The question to answer: what is difference, measured in numbers of charged SimTracks, between 2 scenarios:

  • PYTHIA performs the decay of hadrons, if the ctau is within the kinematic range of the CMS detector (used in several official simulations scenarios); a note, the pythiaUESettings, already has a decay of unstable particle included, if ctau<10mm. (= 'MSTJ(22)=2 ! Decay those unstable particles', 'PARJ(71)=10 . ! for which ctau 10 mm', =)

import FWCore.ParameterSet.Config as cms
from Configuration.Generator.PythiaUESettings_cfi import *
generator = cms.EDFilter("Pythia6GeneratorFilter",
                         pythiaPylistVerbosity = cms.untracked.int32(1),
                         pythiaHepMCVerbosity = cms.untracked.bool(True),
                         comEnergy = cms.double(4000.0),
                         filterEfficiency = cms.untracked.double(1),
                         crossSection = cms.untracked.double(-1),
                         maxEventsToPrint = cms.untracked.int32(0),
                         PythiaParameters = cms.PSet(
        processParameters = cms.vstring('MSEL=0           ! User defined processes', 
                                        'MSUB(11)=1       ! fifj->fkfl', 
                                        'MSUB(12)=1       ! fifjbar->fkfkbar', 
                                        'MSUB(13)=1       ! fifibar->gg', 
                                        'MSUB(15)=1       ! fifibar->gZ0', 
                                        'MSUB(16)=1       ! fifibar->gW+', 
                                        'MSUB(28)=1       ! fig->fig', 
                                        'MSUB(30)=1       ! fig->fiZ', 
                                        'MSUB(31)=1       ! fig->fiW', 
                                        'MSUB(53)=1       ! gg->fkfkbar', 
                                        'MSUB(68)=1       ! gg->gg', 
                                        'CKIN(3)=10.      ! minimum pt hat for hard interactions',
                                        'CKIN(4)=100.     ! maximum pt hat for hard interactions'
                                    *   ,'MSTJ(22)=4       ! Decay unstable particles in a cylinder', 
                                    *   'PARJ(73)=2000.   ! max. radius for MSTJ(22)=4', 
                                    *   'PARJ(74)=4000.   ! max. Z for MSTJ(22)=4', 
                                    *    'MDCY(C130,1)=1   ! decay k0-longs', 
                                    *    'MDCY(C211,1)=1   ! decay pions', 
                                    *    'MDCY(C321,1)=1   ! decay kaons'
        # This is a vector of ParameterSet names to be read, in this order
        parameterSets = cms.vstring('pythiaUESettings',
  • let GEANT do the decay: comment out the lines marked with =* = in the configuration file above

The way the test was done: generated 4000 events, 2000 for each case, keeping the randomNumbers the same, and looked a the number of SimTracks. The configuration file to recreate these events is this one. The files, with their location are: geantDecay and pythiaDecay.

The results are bellow.

pc_pt_geantPythiaDecay.gif pc_eta_geantPythiaDecay.gif

My conclusion GEANT is doing well, the background samples used for the Detector readiness studies do contain all the possible hadrons and their decay products (with the pythia+hydjet xsections); (the difference between the 2 data sets I blame mostly on: more decays turned on in GEANT (ok, all) compared to the 3 I specifically had on, and the cut, in the 4000 x 2000 strict cut imposed in the case of the pythia decays ) -- CameliaMironov - 18-Dec-2009

Topic attachments
I Attachment History Action Size Date Who Comment
Texttxt r1 manage 10.2 K 2009-12-18 - 00:35 CameliaMironov  
Texttxt r1 manage 10.1 K 2009-12-18 - 00:36 CameliaMironov  
Texttxt r1 manage 4.4 K 2009-12-18 - 00:35 CameliaMironov configuration file to produce the data samples
GIFgif pc_eta_geantPythiaDecay.gif r1 manage 7.4 K 2009-12-18 - 00:34 CameliaMironov  
GIFgif pc_geantPythiaDecay.gif r1 manage 13.2 K 2009-12-18 - 00:33 CameliaMironov  
GIFgif pc_pt_geantPythiaDecay.gif r1 manage 8.5 K 2009-12-18 - 00:34 CameliaMironov  
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Topic revision: r1 - 2009-12-18 - CameliaMironov
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