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ATLAS Simulation/Reconstruction Software
Reported by S. Rajagopalan Reported by S. Rajagopalan
work done by most US Institutes.work done by most US Institutes.
U.S. ATLAS PCAP reviewU.S. ATLAS PCAP review
Lawrence Berkeley National LaboratoryLawrence Berkeley National Laboratory
January 15, 2002January 15, 2002
PCAP review. January 15, 2003PCAP review. January 15, 2003S. Rajagopalan ATLAS Simulation & Reconstruction SoftwareS. Rajagopalan ATLAS Simulation & Reconstruction Software 2
Outline
Simulation/Reconstruction Activities:Simulation/Reconstruction Activities:(mostly by physicists)
Subsystems with US participation:
Pixels, TRT, EM Cal, Forwad Cal, Tile Cal, Muons, Trigger
In addition, extensive participation in combined reconstruction, test
beam software and physics analysis.
Well integrated into overall ATLAS computing effort.Well integrated into overall ATLAS computing effort. In particular, the US core efforts on Athena and DB.
PCAP review. January 15, 2003PCAP review. January 15, 2003S. Rajagopalan ATLAS Simulation & Reconstruction SoftwareS. Rajagopalan ATLAS Simulation & Reconstruction Software 3
ATLAS Subsystem/Task Matrix
US responsiblesUS responsibles
Being vacatedBeing vacated
Offline Offline CoordinatorCoordinator
ReconstructionReconstruction SimulationSimulation DatabaseDatabase
ChairChair N. McCubbinN. McCubbin D. RousseauD. Rousseau A. Dell’AcquaA. Dell’Acqua D. MalonD. Malon
Inner DetectorInner Detector D. BarberisD. Barberis D. RousseauD. Rousseau F. LuehringF. Luehring S. Bentvelsen /S. Bentvelsen /D. CalvetD. Calvet
Liquid ArgonLiquid Argon J. CollotJ. Collot S. RajagopalanS. Rajagopalan M. LeltchoukM. Leltchouk H. MaH. Ma
Tile CalorimeterTile Calorimeter A. SolodkovA. Solodkov F. MerrittF. Merritt V.TsulayaV.Tsulaya T. LeCompteT. LeCompte
MuonMuon J.ShankJ.Shank J.F. LaporteJ.F. Laporte A. RimoldiA. Rimoldi S. GoldfarbS. Goldfarb
LVL 2 Trigger/ LVL 2 Trigger/ Trigger DAQTrigger DAQ
S. GeorgeS. George S. TapproggeS. Tapprogge M. WeilersM. Weilers A. Amorim /A. Amorim /F. TouchardF. Touchard
Event FilterEvent Filter V. VercesiV. Vercesi F. TouchardF. Touchard
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Software Activities Summary
Recent simulation and reconstruction activities have been geared Recent simulation and reconstruction activities have been geared
toward:toward:
High Level Trigger (HLT) Technical Design Report (due summer 2003)
G4 physics validation
Validation of C++ reconstruction software
Data Challenges (DC1 ongoing)
Test beam analysis
Physics studies by various groups
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Geant3 simulation software
P. Nevski (BNL) is the ATLAS coordinator for the G3 effort.P. Nevski (BNL) is the ATLAS coordinator for the G3 effort.
Recent Activities include:Recent Activities include:
First revision of geometry since Physics TDR Latest geometry of the Inner Detector (incertable pixels, 2/3
layer variation, strip tilt inverted to minimize cluster size, realistic R/T in TRT)
Service Material updated Calorimeter: gap between barrel and endcap calorimeters
introduced readout of calorimeters updated (including 5 sample
digitization) dead material of the calorimeter readout updated Muon layout modified to latest geometry, digitization updated Optimised pile-up procedure allowing up to > 1k events to be
added
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G4 Simulation activities (Pixel)
Pixel Simulation (D. Costanzo et. al., LBNL)Pixel Simulation (D. Costanzo et. al., LBNL) Pixel Geometry: Primary numbers from MySQL database
(used also by Geant3)
Geometry descriptions in GeoModel MisAlignments handled by new Athena Services
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Material (Pixel) in G4
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TRT Simulation
F. Luehring (Indiana) is the ATLAS TRT software coordinator.F. Luehring (Indiana) is the ATLAS TRT software coordinator. (and member of the TRT steering group)
Athena Pile-Up Requirements documentation ATL-SOFT-2001Athena Pile-Up Requirements documentation ATL-SOFT-2001
GEANT4 code writingGEANT4 code writing TRT hit and digitization definitions
Tabulation of material in the TRT detectorTabulation of material in the TRT detector And its appropriate include in G4 simulation
Studies of effect of Pile-up in TRT detectorStudies of effect of Pile-up in TRT detector
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LAr Simulation
ATLAS LAr simulation coordination: M. Leltchouk (Nevis)ATLAS LAr simulation coordination: M. Leltchouk (Nevis)
Participation in G4 EM barrel developmentParticipation in G4 EM barrel development Integration of the LAr Simulation code in G4 architectured by Bill
Seligman : Used as templated by EM, HEC, FCAL.
