1. ATLAS Simulation/Reconstruction Software Reported by S. Rajagopalan work done by most US Institutes. U.S. ATLAS PCAP review Lawrence Berkeley National Laboratory January 15, 2002

2. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 2 Outline  Simulation/Reconstruction Activities: (mostly by physicists)  Subsystems with US participation: Pixels, TRT, EM Cal, Forwad Cal, Tile Cal, Muons, Trigger  In addition, extensive participation in combined reconstruction, test beam software and physics analysis.  Well integrated into overall ATLAS computing effort.  In particular, the US core efforts on Athena and DB.

3. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 3 ATLAS Subsystem/Task Matrix  US responsibles  Being vacated Offline Coordinator ReconstructionSimulationDatabaseChair N. McCubbin D. Rousseau A. Dell’Acqua D. Malon Inner Detector D. Barberis D. Rousseau F. Luehring S. Bentvelsen / D. Calvet Liquid Argon J. Collot S. Rajagopalan M. Leltchouk H. Ma Tile Calorimeter A. Solodkov F. Merritt V.Tsulaya T. LeCompte MuonJ.Shank J.F. Laporte A. Rimoldi S. Goldfarb LVL 2 Trigger/ Trigger DAQ S. George S. Tapprogge M. Weilers A. Amorim / F. Touchard Event Filter V. Vercesi F. Touchard

4. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 4 Software Activities Summary  Recent simulation and reconstruction activities have been geared toward:  High Level Trigger (HLT) Technical Design Report (due summer 2003)  G4 physics validation  Validation of C++ reconstruction software  Data Challenges (DC1 ongoing)  Test beam analysis  Physics studies by various groups

5. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 5 Geant3 simulation software  P. Nevski (BNL) is the ATLAS coordinator for the G3 effort.  Recent Activities include:  First revision of geometry since Physics TDR Latest geometry of the Inner Detector (incertable pixels, 2/3 layer variation, strip tilt inverted to minimize cluster size, realistic R/T in TRT) Service Material updated Calorimeter: gap between barrel and endcap calorimeters introduced readout of calorimeters updated (including 5 sample digitization) dead material of the calorimeter readout updated Muon layout modified to latest geometry, digitization updated Optimised pile-up procedure allowing up to > 1k events to be added

6. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 6 G4 Simulation activities (Pixel)  Pixel Simulation (D. Costanzo et. al., LBNL)  Pixel Geometry: Primary numbers from MySQL database  (used also by Geant3)  Geometry descriptions in GeoModel MisAlignments handled by new Athena Services

7. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 7 Material (Pixel) in G4

8. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 8 TRT Simulation  F. Luehring (Indiana) is the ATLAS TRT software coordinator.  (and member of the TRT steering group)  Athena Pile-Up Requirements documentation ATL-SOFT-2001  GEANT4 code writing  TRT hit and digitization definitions  Tabulation of material in the TRT detector  And its appropriate include in G4 simulation  Studies of effect of Pile-up in TRT detector

9. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 9 LAr Simulation  ATLAS LAr simulation coordination: M. Leltchouk (Nevis)  Participation in G4 EM barrel development  Integration of the LAr Simulation code in G4 architectured by Bill Seligman : Used as templated by EM, HEC, FCAL.  LAr EM calorimeter hits (LArEMHit) were implemented in GEANT4 by B.Seligman.  Integrated with Athena Framework providing Root based persistency to G4 Hits and using them for subsequent Digitization/Reconstruction

10. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 10 GEANT 4 LAr Simulation

11. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 11 G4 Validation compare features of interaction models with similar features in the old Geant3.21 baseline try to understand differences in applied models, like the effect of cuts on simulation parameters in the different variable space (range cut vs energy threshold…); try to understand differences in applied models, like the effect of cuts on simulation parameters in the different variable space (range cut vs energy threshold…); use available experimental references from testbeams for various sub-detectors and particle types to determine prediction power of models in Geant4 (and Geant3); use available experimental references from testbeams for various sub-detectors and particle types to determine prediction power of models in Geant4 (and Geant3); use different sensitivities of sub-detectors (energy loss, track multiplicities, shower shapes…) to estimate Geant4 performance; use different sensitivities of sub-detectors (energy loss, track multiplicities, shower shapes…) to estimate Geant4 performance; tune Geant4 models (“physics lists”) and parameters (range cut) for optimal representation of the experimental detector signal with ALL relevant repects; tune Geant4 models (“physics lists”) and parameters (range cut) for optimal representation of the experimental detector signal with ALL relevant repects;

12. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 12 G4 validation comparisons Muon energy loss and secondaries production in the ATLAS calorimeters and muon detectors Electromagnetic shower simulations in calorimeters Electromagnetic shower simulations in calorimeters Hadronic interactions in tracking devices and calorimeters Hadronic interactions in tracking devices and calorimeters (Different showering models in Geant3 and Geant4) Reconstructed Energy [GeV] 0.10.20.30.40.50.60.70.80.91 0 -3.5 -3.0 -2.5 -2.0 -1.5 -0.5 Reconstructed Energy [GeV] Δ events/0.1 GeV [%] Fraction events/0.1 GeV 10 -4 10 -3 10 -2 10 -1 0.10.20.30.40.50.60.70.80.91 E μ = 100 GeV, η μ ≈ 0.975

13. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 13 G4 Validation (continued) Geant4 can simulate relevant features of muon, electron and pion signals in various ATLAS detectors, often better than Geant3; Remaining discrepancies, especially for hadrons, are being addressed and progress can be expected in the near future; Remaining discrepancies, especially for hadrons, are being addressed and progress can be expected in the near future; ATLAS can has a huge amount of the right testbeam data for the calorimeters, inner detector modules, and the muon detectors to evaluate the Geant4 physics models in detail; ATLAS can has a huge amount of the right testbeam data for the calorimeters, inner detector modules, and the muon detectors to evaluate the Geant4 physics models in detail; feedback loops to Geant4 team are for most systems established since quite some time; communication is not a problem; feedback loops to Geant4 team are for most systems established since quite some time; communication is not a problem; Few people in US involved in G4 validation studies I don’t think anyone from US is a member of the G4 team

14. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 14 Sub-System Reconstruction  Extensive involvement by US people, primarily in:  LAr, Tile and Muon reconstruction  Combined reconstruction: egamma, Jets, tau’s and MissingET  The overall reconstruction chain is functional, a lot of the fortran code has been rewritten in C++, albeit several missing pieces and far from perfect.  Most of the effort is focussed on:  Validation  Calibration issues  Test Beam Analysis  Standardizing the EDM and Detector Description usage

15. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 15 Database/Detector Description  Support for ROOT persistency for current Detector Description & some Event Data Objects (Hong Ma, BNL who also coordinates ATLAS LAr database activities)  LAr Database/Detector Description activities  Designed interfaces for accessing conditions data in Athena. Implemented interim solution for conditions data in MySQL for MC simulation, reconstruction, and some testbeam analysis.  Provide requirements input to ATLAS Conditions DB development  Detector Description: 2-day workshop at BNL (12/16/02) to discuss the adoption of the new Detector Description Architecture in LAr Simu/Rec.  Tile Database activities coordinated by Tom Lecompte (ANL)  Similar activities as those for LAr.  Muon database and detector description XML detector description: MDTs, RPCs, TGCs implemented Identifier scheme for Muons implemented by Goldfarb, Assamagan

16. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 16 Calorimeter Reconstruction  Liquid Argon : H. Ma, S. Rajagopalan (BNL), P. Loch (Arizona)  Tile Calorimeter : A. Gupta, F. Merritt (Chicago)  Combined Calorimeter Data Classes and Algorithms SimulationOnlineOfflineReconstructionCombinedReconstruction LArHit LArDigit LArRaw CaloCell CaloTower CaloCluster TileHit TileDigit TileRaw SimpleTrack egamma ProtoJet/Jet tauObject MissingET

17. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 17 1MB at t=0 + 25 bunch crossings with 10 interactions each (E not corrected for sampling fraction) Expected elec. noise reduction from optimal filtering Pile up increase (note: OF coeff used are the same In real life, they will change with luminosity Middle Sampling EM Barrel

18. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 18 Recent Plots using LAr recon. program

19. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 19 ATLAS Muon Software  J. Shank (Boston U.) is the overall software coordinator  Muon Database activities coordinated by S. Goldfarb (Michigan)  Current activity:  OO muon reconstruction (Moore) development Contributors: G. Stavropolous (LBNL), K. Assamagan (BNL) Integrated into Athena; in repository; in early development Migration to new Event Data Model Clusterization for MDT and CSC completed Makes use of common track fitting and data classes with InDet Reco Material Integration Service being implemented  Muon database and detector description Conditiond DB and Athena Testbeam work for the April run. J. Rothberg (U. Wash) Identifers & detector description by Goldfarb, Assamagan

20. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 20 ATLAS Muon Database Contributions Descriptions of Barrel Toroid (left) and H8 test beam geometry (below). Both geometries were generated using compact AGDD syntax and both were developed by REU summer students, under the supervision of S. Goldfarb.

21. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 21 Raw Data Flow  Raw Data Flow Model established  London Meeting: (D.Quarrie & S. Rajagopalan met with HLT to discuss their software design)  Established strategy on use of Athena/StoreGate in HLT  Data Converters (Hong Ma, BNL):  Simulation of ROB data and establishing relevant services  ByteStream  Raw Data and Calibrated Objects for use in L2, L3 coordinated across all sub-systems by Hong Ma (and implemented for Liquid Argon)  Being implemented for Muons (K. Assamagan, BNL)  Efficient on demand access to data in Regions of Interest

22. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 22 Simulation Data Flow GeneratorMcTruth(Gen)HepMC ROD Emulation Algorithm L1 Digitization Particle FilterSimulation PileUp McTruth(Sim)Hits ROD Input Digits McTruth(PileUp) DigitizationRawDataObjects ByteStream ConversionSvc MergedHits L1Digits L2Result EFResult L1 Emulation (inc. L1 ROD) L1Result ROD Emulation (passthru) L2 Selection Algorithm EF Selection Algorithm ByteStream Uses RawDataObjects ATLAS

23. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 23 Validation of Athena for HLT Use  The ATLAS EF will use selection and classification algorithms derived from the offline suite  Offline software performance therefore has a direct impact on EF farm size and cost  The HLT community has started “validation studies” (detailed benchmarking) of Athena, offline algorithms, and event model  The aim is to set metrics for monitoring trends in software performance  It is clear that the software is presently far from adequate  Not fair to judge during development phase  But benchmarking can (and has) helped spur improvements  Feedback during monthly meetings with A-team and regular interactions with developers  Software performance is also important for offline – hope that offline community will continue this work

24. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 24 Combined Reconstruction  egamma Reconstruction  Algorithms developed by H. Ma, S. Rajagopalan (BNL)  Algorithms to associate clusters and tracks and analyze variables necessary for e  identification (shower shapes, isolation, E/p, …)  Calorimeter Cluster calibration (J. McDonald, Pittsburgh)  Jet Reconstruction  Jet Algorithms (KT and cone) developed by A. Gupta, F. Merritt (Chicago)  Jet and Tau Calibration (F. Paige, H. Ma, S. Rajagopalan) (BNL) H1 style calibration adopted : Provides weighting at a cell level. EM showers are denser than hadronic showers: Cells with dense energy deposition are weighted toward EM scale. Effective in improving linearity and resolution over standard techniques (sampling weights).  Missing ET Reconstruction

25. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 25 Physics validation  DC1 data production includes datasets from single electrons, pions, di-jet events to full physics events with & without pile-up using G3.  Much of this data is already being analyzed to extract the relevant calibration constants that is fed back into the process for full reconstruction.  One of the physics signatures fully simulated is 50k SUSY events at the following msugra point : (I. Hinchliffe, F. Paige driving this effort) m 0 =100, m 1/2 =300, A 0 =-300, tan  =6, sign(  ) = +  Rich in leptons (including tau’s), jets, b-jets, high multiplicity hard events which is an ideal candidate to test the software.  Most such signatures have previously been studied only with fast simulation

26. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 26 e/Jet identification in SUSY events First look at 500 events from the SUSY sample : First look at 500 events from the SUSY sample :

27. PCAP review. January 15, 2003 S. Rajagopalan ATLAS Simulation & Reconstruction Software 27 Summary  New ATLAS framework, Athena, enthusiastically embraced by broad spectrum of sub-system community.  Many US physicists active in code development  Well integrated into overall ATLAS software effort  Schedule:  DC 0 12/2001 First phase which provided a useful software continuity check  DC 1 02/2002 Large scale simulation/reconstruction with G3.  Phase 1 ongoing, Phase 2 due in March 2003.  Athens Physics Workshop (May 2003)  DC2 : Will use Geant4, Scheduled for early 2004