Atlas software developments

1. Atlas software developments Stan Bentvelsen

2. Layout • Atlas software status • Milestones • Frameworks • Building simulation • Geant4 validation • Detector Description • Reconstruction • Event definition • Track reconstruction • Preparations for physics • Analysis plans Preparations, preparations… NIKHEF Annual Meeting

3. Timeline towards start LHC 2001 2002 2003 2004 2005 2006 04 – Simulation: Geant4 validation 06 – Major migration to OO software (no Fortran!) 12 – Core software agreements complete 12 – Data Challence 0(‘continuity’ check) 06 – Physics readiness report 07 – Full chain real environment 12 – Full database infrastructure 04 – DC1 (large scale reconstruction & analysis) 08 – Computing TDR finished 12 – 10% processing farm 12 – 100 TB dBase prototype 01 – 40% processing farm 06 – LHC beam tunes 04 - LHC pilot run 06 - 100% processing farm 08 – LHC fist physics run 06 – Decide OS (linux?) 07 – DC2 (increased complexity) NIKHEF Annual Meeting

4. Reconstruction/analysis: Athena Gaudi Framework from LHCb Developed further by American groups (LBL) Keywords: Event store on which algorithms and services act Transient/persistency split Thoughtful design Simulation: FADS/Goofy Based on Geant 4 ‘event loop’ Developed by European / Japanese collaborators Keywords: Extremely lightweight Efficient Little default behavior Framework in Atlas schism Development of the C++ core software: Geant4 based Object Oriented Folly Objectivity / ASCII NIKHEF Annual Meeting

5. Geant 4 physics validation • Major milestone in ATLAS Simulation. • The goal of the validation is to increase trust in Geant4 simulation (as much as G3) such that it can be used for data production. • Collaboration projects with the Geant4 team. • ATLAS’ own internal activity. • Status of Geant4 similar to status of Geant3 before LEP started (around `85) • Geometry workable (one annoying bug) • Electromagnetic physics fine (upto % level) • Hadronic physics less well described NIKHEF Annual Meeting

6. Muon Detector • EM shower production by muons in absorber: extra hits in Muon Drift Tubes • Transverse distance of extra hits from muon track in Geant-4 broadly reproduces test beam data • Detailed agreement better for lighter absorber material NIKHEF Annual Meeting

7. Tile Calorimeter G4 G3 Geant3 vs data data 100 GeV Geant4 vs data 20 GeV Electrons Muons • No perfect match between G4 and test beam data NIKHEF Annual Meeting

8. FADS/Goofy robustness test • Geant4 simulation test (done before Xmas01) • 100 job-streams each of which processes 1,000 events Objectivity Database Objectivity Database Hits/ Hit-collections MCTruth FADS/Goofy Stream #001 HepMC H-> 4 leptons 1,000 events Hits/ Hit-collections MCTruth FADS/Goofy Stream #002 HepMC Pythia 6 1,000 events Hits/ Hit-collections MCTruth FADS/Goofy Stream #100 HepMC 1,000 events NIKHEF Annual Meeting

9. FADS/Goofy robustness test • Expected data size and CPU required per event 1,000 events 4-vectors database ~ 50 KB ~ 50 MB Hits/Hit-collections ~ 1.5 MB ~ 1.5 GB database CPU ~ 60 sec ~ 17 hours (Pentium III, 800MHz) • Required resources • PC farm ~ 10 CPUs ( 5 machines with dual processors) • Disk space ~ 155 GB • Process period ~ 1 week NIKHEF Annual Meeting

10. Detector Description framework Detector description scope Geometry description Materials Identifiers Conditional dBase Alignment Simulation Fast simulation Digitalization Visualization Reconstruction provider client NIKHEF Annual Meeting

11. Define geometry description for ATLAS in ascii format Use XML Unambiguous storage of numbers with their meaning Customized syntax Many free software tools Parsing, validating Widely accepted standard AGDD syntax Geometry dBase Logical description (Identifier) Material dBase E.g. geometry dBase contains Volumes Generic and descriptive Elementary solids Boolean solids Logical groupings of volumes Iteration Positioners Description of the instances of the volumes Absolute or relative, single or multiple Define the translation and rotation matrix wrt origin of the constituents Utilize symmetries DD of ideal static detector NIKHEF Annual Meeting

