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Reconstructing Upsilons in di-muon channel in HI Events

Reconstructing Upsilons in di-muon channel in HI Events. Sasha Lebedev and Marzia Rosati. Iowa State University. Immediate Goal: Study reconstruction efficiency and mass resolution for Upsilons in Heavy Ion events and learn in the process Eventually, we would want to to improve

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Reconstructing Upsilons in di-muon channel in HI Events

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  1. Reconstructing Upsilons in di-muon channel in HI Events Sasha Lebedev and Marzia Rosati Iowa State University Immediate Goal:Study reconstruction efficiency and mass resolution for Upsilons in Heavy Ion events and learn in the process Eventually, we would want to to improve both efficiency and resolution by adjusting reconstruction parameters or writing new code Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 1

  2. Algorithm This analysis was done with 11.0.3 version. We are now moving to 11.5.0 Generate Single Upsilons (Pythia) Simulated PbPb Hijing Events Simulate Single Upsilons Merge Single Upsilons to simulated PbPb Hijing Events (PileUpEventLoopMgr) Digitize Single Upsilon Reconstruct Merged Events and produce ESD and AOD Reconstruct Single Upsilons and produce ESD and AOD Analyse ESD/AOD and produce AAN Analyse ESD/AOD and produce AAN Analyse ESD/AOD and produce AAN Compare Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 2

  3. Heavy Ion Specifics Reconstruction of even peripheral PbPb events takes forever with the default reconstruction settings (inner tracker too slow) doiPatRec = False doxKalman = True XKalMan.PrimaryVertexSearch = False XKaDetectorBuilder.TRT = False XKaMField.MagneticFieldService = 4 XKalMan.ReconstructionStrategy = 3 XKalMan.Selectivity = 9 XKalMan.MinNumberOfSilClusters = 9 XKalMan.MinNumberOfUniqueSilClusters = 2 XKalMan.Xi2forPrecisionClusters = 10. XKalMan.MaxNumberHoles = 11 - AOD production takes forever (MC truth?) Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 3

  4. Muon Reconstruction (1) Standalone Muon Reconstruction: Muonboy, MOORE Combined Muon Reconstruction: Staco, MuTag,MuonIDCombined, MuonIDStandAlone In our experience (with 11.0.3) only Muonboy and Staco results make sense for both singles and HI events. Available in Data Access Key C++ class ESD MuonboyTrackParticles TrackParticleContainer ESD StacoTrackParticles TrackParticleContainer AOD StacoMuonCollection MuonContainer AOD MuidMuonContainer MuonContainer Sasha Lebedev US ATLAS Muon Suftware Workshop 05/20/2006 4

  5. Muon Reconstruction (2) 1) Single Upsilons with -1 < h < 1 (h and PT distributions from pythia) Upsilons in pythia pp events with forced Upsilon production: 2) Full reconstruction (default settings) 3) HI settings (some stuff turned off or adjusted for HI events) HI events (PbPb @ 5.5 TeV): 4) Single Upsilons merged with b=6 Hijing events (HI settings) Each event was used several times with a different single Upsilon. Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 5

  6. Single Upsilons Generate single Upsilons decaying to muons, using Pythia. Pseudorapidity range: -1.0 to 1.0, all transverse momenta. Approximately half of all single Upsilons reconstructed in AOD (~46% Staco, ~51% MuID). Only ~1/4 of all single Upsilons are reconstructed in ESD ??? Problem: some muons are split in two Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 6

  7. Single Upsilons Mass in AOD (MuID) Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 7

  8. Single Upsilon Mass in ESD Staco efficiency relative to Muonboy ~ 70% Muonboy Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 8

  9. Merged HI Events Hijing was used to generate PbPb events @ 5.5 TeV. PileUpEventLoopMgr is used to merge Upsilons to PbPb events. This study uses b=6 Hijing events merged with single Upsilons and pp pythia events with forced Upsilon production. iPatRec turned off, tuned xKalman for HI events. Each Hijing event was used several times with different Upsilon events. Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 9

  10. Using MC Truth information (matchR) track matching parameter PT matching Using single Upsilons determine matching parameters and use them for merged Upsilon/HI events. dR < 0.004 abs(dPt) < 0.05 abs(dEta) < 0.003 h matching Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 10

  11. Upsilons merged to PbPb events with b=6 Staco efficiency relative to singles = 85% Muonboy efficiency relative to singles = 95% same sign combinatorial background Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 11

  12. Reconstruction Efficiency times Acceptance - Single HI Pythia Full Pythia HI Merged HI ESD Muonboy 16.3 +- 2% 18.6 +- 1% 18.6 +- 2% (95 +-3%) ESD Staco 11.3 +- 2% 16.9 +- 1% 15.7 +- 2% (85 +-3%) AOD Staco 32.8 +- 2% 25.1 +- 1% 25.0 +- 2% 0 AOD Muid 0 33.3 +- 1% 0 0 relative to singles Mass Resolution, MeV Single HI Pythia Full Pythia HI Merged HI ESD Muonboy 466 +- 64 580 +- 38 580 +- 38 656 +- 115 ESD Staco 167 +- 25 169 +- 12 198 +- 16 252 +- 70 AOD Staco 184 +- 16 139 +- 9 209 +- 15 N/A AOD Muid N/A 142 +- 9 N/A N/A Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 12

  13. Conclusions and Outlook Good news: - Event merging and reconstruction of HI events work - Upsilons are reconstructed with reasonably good efficiency and mass resolution in PbPb @ 5.5TeV events (b=6). Some Problems: - Muon track splitting (1-2%) - What happens in ESD-AOD transition? - AODs can not be produced for HI events - Reconstruction takes too much time (20-25 min per b=6 event) Plans for the future: - Learn more about muon reconstruction algorithms - More simulations, merging with more central events Sasha Lebedev US ATLAS Muon Software Workshop 05/20/2006 13

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