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31.05.2005

Flash Tracking / Vertexing. 31.05.2005. SOFTWARE - tracking - vertexing - alignment FLASH Algorithms - needed by numerically intensive alignment - and by LVL-2 Trigger time constraints. 31.05.2005. ATLAS Trigger - architecture - general event and Pixel Detector - CPU demand

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31.05.2005

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  1. Flash Tracking / Vertexing 31.05.2005

  2. SOFTWARE - tracking - vertexing - alignment • FLASH Algorithms - needed by numerically intensive alignment - and by LVL-2 Trigger time constraints 31.05.2005

  3. ATLAS Trigger - architecture - general event and Pixel Detector - CPU demand • LIN / HLX Fit - 2Dxy and 2Drz flash fit - Rcurvature / pt / bimpact - 3Dhelix flash fit (zhypothesis test) - Bcone test • VTX Fit - LIN fit and HLX fit - KIN fit • TRK-ing - axial and azimuthal confinement - performance 31.05.2005

  4. INPUT to LVL2 B-Physics 100-200 Hz ATLASTrigger Architecture 31.05.2005

  5. H  bb event 22 min. bias events H  bb event @ high luminosity Pixel Detector, 3 layers Event Occupancy ... and Pixel Detector 31.05.2005

  6. DOCA ... expansion HLX Mathematics Bcone 31.05.2005

  7.  det / tr2 , where MATRIX = < r r > - < r > < r > 2Dxy Flash Fit .... • xy - determine: waist / length = • validate - combinations that not completely off-the-wall 31.05.2005

  8. 2Drz Flash Fit .... • rz - similar to xy-validation • param.‘s - fit plane = 0z x „r“ - as det. from xy-fit • validate - combinations that not completely off-the-wall 31.05.2005

  9. find Rcurvature pt • find bimpact • in/validate acc.-ly Pt and bimpact Magic Formula Nr. 7 31.05.2005

  10. 3DHLX Flash Fit Magic Formula Nr. 9 • xy acc.-y z acc.-y • angle assgn.‘s = given by xy fit • TEST if z‘s „line-up“ at xy-pred. pace ! ... (helical step) • in/validate acc.-ly 31.05.2005

  11. Magic Formula Nr. 8 determinant in how much info can be extracted Bcone Test IF good dip-angle ...  • chance to probe CONE-angle of trk. within Bdecay cone • use ... • in/validate acc.-ly 31.05.2005

  12. HLX Fit Routine ATHLON XP1600+ Conclusions 31.05.2005

  13. LIN VTX-ing - LIN trk.‘s • vtx cond. = closest approach to all trk.‘s • result ... 31.05.2005

  14. Not bad !... LIN VTX-ing LIN extrapolation ... • at DOCA • assume all trk.‘s LIN • do FLASH vtx-fit • PROBLEM is ... det. resolution effects 31.05.2005

  15. LIN VTX-ing EXAMPLE ...  • RESOLUTION worsens with thinning of Bcone of decay ! 31.05.2005

  16. Not yet ! ATHLON XP1600+ CPU vs. nr. of tracks 31.05.2005

  17. ... 20% more CPU HLX VTX-ing Consciencious decision • implement some OIIcorrections ! (fewer events) (fewer events) 31.05.2005

  18. KIN Fit .... • HELIX - determine gyration center for trk. w/ 4 points < r r > - < r > < r > = (< r r > - < r > < r>) XC - re-do all previous HLX fit steps • VERTEX - re-fit w/ new trk. param.‘s 2 2 31.05.2005

  19. Conclusions 31.05.2005

  20. TRK-ing • preliminary cuts - jet-IP - axial confinement - azimuthal confinement • use HLX fit - reject poor intermediate results - get trk par.‘s - Bcone test • parametrise - nr. ghosts / event - efficiency - speed 31.05.2005

  21. constant factor (for given trk) Simple jet-IP determination: Axial Confinement Requirements ... • trk. from yellow area 31.05.2005

  22. Azimuth: wrt gyr.-center Selection criterion: absolute Azimuthal Confinement Requirements ... • pt > 1 GeV/c  Rmin • trk. from yellow area  r 31.05.2005

  23. Results • rejection - ROI 245:1 - axial confinement not yet implemented - azimuthal confinement 95:1 - HLX routine 420:1 • timing on ATHLON XP1600+ - 5 ms / ROI - multi-hadronic event • parameters - only HLX (flash routines !) - nr. ghosts / event - efficiency - speed 31.05.2005

  24. Multi-track alignment H8 Beam Tests, SPS • 180 GeV pions • strips (50 m dist.) Resolution of Pixels 31.05.2005

  25. Lorentz SHIFTS • “focal plane” for B = 0 • rotate to XY coord.’s Trigger Diode Image • image “shift” for B  0 • use edges ! • DIRECT determination of Lorentz shifts ! 31.05.2005

  26. ! hot-swaps ATHENA Framework - IRIS stalk • efficient code-devel. ! • shared dev.-to-dev. resources • easy code comparisons • simple 31.05.2005

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