CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

Sebastian Fleischmann, Bergische Universität Wuppertal, GermanyTatjana Lenz, Bergische Universität Wuppertal, GermanyAndreas Salzburger, CERN PH-ATC & University of Innsbruck, AustriaAndreas Wildauer, CERN PH-ATC & University of Innsbruck, Austria

fast atlas tRack simulationnew

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

OutlineOutline

• ATLAS Detector and Tracking devices

• What’s behind Fatras - the new ATLAS offline Tracking software:

Extrapolation package, Reconstruction geometry

• Material budget + Material effects - comparison with full simulation geometry

• Fatras applications - validation of track fitters / pattern recognition

- track reconstruction dependency on magnetic field/material knowledge

• Outlook & Conclusion

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

Introduction: Introduction: ATLAS ExperimentATLAS Experiment

H 4 decay, Geant4

• Inner Detector Pixel Detector SCT Detector TRT Detector solenoidal field of ~ 2 Tesla

• Muon System MDT Chambers CSC Chambers RPC Chambers TGC Chambers compex toroidal field

• Calorimeter LAr Calorimeter Tile Calrimeter

Fatras

information: http://cern.ch/atlas

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

4-vector creation

SingleParticle, PYTHIA, HERWIG ...

Full/Fast Simulation/Track ReconstructionFull/Fast Simulation/Track Reconstruction

EVENT GENERATION

Full Detector Simulation interaction with detector material,

hit creation/particle decay

Geant4, FLUKA, …

Digitizationsingal + noise creation

Event Data Preparation

Track Finding

Track Fitting

Fast Detector Simulation

parametric smearingof track parameters according

to obtained smearingfunctions

EDM

EDM

ATLFAST

Analysis, Data Persistency, Event Visualization

Event Data Preparation

EDM

Trajectory CreationEDM

Track/Noise CreationEDM

Track Finding

Track Fitting

EDM

EDM

uses the Extrapolation Tooland Geometry of Reconstrucion

uses the Fitting/Data preparation Tools of Reconstrucion

Simulation

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

behindbehind

• the new fast track simulation is a spin-off of the development of the new ATLAS offline Tracking (i.e. track reconstruction) development: - very modular design (dedicated Tools and Algorithms) - dynamically loading of libraries (Interfaces) - configuration via python steering

• main component of Fatras is the newly developed track Extrapolation engine (with navigation)

• Fatras is using the reconstruction geometry as a simulation geometry (enhances navigation) • Fatras acts completely on the offline track reconstruction Event Data Model (EDM)

1 … n

Trajectory

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

Connective Geometry (TrackingGeometry)Connective Geometry (TrackingGeometry)

• the prediction of the trajectory is enhanced by the native navigation of the TrackingGeometry - between Volumes (via BoundarySurfaces) - between Layers (via interlinking)

• BoundarySurfaces and Layers extend the common Surface base class: - naturally used in Extrapolation • Volumes and Layers carry material information:

Layer based

Material interactions can be taken into account both ways.

Volume based

Navigation between Volumes:

Navigation between Layers:

Model of ATLAS SCT Detector

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

TrackingGeometry: TrackingGeometry: material budgetmaterial budget

Geant4

TrackingGeometry

Very complex fullDetector geometry~ 106 volumes in the ATLAS Inner Detector (ID)

Simplified reconstructiongeometry (TrackingGeometry)~ 50 volumes

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

number of hits/track number of hits/track

Fatras Fatras

offline Reconstructionoffline Reconstruction

Full simulated/reconstructed: 5000 mu tracks with 5 GeV Simulation: ~ 95 s/250 eventsDigitization: ~ 90 s/25 events

Fatras: 25000 tracks mu 5 GevSimulation/Refit: 95 s/5000 events

• Hits/track comparison: Fatras against Full sim./reco.

• First real-life Fatras test: tuning of reconstruction

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

applications: applications: validationvalidation

• Fatras was born as a VALIDATION tool, using same services (material, magnetic field, extrapolator) guarantees perfect controlled testbed:

- Track Fitters (initial intention) - Vertex Fitters - Pattern recognition

• Modular design of offline Tracking software automatically enhanced testbed for all fitters following a common ITrackFitter interface

• Fatras was used for strategy finding: - check EDM changes

slide by A. Franckowiak

(rrec – rhit)/r

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

applications: applications: magnetic field dep.magnetic field dep.

5000 tracks with 5 GeV simulated with realistic field (109.80 s, 2.0 GHz, including refit)

Refitted (KF) with 100% magnetic field Refitted (KF) with 98% magnetic fieldRefitted (KF) with 100% magnetic field Refitted (KF) with 98% magnetic field

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

applications: applications: Momentum scaleMomentum scale

5000 tracks with 5 GeV simulated with realistic field (av. 98.80 s/5000 events, 2.0 GHz, including refit)

Reconstruction ofsingle tracks using different scale factors for the reconstruction geometry:

Fine-Tuning of material budget in Reconstruction

Momentum scale estimation

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

applications: applications: More ?More ?

• Fatras does SingleTrackSimulation

- Pattern Recognition - Fitter Validation - Material Mapping

• Fatras does TracksFromVertexSimulation

- VertexFitter Validation

• Fatras does GenEventSimulation

- Vertexing - Pattern recognition - 2nd stage pattern search

CHEP06, Feb. 2006, Mumbai, India A. Salzburger, et. al.

ConclusionConclusion

• A new fast track simulation for the ATLAS Inner Detector has been deployed

• Spin-off of the new extrapolation package (simulation using the new reconstruction geometry)

• Enhanced by the modularity of the new ATLAS offline track reconstruction, completely written and embedded in the EDM

• Usage in validation of track finding and track/vertex fitting

• Powerful tool for fast checks / strategy finding

• Hasn’t reached it’s full power yet !