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LCD Full Simulation & Reconstruction

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  1. LCD Full Simulation & Reconstruction Norman Graf (SLAC) Chicago January 7, 2002

  2. Linear Collider Environment • Detectors designed to exploit the physics discovery potential of e+e- collisions at s ~ 1TeV. • Will perform precision measurements of complex final states. • Require: • Exceptional momentum resolution • Excellent vertexing capabilities • “Energy Flow” calorimetry • Hermeticity Norman Graf

  3. Mission Statement • Provide full simulation capabilities for Linear Collider physics program: • Physics simulations • Detector designs • Reconstruction and analysis • Need flexibility for: • New detector geometries/technologies • Different reconstruction algorithms • Detector R&D, testbeams, … Norman Graf

  4. International Cooperation • Limited resources demand efficient solutions, focused effort. • As experimentalists, we can remain agnostic about the source of the data. • Technology and siting of the accelerator ~unimportant to the physics. • At best, one collider will be realized. • World LC community will coalesce. • Best to do so earlier, rather than later. Norman Graf

  5. Recent Focus • Efforts devoted to providing physics analysis package for Snowmass meeting. • Emphasis on integrated environment for event generation and fast detector simulation. • Provided CD-ROM with precompiled executables (Windows and Linux), API, tutorials and example code. • Less work on full reconstruction. Norman Graf

  6. Plans • Concentrate on GEANT4 full detector simulation. • Emphasize results from full reconstruction. • Full pattern recognition. • “Energy Flow” jet reconstruction. • Ab initio particle ID • Include machine backgrounds. • Iterate detector design based on above. Norman Graf

  7. GEANT 4 • We have begun the transition to GEANT4 by incorporating the existing XML geometry-parsing code. • Have defined generic hit classes for sensitive tracker and calorimeter hits. • Latest parser (xerces) supports XML Schema. Very useful for “compile-time” type safety and bounds checking. • Prefer a common G4 XML-based solution. Norman Graf

  8. Towards Internationalization • Suggest that Tesla, NLC and JLC full simulation groups could run a single GEANT4 executable. • Geometry determined at run-time (XML). • Write out common “ideal” hits (~flat-file). • Digitize as appropriate with plug-ins. • Enormous savings in effort. • Makes comparisons easy. • Prefer common GEANT4 solution. Norman Graf

  9. Full Simulations BRAHMS GEANT3 FORTRAN LCD Full Sim GISMO C++ JIM GEANT3 FORTRAN Common GEANT4 executable XML-based geometry Generic Hit output Norman Graf

  10. Analysis Frameworks • Inclusive environment; support both ROOT/C++ and JAS/Java frameworks. • Jet-Finding algorithms, invariant mass calculations, vertexing (based on SLD ZVTOP), flavor tagging, etc. are all available. • Displays for event visualization. • Histograms, fitting, etc. Norman Graf

  11. LCDROOT Event Display Norman Graf

  12. JAS 2D LCD Event Display Norman Graf

  13. Wired LCD Event Display Norman Graf

  14. bBD cD D D B primary primary Topological Vertex Finder • SLD’s unique topological vertex finder + mass tag D.J.Jackson NIM A388, 247 (1997) SLD collaboration PRL 80, 660 (1998) Norman Graf

  15. Vertex Mass and Charge Norman Graf

  16. Norman Graf

  17. Encourage participation • Tools are in place for many analyses. • Time may be right for a mock data challenge. • Will stress current reconstruction, but spurs creativity. • Upcoming Meetings • ECFA/DESY Meeting, St. Malo, April. • N. American meeting May/June? • ACFA meeting, Tokyo, July. • LCWS 2002 Jeju Island, August. Norman Graf

  18. Data Generation and Analysis • Generate MC events with full complement of backgrounds. • Include beam structure, overlap events. • Include machine backgrounds. • Write out only detector hits; no MC info. • Force development of reconstruction algorithms. • Uncover “signal”. Norman Graf

  19. Data Analysis Engine User’s Java Code DATA Padded Cell JAS Remote Data Access GUI Experiment Extensions (Event Display) Java Compiler + Debugger Norman Graf

  20. Distributed Analysis Server Server Server Control Server Catalog Server Client Norman Graf

  21. Summary • The LCD group has developed a very dynamic detector design, data reconstruction and physics analysis simulation environment. • This talk has only scratched the surface on a large body of work conducted by a remarkably small community of dedicated individuals. • Much work remains to be done and we could all benefit from collaborative effort. • Need to get serious about detector design based on realistic backgrounds and analysis. Norman Graf

  22. URL • American Linear Collider Detector simulation efforts are documented at: www-sldnt.slac.stanford.edu/nld • Binaries, full source, API, tutorials, etc. • Thanks to: A. Johnson, G. Bower, R. Cassell, T. Abe, M. Iwasaki, W. Walkowiak, M. Ronan, B. Schumm, et al. • Mail to: Norman.Graf@slac.stanford.edu Norman Graf