Download - The Atlas combined testbeam
TRTLAr
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The Atlas combined testbeam
Thijs Cornelissen,NIKHEF Jamboree,Nijmegen, December 2004
Thijs Cornelissen - NIKHEF Jamboree, Dec 2004
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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: H8LetertypeJargon!
Thijs Cornelissen - NIKHEF Jamboree, Dec 2004
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InnerDetector:Pixels: 6 modules, inside magnet (B=1.4T)SCT: 8 modules, also inside magnetTRT: 1/16th of the barrel
Thijs Cornelissen - NIKHEF Jamboree, Dec 2004
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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
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Offline software flow
Geant4 Hits
G4 Sim Digitization
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
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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
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Event display
Thijs Cornelissen - NIKHEF Jamboree, Dec 2004
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Event display
Welke bundelWelke software
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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 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
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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
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Curved tracks with helix fitterRun 2102130, 9 GeV pions,
B=1.4 T
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Curved tracks with helix fitter
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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 2102130, 9 GeV pions, B = 1.4 T
Alleen pixel en sct
Thijs Cornelissen - NIKHEF Jamboree, Dec 2004
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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 19Calorimetry: LAr-Tile correlation
e
Quasi-online monitoring inside Athena
Tile and LAr not calibrated
Muons removed with Muon-tag
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calorimeter
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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
Innerstation
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Comparisons with G4 simulation
G4Data
Athena 8.7.0
DataG4
Athena 8.8.0
- 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
DED
RPC internal structure
After fixing the problem
Sagitta width Sagitta width
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IDID
ID-Muon Track Correlation
IDMuons
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Conclusions
Was het een leuke/leerzame testbeam periode? Testbeam volgend jaar? Zijn we nu helemaal voorbereid op het nemen van data bij
Atlas?