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Published byAnis Atkinson Modified over 9 years ago
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CBM ECAL simulation status Prokudin Mikhail ITEP
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Outline ► Calorimeter model ► Transport and start of hit producing ► Hit producing summable hits ► Fast MC ► Reconstruction cluster finding first approximation ► TODO
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Calorimeter model ► 3 regions with cells 3x3, 6x6, 12x12 cm 2 with nonrectangular shape ► ~20k cells ► Each cell PS ECAL with 140 layers of lead and scintillator ► Idea: use stacks of layers of one size (1x1cm 2 ) at transport stage and assemble a correct structure at hit producing stage
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Transport ► ~140 sensitive volumes per stack if created by means of standard framework ► Custom geometry creation ► Custom geometry files compatibility with framework all this done by CbmEcalInf class ► Start hit producing at transport stage sum up energy deposited by each particle in stack
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Transport ► Custom Geant cuts for correct shower modeling these cuts used only for ECAL mediums ► Still using 1x1cm 2 stacks for current ECAL geometry 3x3cm 2 is enough but some flexibility for large amount of data required ► Only Geant3 transport is tested and used
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Hit producing ► Formation of ECAL cells from stacks one input data can be used for ECALs with different cells and produce a summable hit ► summable hits can be used for event mixing ► Summation of energy deposition from all particles in cell ► Noise addition two separate values for ECAL and PS cell and formation of hit ► Only one hit producer for all operations
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Fast MC ► No shower development, only EcalPoints in front calorimeter to save CPU time and reduce memory consumption ► One class for transport in Fast and Full MC to keep ECAL geometry consistent but different hit and hit producer classes
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Hit producing for Fast MC ► Can be used with full MC files ► Smear particle position and energy Constant energy response for hadrons Energy resolution ~5%/sqrt(E) Different position resolution for different regions of ECAL ► not consistent with “standard” one, just rectangles Use MC information for particle ID ► To skip not implemented reconstruction procedure Only for rough acceptance estimates
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Cluster finder ► Combine cells with energy deposition more then threshold into cluster to minimize number of particles into consideration ► Typical size of cluster for CBM central event ~1000 cells useless?
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Procedure of γ reconstruction ► First approximation energy ► calibration position ► S-curves ► Cluster unfolding shower shape ► shower library ► LHCb like methods ► Pure γ, no background ► Simple and easy to check ► Test site for shower library routines ► Can be done in few month ► ALICE-like methods ► Require much more effort CALO parameters should be fixed? From September CBM collaboration meeting Done
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Calibration data storing ► Reconstruction algorithms needs data for energy calibration ► only energy deposited in scintillator seen in calorimeter position ► via S-curves shower shape ► shower library? ► Way of data storing? .root files for S-curve and variables in scripts for calibration are used at the moment a=0.00348±3.775e-5 b=0.07859±1.293e-5 Calibration curve for θ=0º for inner cells
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Reconstruction ► No reconstruction implementation in terms of framework ► Unfolding procedure is missing ► First approximation for position: CbmEcalSCurveLib class energy: no container class at the moment ► No information from tracker in calorimeter no particle ID no peak position correction
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TODO ► Check simulation with new version of CBMROOT calibration ► Reconstruction procedure require cluster unfolding ► shower library? tracking information ► New ECAL geometry two arms? ► Add light collection details into simulation MC model of scintillator plate is required
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