CBM ECAL CBM ECAL simulation statussimulation status

Prokudin Mikhail Prokudin Mikhail ITEPITEP

OutlineOutline

► Calorimeter modelCalorimeter model► TransportTransport

and start of hit producingand start of hit producing

►Hit producingHit producing summable hitssummable hits

► Fast MCFast MC► ReconstructionReconstruction

cluster findingcluster finding first approximationfirst approximation

► TODOTODO

Calorimeter modelCalorimeter model

► 3 regions with cells 3x3, 3 regions with cells 3x3, 6x6, 12x12 cm6x6, 12x12 cm22

with nonrectangular shapewith nonrectangular shape

► ~20k cells ~20k cells ► Each cellEach cell

PSPS ECAL with 140 layers of lead ECAL with 140 layers of lead

and scintillatorand scintillator

► Idea: use stacks of layers Idea: use stacks of layers of one size (1x1cmof one size (1x1cm22) at ) at transport stage and transport stage and assemble a correct assemble a correct structure at hit producing structure at hit producing stagestage

TransportTransport

►~140 sensitive volumes per stack~140 sensitive volumes per stack if created by means of standard if created by means of standard

frameworkframework►Custom geometry creationCustom geometry creation►Custom geometry filesCustom geometry files

compatibility with frameworkcompatibility with framework all this done by CbmEcalInf classall this done by CbmEcalInf class

►Start hit producing at transport stageStart hit producing at transport stage sum up energy deposited by each particle sum up energy deposited by each particle

in stackin stack

TransportTransport

►Custom Geant cuts for correct shower Custom Geant cuts for correct shower modelingmodeling these cuts used only for ECAL mediumsthese cuts used only for ECAL mediums

►Still using 1x1cmStill using 1x1cm22 stacks stacks for current ECAL geometry 3x3cmfor current ECAL geometry 3x3cm22 is enough is enough but some flexibility for large amount of data but some flexibility for large amount of data

requiredrequired

►Only Geant3 transport is tested and usedOnly Geant3 transport is tested and used

Hit producingHit producing

► Formation of ECAL cells from stacksFormation of ECAL cells from stacks one input data can be used for ECALs with one input data can be used for ECALs with

different cellsdifferent cells and produce a summable hitand produce a summable hit

►summable hits can be used for event mixingsummable hits can be used for event mixing

► Summation of energy deposition from all Summation of energy deposition from all particles in cellparticles in cell

►Noise additionNoise addition two separate values for ECAL and PS celltwo separate values for ECAL and PS cell and formation of hitand formation of hit

►Only one hit producer for all operationsOnly one hit producer for all operations

Fast MCFast MC

►No shower development, only No shower development, only EcalPoints in front calorimeterEcalPoints in front calorimeter to save CPU time and reduce memory to save CPU time and reduce memory

consumptionconsumption

►One class for transport in Fast and Full One class for transport in Fast and Full MCMC to keep ECAL geometry consistentto keep ECAL geometry consistent but different hit and hit producer classesbut different hit and hit producer classes

Hit producing for Fast MCHit producing for Fast MC

►Can be used with full MC filesCan be used with full MC files►Smear particle position and energySmear particle position and energy

Constant energy response for hadronsConstant energy response for hadrons Energy resolution ~5%/sqrt(E) Energy resolution ~5%/sqrt(E) Different position resolution for different Different position resolution for different

regions of ECALregions of ECAL►not consistent with “standard” one, just not consistent with “standard” one, just

rectanglesrectangles Use MC information for particle IDUse MC information for particle ID

►To skip not implemented reconstruction To skip not implemented reconstruction procedureprocedure

Only for rough acceptance estimates

Cluster finderCluster finder

►Combine cells with energy deposition Combine cells with energy deposition more then threshold into clustermore then threshold into cluster to minimize number of particles into to minimize number of particles into

considerationconsideration

►Typical size of cluster for CBM central Typical size of cluster for CBM central event ~1000 cellsevent ~1000 cells useless?useless?

Procedure of Procedure of γγ reconstruction reconstruction

►First First approximationapproximation energyenergy

►calibrationcalibration

positionposition►S-curvesS-curves

►Cluster unfoldingCluster unfolding shower shapeshower shape

►shower libraryshower library

► LHCb like methodsLHCb like methods► Pure Pure γγ,, no background no background► Simple and easy to checkSimple and easy to check► Test site for shower Test site for shower

library routineslibrary routines► Can be done in few Can be done in few

monthmonth

► ALICE-like methodsALICE-like methods► Require much more effortRequire much more effort

CALO parameters should be fixed?CALO parameters should be fixed?

From September CBM collaboration meeting

Don

e

Calibration data storingCalibration data storing

► Reconstruction Reconstruction algorithms needs data algorithms needs data forfor energy calibrationenergy calibration

► only energy deposited in only energy deposited in scintillator seen in scintillator seen in calorimetercalorimeter

positionposition► via S-curvesvia S-curves

shower shapeshower shape► shower library?shower library?

► Way of data storing?Way of data storing? .root files for S-curve and.root files for S-curve and variables in scripts for variables in scripts for

calibration are used at calibration are used at the momentthe moment

a=0.00348±3.775e-5

b=0.07859±1.293e-5

Calibration curve for θ=0º for inner cells

ReconstructionReconstruction

►No reconstruction implementationNo reconstruction implementation in terms of frameworkin terms of framework

► Unfolding procedure is missingUnfolding procedure is missing► First approximation forFirst approximation for

position: CbmEcalSCurveLib classposition: CbmEcalSCurveLib class energy: no container class at the momentenergy: no container class at the moment

►No information from tracker in calorimeterNo information from tracker in calorimeter no particle IDno particle ID no peak position correctionno peak position correction

TODOTODO

► Check simulation with new version of Check simulation with new version of CBMROOTCBMROOT calibrationcalibration

► Reconstruction procedure requireReconstruction procedure require cluster unfoldingcluster unfolding

►shower library?shower library?

tracking informationtracking information

►New ECAL geometryNew ECAL geometry two arms?two arms?

► Add light collection details into simulationAdd light collection details into simulation MC model of scintillator plate is requiredMC model of scintillator plate is required