TRT LAr Tilecal MDT-RPC BOS Pixels&SCT 1 The Atlas combined testbeam Thijs Cornelissen, NIKHEF Jamboree, Nijmegen, December 2004

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 2 Introduction 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 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 Noemen: H8 Letertype Jargon!

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 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 P 4 Combined setup InnerDetector:  Pixels: 6 modules, inside magnet (B=1.4T)  SCT: 8 modules, also inside magnet  TRT: 1/16 th 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 P 5 Offline software flow Geant4 Hits G4 SimDigitization Raw Data Objects Simulation and Detector response Data Preparation PrepRawData (Clusters and Drift circles) and Space Points CTB Bytestream Track reconstruction Tracks 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!

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 6 Data taking Beams used: 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 P 7 Event display

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

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

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

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 11 SCT residuals after alignment Before alignmentAfter 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 P 12 TRT 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) Without calibration With calibration

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

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

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 15

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

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

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 20 calorimeter

Thijs Cornelissen - NIKHEF Jamboree, Dec 2004 P 21 Muons: Sagitta measurements 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 Sagitta definition at the TB: Sagitta Outer Middle Inner station

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

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

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