LAr EM calorimeter hits (LArEMHit) were implemented in GEANT4
by B.Seligman.
Integrated with Athena Framework providing Root based persistency
to G4 Hits and using them for subsequent
Digitization/Reconstruction
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GEANT 4 LAr Simulation
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G4 Validation
compare features of interaction models with similar features in compare features of interaction models with similar features in the old Geant3.21 baselinethe old Geant3.21 baseline
try to understand differences in applied models, like the try to understand differences in applied models, like the effect of cuts on simulation parameters in the different effect of cuts on simulation parameters in the different variable space (range cut vs energy threshold…);variable space (range cut vs energy threshold…);
use available experimental references from testbeams for use available experimental references from testbeams for various sub-detectors and particle types to determine various sub-detectors and particle types to determine prediction power of models in Geant4 (and Geant3);prediction power of models in Geant4 (and Geant3);
use different sensitivities of sub-detectors (energy loss, track use different sensitivities of sub-detectors (energy loss, track multiplicities, shower shapes…) to estimate Geant4 multiplicities, shower shapes…) to estimate Geant4 performance;performance;
tune Geant4 models (“physics lists”) and parameters (range tune Geant4 models (“physics lists”) and parameters (range cut) for optimal representation of the experimental detector cut) for optimal representation of the experimental detector signal with ALL relevant repects;signal with ALL relevant repects;
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G4 validation comparisons
Muon energy loss and secondaries production in the ATLAS Muon energy loss and secondaries production in the ATLAS calorimeters and muon detectorscalorimeters and muon detectors
Electromagnetic shower Electromagnetic shower simulations in calorimeterssimulations in calorimeters
Hadronic interactions in tracking Hadronic interactions in tracking devices and calorimeters devices and calorimeters
(Different showering models
in Geant3 and Geant4)
Reconstructed Energy [GeV]0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
Reconstructed Energy [GeV]
Δ e
vents
/0.1
GeV
[%
]Fra
ctio
n e
vents
/0.1
GeV
10-4
10-3
10-2
10-1
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Eμ= 100 GeV, ημ ≈ 0.975
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G4 Validation (continued)
Geant4 can simulate relevant features of muon, electron and Geant4 can simulate relevant features of muon, electron and pion signals in various ATLAS detectors, often better than pion signals in various ATLAS detectors, often better than Geant3;Geant3;
Remaining discrepancies, especially for hadrons, are being Remaining discrepancies, especially for hadrons, are being addressed and progress can be expected in the near future;addressed and progress can be expected in the near future;
ATLAS can has a huge amount of the right testbeam data for ATLAS can has a huge amount of the right testbeam data for the calorimeters, inner detector modules, and the muon the calorimeters, inner detector modules, and the muon detectors to evaluate the Geant4 physics models in detail;detectors to evaluate the Geant4 physics models in detail;
feedback loops to Geant4 team are for most systems feedback loops to Geant4 team are for most systems established since quite some time; communication is not a established since quite some time; communication is not a problem;problem;
Few people in US involved in G4 validation studies Few people in US involved in G4 validation studies I don’t think anyone from US is a member of the G4 team
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Sub-System Reconstruction
Extensive involvement by US people, primarily in:Extensive involvement by US people, primarily in: LAr, Tile and Muon reconstruction Combined reconstruction: egamma, Jets, tau’s and MissingET
The overall reconstruction chain is functional, a lot of the fortran The overall reconstruction chain is functional, a lot of the fortran code has been rewritten in C++, albeit several missing pieces code has been rewritten in C++, albeit several missing pieces and far from perfect.and far from perfect.
