Force Lambdas to decay into protons and pions (#2284)

* force the Lambda to decay into proton and pion

* generate lambdas with pt > 0.6 GeV/c

* remove unneccessary configuration

* fix nevents

---------

Co-authored-by: Chiara De Martin <chdemart@alicecerno2.cern.ch>

Author: ChiaraDeMartin95

MC/config/PWGLF/ini/GeneratorDoubleLambdaTriggered.ini

@@ -1,6 +1,6 @@
 [GeneratorExternal]
 fileName=${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGLF/pythia8/generator_pythia8_doubleLambdas.C
-funcName=generateDoubleLambda(1, 0.2, 10, 0.8)
+funcName=generateDoubleLambda(1, 0.6, 10, 0.8)
 
 [GeneratorPythia8] 
 config=${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGLF/pythia8/generator/pythia8_inel_ropes_136tev.cfg

MC/config/PWGLF/pythia8/decayer/force_lambda_charged_decay.cfg

@@ -0,0 +1,5 @@
+3122:mayDecay = on
+3122:oneChannel = 1 1.0 0 2212 -211
+
+-3122:mayDecay = on
+-3122:oneChannel = 1 1.0 0 -2212 211

MC/config/PWGLF/pythia8/decayer/g4_ext_decayer_lambda.in

@@ -0,0 +1,68 @@
+
+/control/verbose 2
+/mcVerbose/all 1
+/mcVerbose/geometryManager 1
+/mcVerbose/opGeometryManager 1
+/mcTracking/loopVerbose 1
+/mcVerbose/composedPhysicsList 2
+/mcVerbose/runAction 2   # For looping thresholds control
+#/tracking/verbose 1
+#//control/cout/ignoreThreadsExcept 0
+
+/mcPhysics/rangeCuts 0.001 mm
+/mcRegions/setRangePrecision 5
+/mcTracking/skipNeutrino true
+/mcDet/setIsMaxStepInLowDensityMaterials true
+/mcDet/setMaxStepInLowDensityMaterials 10 m
+/mcMagField/setConstDistance 1 mm
+/mcDet/setIsZeroMagField true
+/mcControl/useRootRandom true # couple G4 random seed to gRandom
+
+# optical
+
+/process/optical/verbose 0
+/process/optical/processActivation Scintillation 0
+/process/optical/processActivation OpWLS 0
+/process/optical/processActivation OpMieHG 0
+/process/optical/cerenkov/setTrackSecondariesFirst false
+/mcMagField/stepperType NystromRK4
+
+# PAI for TRD
+# Geant4 VMC >= v3.2
+/mcPhysics/emModel/setEmModel  PAI
+/mcPhysics/emModel/setRegions  TRD_Gas-mix
+/mcPhysics/emModel/setParticles  all
+/mcPrimaryGenerator/skipUnknownParticles true # don't crash when seeing unknown ion etc. (issue warning)
+
+#
+# Precise Msc for EMCAL
+#
+# Geant4 VMC >= v3.2
+/mcPhysics/emModel/setEmModel  SpecialUrbanMsc
+/mcPhysics/emModel/setRegions  EMC_Lead$ EMC_Scintillator$
+/mcPhysics/emModel/setParticles  e- e+
+
+# combined transportation + Msc mode is currently broken for ALICE (Geant 10.2.0)
+/process/em/transportationWithMsc Disabled
+
+#
+# Adding extra lines for fixing tracking bias
+#
+/mcMagField/setDeltaIntersection  1.0e-05 mm
+/mcMagField/setMinimumEpsilonStep 0.5e-05
+/mcMagField/setMaximumEpsilonStep 1.0e-05
+/mcMagField/printParameters
+
+# Change default parameters for killing looping particles
+#
+/mcPhysics/useHighLooperThresholds
+/mcRun/setLooperThresholdImportantEnergy 100. MeV
+
+# Define media with the INCLXX physics list; here basically in all ITS media
+#/mcVerbose/biasingConfigurationManager 3
+/mcPhysics/biasing/setModel inclxx
+/mcPhysics/biasing/setRegions ITS_AIR$ ITS_WATER$ ITS_COPPER$ ITS_KAPTON(POLYCH2)$ ITS_GLUE_IBFPC$ ITS_CERAMIC$ ITS_K13D2U2k$ ITS_K13D2U120$ ITS_F6151B05M$ ITS_M60J3K$ ITS_M55J6K$ ITS_FGS003$ ITS_CarbonFleece$ ITS_PEEKCF30$ ITS_GLUE$ ITS_ALUMINUM$ ITS_INOX304$ ALPIDE_METALSTACK$ ALPIDE_SI$
+/mcPhysics/biasing/setParticles proton neutron pi+ pi-
+
+# external decayer
+/mcPhysics/setExtDecayerSelection lambda anti_lambda

MC/run/PWGLF/run_DoubleLambdaTriggered.sh

@@ -26,10 +26,12 @@ echo "NWORKERS = $NWORKERS"
 
 # create workflow
 O2_SIM_WORKFLOW=${O2_SIM_WORKFLOW:-"${O2DPG_ROOT}/MC/bin/o2dpg_sim_workflow.py"}
+CFGDECAY="${O2DPG_ROOT}/MC/config/PWGLF/pythia8/decayer/force_lambda_charged_decay.cfg"
+G4CFG="${O2DPG_ROOT}/MC/config/PWGLF/pythia8/decayer/g4_ext_decayer_lambda.in"
 $O2_SIM_WORKFLOW -eCM ${ENERGY} -col ${SYSTEM} -gen external \
         -j ${NWORKERS} \
         -ns ${NSIGEVENTS} -tf ${NTIMEFRAMES} -interactionRate ${INTRATE} \
-        -confKey "Diamond.width[2]=6." \
+        -confKey "Diamond.width[0]=0.1;Diamond.width[1]=0.1;Diamond.width[2]=6.;;DecayerPythia8.config[1]=${CFGDECAY};DecayerPythia8.showChanged=1;G4.configMacroFile=${G4CFG}" \
         ${SEED} \
         -e ${SIMENGINE} \
         -ini $CFGINIFILE