CBM ECAL simulation status Prokudin Mikhail ITEP

Outline ► Calorimeter model ► Transport  and start of hit producing ► Hit producing  summable hits ► Fast MC ► Reconstruction  cluster finding  first approximation ► TODO

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

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

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

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

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

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

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?

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

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= ±3.775e-5 b= ±1.293e-5 Calibration curve for θ=0º for inner cells

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

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