GeV) < 50 ± (d 50x50 RMS = 0.00228 0.00001 T 1 η σ 0.0 < < 0.4 0.02 50x50 ± RMS = 0.00121 0.00001 0.015 0 . 0 < η < 0 . 4 0.01 − 1 10 0.005 0 10 − 2 50x50/25x100 50x50 1.5 25x100 1 0.5 − 10 3 − − − 20 40 60 80 100 120 0.06 0.04 0.02 0 0.02 0.04 0.06 p (GeV) T Reco TP d -d z z CMS Simulation (14 TeV) CMS Simulation (14 TeV) 0.05 )(cm) 25x100 0.045 η 25x100 2.5< <3.0 ≤ ± z 10 p (GeV) < 50 RMS = 0.01156 0.00003 (d 0.04 50x50 T η σ 2.5 < < 3.0 0.035 50x50 − 10 1 0.03 RMS = 0.00898 ± 0.00002 0.025 2 . 5 < η < 3 . 0 0.02 0.015 0.01 0.005 10 − 2 0 50x50/25x100 50x50 1.5 25x100 1 0.5 − 3 10 20 40 60 80 100 120 − − − 0.06 0.04 0.02 0 0.02 0.04 0.06 p (GeV) T d Reco -d TP z z ◮ d z Resolution is better in 50x50 µ m 2 geometry, specially for higher p T tracking particles New Perspectives 2018 June 18, 2018 8/10

Track p T Resolution CMS Simulation (14 TeV) CMS Simulation (14 TeV) 0.03 ) T /p 25x100 1 T η 25x100 p 0.0< <0.4 ≤ 0.025 10 p (GeV) < 50 ± 50x50 RMS = 0.00723 0.00004 δ T ( η σ 0.0 < < 0.4 0.02 50x50 ± RMS = 0.00714 0.00004 0.015 0 . 0 < η < 0 . 4 − 10 1 0.01 0.005 0 − 2 10 50x50/25x100 50x50 1.5 25x100 1 0.5 − 10 3 − − − 20 40 60 80 100 120 0.15 0.1 0.05 0 0.05 0.1 0.15 p (GeV) p Reco -p TP T T T TP p T CMS Simulation (14 TeV) CMS Simulation (14 TeV) 0.06 ) T 25x100 /p η 25x100 T 2.5< <3.0 p 0.05 ≤ ± 10 p (GeV) < 50 RMS = 0.03460 0.00008 50x50 δ T η ( 10 − 1 2.5 < < 3.0 σ 0.04 50x50 RMS = 0.03639 ± 0.00008 0.03 2 . 5 < η < 3 . 0 0.02 0.01 − 2 10 0 50x50/25x100 50x50 1.5 25x100 1 0.5 − 3 10 20 40 60 80 100 120 − − − 0.15 0.1 0.05 0 0.05 0.1 0.15 p (GeV) Reco p -p TP T T T p TP ◮ d p T Resolution is similar for 25x100 µ m 2 and 50x50 µ m 2 geometry, slightly T worsen for higher p T in 50x50 µ m 2 New Perspectives 2018 June 18, 2018 9/10

Summary ◮ We have studied the pixel detector performance for 2 scenarios: → 25x100 µ m 2 pixel size → 50x50 µ m 2 pixel size ◮ Digi occupancy is somewhat higher in barrel for 50x50 µ m 2 ◮ Larger charge collection in 50x50 µ m 2 comparing to 25x100 µ m 2 ◮ d xy resolutions are worse for 50x50 µ m 2 in most η bins ◮ d z resolutions are better for 50x50 µ m 2 in most η bins ◮ p T resolutions are are similar for 50x50 µ m 2 and 25x100 µ m 2 at low p T , but becomes worse for 50x50 µ m 2 at p T > 100 GeV. New Perspectives 2018 June 18, 2018 10/10

Backup Slides New Perspectives 2018 June 18, 2018 11/10