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The Atlas combined testbeam

The Atlas combined testbeam. Thijs Cornelissen, NIKHEF Jamboree, Nijmegen, December 2004. Introduction. Combined Testbeam: ~ March – November 2004 Full ATLAS barrel slice, starting from the interaction point (origin of the global coordinate system, same for all the detectors)

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The Atlas combined testbeam

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  1. The Atlas combined testbeam Thijs Cornelissen, NIKHEF Jamboree, Nijmegen, December 2004

  2. Introduction • Combined Testbeam: ~ March – November 2004 • Full ATLAS barrel slice, starting from the interaction point (origin of the global coordinate system, same for all the detectors) • All relevant sub-detectors participate • Detectors in their real positions as in ATLAS • Primary objectives & motivations: • Combined data taking with all the detectors • Testing of the whole Dataflow system (common LVL1 trigger, EF, ATLAS Event Format, etc.) • Final prototypes of the electronics (RODs) • Combined calorimetry studies • Combined studies of the InnerDetector • Combined studies ID + Muons Noemen: H8 Letertype Jargon! Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  3. InnerDetector: • Pixels: 6 modules, inside magnet (B=1.4T) • SCT: 8 modules, also inside magnet • TRT: 1/16th of the barrel Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  4. Combined setup • InnerDetector: • Pixels: 6 modules, inside magnet (B=1.4T) • SCT: 8 modules, also inside magnet • TRT: 1/16th of the barrel • Calorimetry: • LAr: barrel module 0 + cryostat • TileCal: 3 layers of modules • Muon detectors: • 1 barrel projective tower (MDTs + RPCs) • 1 endcap sector (MDTs+TGCs) Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  5. Offline software flow Simulation and Detector response Geant4 Hits Data Preparation G4 Sim Digitization PrepRawData (Clusters and Drift circles) and Space Points Raw Data Objects Bytestream CTB • The full ATLAS offline software is used for the testbeam data. Excellent test for various components: • Bytestream converters • Calibration and alignment • Track reconstruction • Some testbeam-specific solutions were inevitable, but still, many bugs solved already that would otherwise have appeared in 2007! Track reconstruction Tracks Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  6. Data taking • Beams used: 1-180 GeV pion/electrons/photons A complete vertical slice of ATLAS is available and we can exploit the full power of the ATLAS detector for detailed particle id and measurement Situation where many detector communities interact, and have to work together towards a common physics aim Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  7. Event display Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  8. Event display Welke bundel Welke software Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  9. Event display Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  10. Some events are more difficult  Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  11. SCT residuals after alignment Before alignment After alignment • After alignment, the average residual over all the planes is found to be 25 micron (again close to expected). Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  12. TRT calibration With calibration Without calibration • The TRT hits are represented by vertical lines. The top and bottom of the line are the edges of the driftcircle, so that’s where the track should be. • Without calibration, Athena was assuming t0 = 0 for all the straws, while in reality it is more like 25 ns. As a result, the residuals are about 1 mm. • Calibration clearly improves things. If the straw is not found in the map of calibrated straws then the average of all the straws is applied (still much better than the Athena default) Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  13. Curved tracks with helix fitter Run 2102130, 9 GeV pions, B=1.4 T Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  14. Curved tracks with helix fitter Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  15. Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  16. Ganged pixels • The particle hits almost the same spot in each of the modules it hits. So often you get ganged pixels in three layers at the same time. • Probably need detailed alignment to solve this reliably, these hits are ignored for now in the SL fitter. Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  17. Momentum reco with xKalman Run 2102130, 9 GeV pions, B = 1.4 T Alleen pixel en sct Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  18. Inner detectgor: conclusions • Wat hebben we bereikt tot nog toe? • Wat moeten we nog doen? • Aligniering • Calibratie • Conditions: noise levels + dead channels • efficiency • Algemene performance Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  19. Calorimetry: LAr-Tile correlation e p Quasi-online monitoring inside Athena Tile and LAr not calibrated Muons removed with Muon-tag m Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  20. calorimeter Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  21. Outer Middle Sagitta Muons: Sagitta measurements Sagitta definition at the TB: • Create r-z and phi track-segments, perform pattern recognition • Segments fit on each muon station • Combination of inner and outer,compare with middle station • Misalignment affects mean value and width • Multiple scattering affects width Innerstation Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  22. G4 G4 Data Data Athena 8.7.0 Athena 8.8.0 RPC internal structure DED Comparisons with G4 simulation Sagitta width Sagitta width After fixing the problem - Difference G4-Data  1/p: material problem(effect corresponding to ~3 cm aluminumequivalent). - Detailed check of materials associated to GeoModel volumes-problem was found in RPC Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  23. ID-Muon Track Correlation ID ID ID Muons Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

  24. Conclusions • Was het een leuke/leerzame testbeam periode? • Testbeam volgend jaar? • Zijn we nu helemaal voorbereid op het nemen van data bij Atlas? Thijs Cornelissen - NIKHEF Jamboree, Dec 2004

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