12. Example: XML implementation AGDD Header, version of DTD Section: sub-detector + author + version Section: detector, version, author Creation solid: tube Various positioning of volumes NIKHEF Annual Meeting

13. Problem with explicit description Many redundant numbers Allow for parametric description “Compactification” Specialized XML syntax Contain parameters as attributes Associated C++ algorithms to unpack Registration of algorithms to create transient objects AGDD.dtd Syntax def Compact AGDD XML ASCII file factory Generic AGDD XML ASCII file AGDD_Printer C++ Algorithms compact Generic Model Transient C++ ‘expanded’ Client programs Detector description AGDD: parametric description NIKHEF Annual Meeting

14. Build the Geant4 geometry from the information stored in XML ‘Generic’ translation Automatic translation; blind to the specific detector Need explicit description G4Builder ‘Detector specific’ translation Need algorithmic (compact) description Close connection to ATLAS simulation group AGDD syntax Syntax check Syntax check Compact description Explicit description Expand() Optimized code Automatic building Geant4 representation Geant4 representation Compare performance The Geant4 client NIKHEF Annual Meeting

15. SCT gallery NIKHEF Annual Meeting

16. Muon gallery NIKHEF Annual Meeting

17. Status AGDD in ATLAS • Work ongoing to create AGDD interface for all sub-detectors in ATLAS. • To agree among large community of people is not trivial! NIKHEF Annual Meeting

18. Simulation of the cosmic ray setup (at NIKHEF) Frank’s description of the geometry NIKHEF Annual Meeting

19. NIKHEF Annual Meeting

20. All materials Cosmic ray material-budget Aluminum MDT tubes • Standard tool (in G4Builder) • 3d scan in (eta-phi) of geantinos • Connection hits to digits available Radiation length Volume counter deg NIKHEF Annual Meeting

21. Common frame for SCT and PIXEL From hits to digits Surface charge Charged diodes Digits Detector element Local description of SCT strips Pixel diodes Modular design ‘Plug-in’ parameterizations Detailed versus fast simulation Digitization D Calvet NIKHEF Annual Meeting

22. Silicon wafer local description A Fornainii • Strips/pixels will not be separate volumes in G4 • Separate packages describing readout structure • segmentation into diodes • connection to readout electronics Pixel module Barrel strip module Endcap strip module NIKHEF Annual Meeting

23. Collection of digits Each collection connected to one ‘detector element’ Each digit connected to one ‘readout channel’ Detector-element description from XML Comparison to test beam data Threshold scan well described by the simulation Event model NIKHEF Annual Meeting

24. AMBER: first full OO tracking algorithm (P. Hendriks, 2000) COBRA: COmBined Reconstruction (W. Lavrijsen) Global generic track fitting using Track segment refit inner tracker and muon chambers Extrapolation and matching from track segments Global track refit Track reconstruction NIKHEF Annual Meeting

25. COBRA performs well COBRA vs IPATREC  COBRA vs MUONBOX Pt COBRA comparison • Comparable results for IPATREC • (inner tracker) • Comparable results for MUONBOX • (muon detector) NIKHEF Annual Meeting

26. Higgs reconstruction Golden channel at MH<400 GeV benefit from combined reconstruction inner muon comb (%) NIKHEF Annual Meeting

27. ATLAS physics at NIKHEF • Main themes of interest have been defined • Higgs, SUSY, Top, B-physics • NIKHEF staff will become active players in these fields • Develop NIKHEF toolkit, eg track reconstruction, jet definitions, front-end analysis. • PhD students: • Higgs -> 4 leptons (Lavrijsen, Peters, Woudstra) • SUSY (Buis) • Observation of Bc, production model (Scholte) • Bs mixing, CP violation (Fornaini) • Single top with polarization, Vtb and mass (Barisonzi) • Students in the group: • G. Lim, Y. Boer, F Jansen, B Dirks, J Dalhuizen NIKHEF Annual Meeting

28. Conclusions Big challenge to get the Atlas software ready at startup of LHC Middle of development • Transition to OO software paradigm • Detector description going • Geant4 toolkit validated. Atlas simulation underway. • Reconstruction/analysis chain getting up steam NIKHEF Annual Meeting