Most of the effort is focussed on:Most of the effort is focussed on: Validation Calibration issues Test Beam Analysis Standardizing the EDM and Detector Description usage
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Database/Detector Description
Support for ROOT persistency for current Detector Description & some Support for ROOT persistency for current Detector Description & some Event Data Objects (Hong Ma, BNL who also coordinates ATLAS LAr Event Data Objects (Hong Ma, BNL who also coordinates ATLAS LAr database activities)database activities)
LAr Database/Detector Description activitiesLAr Database/Detector Description activities
Designed interfaces for accessing conditions data in Athena. Implemented interim solution for conditions data in MySQL for MC simulation, reconstruction, and some testbeam analysis.
Provide requirements input to ATLAS Conditions DB development
Detector Description: 2-day workshop at BNL (12/16/02) to discuss the adoption of the new Detector Description Architecture in LAr Simu/Rec.
Tile Database activities coordinated by Tom Lecompte (ANL)Tile Database activities coordinated by Tom Lecompte (ANL)
Similar activities as those for LAr.
Muon database and detector descriptionMuon database and detector description
XML detector description: MDTs, RPCs, TGCs implemented
Identifier scheme for Muons implemented by Goldfarb, Assamagan
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Calorimeter Reconstruction
Liquid Argon : Liquid Argon : H. Ma, S. Rajagopalan (BNL), P. Loch (Arizona)H. Ma, S. Rajagopalan (BNL), P. Loch (Arizona) Tile Calorimeter : Tile Calorimeter : A. Gupta, F. Merritt (Chicago)A. Gupta, F. Merritt (Chicago) Combined Calorimeter Data Classes and AlgorithmsCombined Calorimeter Data Classes and Algorithms
SimulationSimulation OnlineOnline OfflineOfflineReconstructionReconstruction
CombinedCombinedReconstructionReconstruction
LArHitLArDigit
LArRawCaloCell
CaloTower
CaloClusterTileHitTileDigit
TileRaw
SimpleTrack
egamma
ProtoJet/Jet
tauObject
MissingET
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1MB at t=0+ 25 bunch crossings with10 interactions each
(E not corrected for sampling fraction)
Expected elec. noise reduction from optimal filtering
Pile up increase
(note: OF coeff used are the sameIn real life, they will change with luminosity
Middle SamplingEM Barrel
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Recent Plots using LAr recon. program
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ATLAS Muon Software J. Shank (Boston U.) is the overall software coordinatorJ. Shank (Boston U.) is the overall software coordinator
Muon Database activities coordinated by S. Goldfarb (Michigan)
Current activity:Current activity: OO muon reconstruction (Moore) development
Contributors: G. Stavropolous (LBNL), K. Assamagan (BNL)
Integrated into Athena; in repository; in early development
Migration to new Event Data Model
Clusterization for MDT and CSC completed
Makes use of common track fitting and data classes with InDet Reco
Material Integration Service being implemented Muon database and detector description
Conditiond DB and Athena Testbeam work for the April run. J. Rothberg (U. Wash)
Identifers & detector description by Goldfarb, Assamagan
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ATLAS Muon Database Contributions
Descriptions of Barrel Toroid (left)
and H8 test beam geometry (below).
Both geometries were generated using
compact AGDD syntax and both were
developed by REU summer students,
under the supervision of S. Goldfarb.
