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The Forward Liquid Argon Calorimeter of The Forward Liquid Argon Calorimeter of the ATLAS Detectorthe ATLAS Detector
Geant4 Workshop'03Geant4 Workshop'032-6 September. Triumf, Vancouver2-6 September. Triumf, Vancouver
Patricia Méndez Lorenzo. CERN EP/SFT
1. Introduction and Generalities
2. FCAL at TestBeam
3. Simulation of FCAL with Geant4
4. Results of the Simulation
5. Summary 1
Introduction and Generalities
Physics to be done at the LHC
1. Origin of the mass at the electroweak scale; search of Higgs boson
► H γγ for 90<MH<150 GeV
► H ZZ 4l for 130<MH<M
Z
► WW, ZZ fusion with H ZZ, WW l,νν, 2jets for MH up 1 TeV
► pp WH, ZH, ttbar H, H bbbar (Excluded by LEP) for 80<MH<100 GeV
Calorimetry plays a central role on subdetectors design at LHC
2. Deep study of the top and botton quarks
3. Search of new physics: SUSY, technicolours, extra-dimensions....
2
General ATLAS Calorimeter System
Goal:High precision measurements of energy and position of electrons, photons, jets and missing E
T
Requirements:◘ Rapidity coverage◘ Good electron reconstruction ◘ Excellent energy resolution ◘ Accurate measurement of the shower position
Main Elements:◙ One central cryostat barrel and 2T super-conducting solenoid◙ Two endcaps, in each one: one electromagnetic, two hadronic wheels and one forward calorimeter
Hadronic TileCalorimeters
EM AccordionCalorimeters
Hadronic lAr EndCapCalorimeters
Forward lArCalorimeters
3
The ATLAS Forward lAr Calorimeter (FCAL)
Goal of the FCALFull coverage of the system for a good determination of the missing energy (undetected particles as neutrinos)
Design► 1 Electromagnetic copper/liquid argon module (FCAL1)
► 2 Hadronic modules (FCAL2, FCAL3) with tungsten as absorber
Construction► Several prototypes for FCAL1 constructed and tested successfully at Brookhaven and CERN
► Full depth pre-production prototypes for FCAL1 and FCAL2 (Module 0) designed and built in Arizona and Canada in 1998
Barrel EndCap
EM AccordionCalorimeter
Had EndCapCalorimeter
FCALCalorimeter
4
The FCAL at the TestBeam
FCAL1 and FCAL2 prototypes (Module 0) have been tested at CERN in 1998 during a testbeam program with electrons, pions and muons
♦ Detectors and elements includedin the TestBeam Setup included in the Simulation
♦ Description of FCAL moduleas close as possible to realdetectors
FCAL Module 0 test beam in Geant4
Particles enter the setup from the lower left corner
FCAL1 Module 0
FCAL2 Module 0
Cryostat
5
Simulation of FCAL Module 0 with Geant4
Important parts:
Geometry
CryostatEM Module and Had ModulesTestBeam SetUp
Physics
Physical ProcessesInput Particles: electrons
Visualization and histogramming
Visualization packagesAnaphe and Aida
Simulation based on TestBeam'98 data included as a Geant4 advanced example called lAr_calorimeter
6
Simulation of FCAL Module 0 with Geant4
Detector Geometry PartDetector Geometry Part
int main(int argc, char** argv){............
G4RunManager* runManager = new G4RunManager;FCALTestbeamSetup* detector = new FCALTestbeamSetUp;runManager ->SetUserInitialization(detector);
...............
FCALCryostatVolumes FCALTestbeamSetUpSD
FCALEMModule(including
EMParameters.input)
FCALHadModule(including
HadParameters.input)
FCALEMModuleSD FCALHadModuleSD 7
Simulation of FCAL Module 0 with Geant4
Standard Advanced Examples Design for Standard Advanced Examples Design for Definition of Particles and Physical Processes Definition of Particles and Physical Processes
ClassesClasses
► FCALPhysicsList : Standard Particles and Physical Processes defined
► FCALPrimaryGeneratorAction: Definition of X, Y, Z, cos_X, cos_Y, cos_Z for electrons inside
tracks_20GeV.dat, tracks_40GeV.dat, tracks_80GeV.dat and tracks_200GeV.dat in files of 1000 events each.
