CBM ECAL simulation status

1
CBM ECAL simulation status

• Prokudin Mikhail ITEP

2
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 cm2
• with nonrectangular shape
• 20k cells
• Each cell
• PS
• ECAL with 140 layers of lead and scintillator
• Idea use stacks of layers of one size (1x1cm2)
  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 1x1cm2 stacks
• for current ECAL geometry 3x3cm2 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 ? reconstruction

• First approximation
• energy
• calibration
• position
• S-curves
• Cluster unfolding
• shower shape
• shower library

• LHCb like methods
• Pure ?, no background
• Simple and easy to check
• Test site for shower library routines
• Can be done in few month

Done

• ALICE-like methods
• Require much more effort
• CALO parameters should be fixed?

From September CBM collaboration meeting
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Calibration data storing
Calibration curve for ?0º for inner cells

• 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

a0.003483.775e-5 b0.078591.293e-5
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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