Transcript Status of Shower Parameterisation code in Athena Andrea Dell’Acqua CERN PH-SFT.

Status of Shower Parameterisation code in Athena
Andrea Dell’Acqua CERN PH-SFT
<[email protected]>
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Who
 Most of the implementation work (and interfacing to Athena)
done by Anthony Waugh (Univ. of Sydney)
 Still willing to spend a significant fraction of his time on
this subject but shifting emphasis
 State of the art presented by Anthony at the recent LAr week
 Available at:
http://indico.cern.ch/conferenceDisplay.py?confid=a062981
 Most of the gibbering here by me
 Apologies if I misrepresent anything/anybody
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What
 Use G4 parameterisation interface “as is”
 Re-implement
G4Flash-like
shower
parameterisation
procedure and customize it to the case of ATLAS LAr
calorimeters
 Concentrate on the LAr calorimeters
 There is no reason why Tilecal can not be included, it was
just a (wo)manpower issue until now
 Stick to EM physics yet
 Is there a need of parameterising hadronic interactions? Is
there a safe way of parameterising hadronic interactions in
ATLAS?
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How
 Fast simulation scheme
 Only electrons/positrons are parameterised. Photons are
followed by full sim. up to the point they convert (only then
parameterisation kicks in)
 Particles must be within allowable energy range, if not
use full simulation
 Shower must be contained within the calorimeter, in
Z(95%) and R(95%). If not return to full simulation. When a
fully contained electron is produced, it is parameterised
 Showers starting before the calorimeter are handled by
full simulation. Each particle entering the calorimeter is then
handled separately by parameterisation mechanism
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How (2)
 If all boundary conditions are satisfied
 The track is killed
 Fake steps (10mm) are simulated along the initial electron
trajectory. Energy deposited and nr. of spots per steps are
calculated
 Sampling fluctuations are calculated, according to calo
resolution
 Energy and position of each spot are calculated
 Fake steps are filled up and given to (standard) sensitive
detector classes to generate hits
 Standard simulation chain utilized to process hits
 Loop until the total shower energy is deposited
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Full vs. Fast
 Shower profiles for EM barrel (10GeV e-)
 BLUE - Full sim. RED - fast sim.
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Full vs. fast (2)
 Shower profiles for EM endcap (10GeV e-)
 BLUE - Full sim. RED - fast sim.
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Full vs. fast (3)
 Shower profiles for FCAL (10GeV e-)
 BLUE - Full sim. RED - fast sim.
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Simulation time
 Shower simulation time (electrons) for full and fast
simulation
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What is available?
 In release 12.0.1
 All machinery in place and working
 Add (to standard job options)
SimFlags.CalibrationRun.set_Value('')
…
AtlasG4Eng.G4Eng.add_FastSimModel("LArG4FastSimulation","LArFastShower","LArMgr::LAr::EMB::STAC")
AtlasG4Eng.G4Eng.add_FastSimModel("LArG4FastSimulation","LArFastShower","LArMgr::LAr::EMEC::OuterWheel")
AtlasG4Eng.G4Eng.add_FastSimModel("LArG4FastSimulation","LArFastShower","LArMgr::LAr::EMEC::InnerWheel")
AtlasG4Eng.G4Eng.add_FastSimModel("LArG4FastSimulation","LArFastShower","LArMgr::LAr::FCAL::Module1::Absorber")
 Parameterised models CAN NOT be used together with calibration
hits (obvious) but they don’t seem to go together with dead material
hits either! To be understood and fixed…
 Currently limited to LAr calorimeters only
 Event sample (single particles) to be added to the standard test
production exercise
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What remains to be done?
 Extend shower parameterisation to Tile/HEC/HadFCAL
 Repackage code (currently in
LArCalorimeter/LArG4/LArG4FastSimulation )
 Make steering parameters accessible via python/JO
 G4 8.x coming along, require interface change (backwards incompatible)
 Test, validate, improve
 Single particles, full events
 EM component of hadronic showers
 Different (coarser?) parameterisation models
 Speed?
 Understand physics requirements and figure out physics channel specific
parameterisation strategies
 Where can we gain? How much? Is it worth the hassle?
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