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Raw Data Flow
Raw Data Flow Model establishedRaw Data Flow Model established London Meeting: (D.Quarrie & S. Rajagopalan met with London Meeting: (D.Quarrie & S. Rajagopalan met with
HLT to discuss their software design) HLT to discuss their software design) Established strategy on use of Athena/StoreGate in HLT
Data Converters (Hong Ma, BNL): Data Converters (Hong Ma, BNL): Simulation of ROB data and establishing relevant services ByteStream Raw Data and Calibrated Objects for use in
L2, L3 coordinated across all sub-systems by Hong Ma (and implemented for Liquid Argon)
Being implemented for Muons (K. Assamagan, BNL) Efficient on demand access to data in Regions of Interest
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Simulation Data Flow
Generator McTruth(Gen)HepMC
ROD EmulationAlgorithm
L1 Digitization
Particle Filter Simulation
PileUp
McTruth(Sim)HitsROD Input
Digits
McTruth(PileUp)
DigitizationRawDataObjects
ByteStreamConversionSvc
MergedHits
L1Digits
L2Result
EFResult
L1 Emulation(inc. L1 ROD)
L1Result
ROD Emulation
(passthru)
L2 SelectionAlgorithm
EF SelectionAlgorithm
ByteStream
Use
s R
aw
Da
taO
bje
cts
ATLAS
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Validation of Athena for HLT Use
The ATLAS EF will use selection and classification algorithms derived The ATLAS EF will use selection and classification algorithms derived
from the offline suitefrom the offline suite
Offline software performance therefore has a direct impact on EF farm Offline software performance therefore has a direct impact on EF farm
size and costsize and cost
The HLT community has started “validation studies” (detailed The HLT community has started “validation studies” (detailed
benchmarking) of Athena, offline algorithms, and event modelbenchmarking) of Athena, offline algorithms, and event model
The aim is to set metrics for monitoring trends in software performanceThe aim is to set metrics for monitoring trends in software performance
It is clear that the software is presently far from adequateIt is clear that the software is presently far from adequate Not fair to judge during development phase But benchmarking can (and has) helped spur improvements Feedback during monthly meetings with A-team and regular interactions with
developers
Software performance is also important for offline – hope that offline Software performance is also important for offline – hope that offline
community will continue this workcommunity will continue this work
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Combined Reconstruction
egamma Reconstruction egamma Reconstruction Algorithms developed by H. Ma, S. Rajagopalan (BNL) Algorithms to associate clusters and tracks and analyze variables necessary
for e identification (shower shapes, isolation, E/p, …) Calorimeter Cluster calibration (J. McDonald, Pittsburgh)
Jet ReconstructionJet Reconstruction Jet Algorithms (KT and cone) developed by A. Gupta, F. Merritt (Chicago) Jet and Tau Calibration (F. Paige, H. Ma, S. Rajagopalan) (BNL)
H1 style calibration adopted : Provides weighting at a cell level. EM showers are denser than hadronic showers: Cells with dense energy
deposition are weighted toward EM scale. Effective in improving linearity and resolution over standard techniques
(sampling weights).
Missing ET ReconstructionMissing ET Reconstruction
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Physics validation
DC1 data production includes datasets from single electrons, pions, DC1 data production includes datasets from single electrons, pions, di-jet events to full physics events with & without pile-up using G3.di-jet events to full physics events with & without pile-up using G3.
Much of this data is already being analyzed to extract the relevant
calibration constants that is fed back into the process for full
reconstruction. One of the physics signatures fully simulated is 50k SUSY events at One of the physics signatures fully simulated is 50k SUSY events at
the following msugra point : (I. Hinchliffe, F. Paige driving this effort)the following msugra point : (I. Hinchliffe, F. Paige driving this effort)
m0=100, m1/2=300, A0=-300, tan=6, sign() = +
Rich in leptons (including tau’s), jets, b-jets, high multiplicity hard events which is an ideal candidate to test the software.
Most such signatures have previously been studied only with fast simulation
PCAP review. January 15, 2003PCAP review. January 15, 2003S. Rajagopalan ATLAS Simulation & Reconstruction SoftwareS. Rajagopalan ATLAS Simulation & Reconstruction Software 26
e/Jet identification in SUSY events
First look at First look at 500 events from the SUSY sample : 500 events from the SUSY sample :
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Summary
New ATLAS framework, Athena, enthusiastically embraced by broad spectrum New ATLAS framework, Athena, enthusiastically embraced by broad spectrum
of sub-system community.of sub-system community.
Many US physicists active in code developmentMany US physicists active in code development
Well integrated into overall ATLAS software effort
Schedule: Schedule:
DC 0 12/2001
First phase which provided a useful software continuity check
DC 1 02/2002
Large scale simulation/reconstruction with G3.
Phase 1 ongoing, Phase 2 due in March 2003.
Athens Physics Workshop (May 2003)
DC2 : Will use Geant4, Scheduled for early 2004