particleRun ->SetParticlePosition particleRun ->SetParticleMomentumDirection
Defined following parameter definitions inside those files
Standard advanced examples design for the rest of classes 8
Simulation of FCAL Module 0 with Geant4
VisualizationVisualization
Development with OpenGL
All visualization packages includedin FCALVisManager class
Initialization of the drawing via:
(interactively)idle> /control/execute vis.mac
Front View of the System
9
Simulation of FCAL Module 0 with Geant4
5.0.6. Anaphe Implementation of the Aida 3.0 5.0.6. Anaphe Implementation of the Aida 3.0 HistogramsHistogramsMakeFile as simple as possibleMakeFile as simple as possibleifdef G4ANALYSIS_USECPPFLAGS += 'aida-config --include'LDFLAGS += 'aida-config --lib'
Sourcing some startup scripts at CERNSourcing some startup scripts at CERNsetenv G4ANALYSYS_USE 1
setenv PATH ${PATH}: /afs/cern.ch/sw/lhcxx/share/LHCXX/latest/scripts
source /afs/cern.ch/sw/lhcxx/share/LHCXX/latest/scripts
ln -s /afs/cern.ch/sw/lhcxx/share/LHCXX/latest/scripts/* ~/bin/.(just once after the source)The example has been tested using the gcc-2.95.2 compiler inside CERN RedHat 6.1 and 7.3
10
Results of the Simulation
Histograms and NtuplesHistograms and NtuplesThe example produces 6 histograms and ntuples saved in “fcal.his”
Group of histos and ntuples to show the AIDA mechanismus: (included in last release)
Histo1 and Ntuple1 —— > Number of Tracks out of WorldHisto2 and Ntuple2 —— > Number of Secondary ParticlesHisto3 and Ntuple3 —— > Deposited Energy in FCAL1Histo4 and Ntuple4 —— > Deposited Energy in FCAL2
Group of histos and ntuples to compare with data of 1998 test beam: (to include in next release)
Histo5 and Ntuple5 ——> Reconstructed Energy in FCAL1Histo6 and Ntuple6 ——> Reconstructed Energy in FCAL2
11
Results of the Simulation
Comparison between Geant4 and TestBeam Data'98Comparison between Geant4 and TestBeam Data'98
Characteristics of the simulation:Characteristics of the simulation:
♣ Variable to study: Energy deposited in FCAL1 and FCAL2 in the liquid argon of the tube electrode summed into tiles
♣ TestBeam data: ntuples of 5000 events each for 20, 40, 60 and 80 GeV
♣ Initial Simulation Conditions: 1000 electrons are jetted at beam energies of 20, 40, 60 and 80 GeV
♣ Range cut for secondary particles production: 1 mm
♣ Important effects to take into account: noise and digitization has to be parameterized inside the simulation
12
Results of the Simulation
Definition of the variable inside the Simulation
Etilerec
= cMC
x Etilevis
+ Enoise
(defined by event)
Erec
(per event) = Σ Etilerec
cMC
= Monte Carlo electron calibration constant: 1/CMC
= <Evis
>/<Edep
>
Cuts 0.5mm 1.0mm 2.0mmc
MC [%] 1.42 1.41 1.36
Etilevis
= row electron signal recollected in each tile of the moduleE
dep = Total energy deposited inside the module: E
dep = E
beam – E
loss
Eloss
= Energy losses outside the moduleE
noise = correction factor calculated by gaussian smearing centered at 0 and a
width of 8 GeV
13
Results of the Simulation
14
Statistical Test Statistical Test (Thanks to statistics testing team)
Code design to compare Data with Simulation by a p-value test: Probability that both histos are compatible
Test performed for FCAL1 Reconstructed Energy to 20, 40 and 60 GeV
Results of the Simulation
15
Results of the Simulation
16
Chi2 ≈ 300 n.d.f< 90 p-value quite small
p-value very small due to an understimation of the statistical error from test beam data
Quite important for these tests a good error estimation
Further factors to take into accout:
1. Low energy electrons not considered into simulation
2. Constant smearing factor for all events into simulation
Summary
17
♠ A simulation for the module 0 of the lAr calorimeter for the ATLAS detector has been successfully performed with the Geant4 toolkit
♠ Test beam'98 setup included in the simulation
♠ Results included in a Geant4 advanced example
♣ The statistical test results here presented are preliminary, still to be tested
♣ Only FCAL1 reconstructed energy has been checked in the comparison, further data variables have to be included in the whole analysis
♣ 2003 summer data must be tested in the simulation