the atlas combined testbeam

TRTLAr

Tilecal

MDT-RPC BOS

Pixels&SCT

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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!


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InnerDetector:Pixels: 6 modules, inside magnet (B=1.4T)SCT: 8 modules, also inside magnetTRT: 1/16th of the barrel


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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)


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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!


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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


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Event display


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Event display

Welke bundelWelke software


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Event display


P 10 Some events are more difficult


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).


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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


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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.


P 17 Momentum reco with xKalman

Run 2102130, 9 GeV pions, B = 1.4 T

Alleen pixel en sct


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


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


P 22

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?

the atlas combined testbeam

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