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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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?

10. 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 Procedure of γ reconstruction Done • ALICE-like methods • Require much more effort • CALO parameters should be fixed? From September CBM collaboration meeting

11. Calibration data storing Calibration curve for θ=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 a=0.00348±3.775e-5 b=0.07859±1.293e-5

12. 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

13. 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