Revision as of 15:28, 22 November 2021

Configure example

There is an example of running the entire chain from generating particles to running an analysis tool. A more detailed description of the algorithms and their parameters is presented below.

from Configurables import ApplicationMgr

from Gaudi.Configuration import *
from Configurables import GenAlg, EvtGenInterface
from Configurables import HepMCToEDMConverter
from Configurables import ScTauDataSvc

from Configurables import Gaudi__ParticlePropertySvc
from PathResolver import PathResolver

############################
####  Event generation  ####
############################
podioevent = ScTauDataSvc("EventDataSvc")

# Particle service
particlePropertySvc = Gaudi__ParticlePropertySvc(
    "ParticlePropertySvc",
    ParticlePropertiesFile=PathResolver.FindDataFile('GenParticleData/ParticleTable.txt')
)

# EvtGen
evtgen = EvtGenInterface('SignalProvider')
#evtgen.userdec = "./mydec.dec"
#evtgen.rootParticle = "J/psi"

gen = GenAlg('EvtGenAlg', SignalProvider=evtgen)
gen.hepmc.Path = 'hepmc'

# HepMC3 to PODIO
edm = HepMCToEDMConverter("Converter")
edm.hepmc.Path=gen.hepmc.Path
edm.genparticles.Path="allGenParticles"
edm.genvertices.Path="allGenVertices"

############################
# SctParSim
############################
from Configurables import SctParSimAlg

sct_alg = SctParSimAlg('SctAlg')
#sct_alg.CaloSystemTool.caloClSizeEGamma = 0.2 # Example how to change a subsystem parameter

############################
# Podio output
############################
out = PodioOutput('out', filename=ofile)
out.outputCommands = ["keep *"]

############################         
# Analisis                           
############################ 
from Configurables import EventLoader
from Configurables import NtupleAlg, NTupleSvc
from Configurables import ParticleCombinerAlg

evlo = EventLoader('EvtLoader')
evlo.pcl.Path = 'Particles' # Branch (in the input ROOT-file) for reading
evlo.pListMap.Path = 'Lists1'
evlo.plists = [['gamma']] # Partilce list for further analisis

# Select particle combinations       
cmbr = ParticleCombinerAlg('Cmbr',
    decStr = 'pi0 -> gamma gamma', # Investigated decay
    cutStr = 'E > 0.5', # Selection criteria
    selfConj = True # if neutral particle True, else False
)

cmbr.pListMapI = evlo.pListMap.Path 
cmbr.pListMapO.Path = 'Lists2' 

# Select variables to save to n-tuple
tupl = NtupleAlg('piTuple') 
tupl.listName = 'pi0'
tupl.fileName = 'scttuple/tup'

# List contains the particle parametes to write an output file
tupl.vars = [['px_mc', 'py_mc', 'pz_mc', 'E', 'pi0 -> ^gamma ^gamma'],
    ['M', ''],
]

tupl.pListMapI.Path = cmbr.pListMapO.Path
NTupleSvc(Output = ["scttuple DATAFILE='tup.root' OPT='NEW' TYP='ROOT'"])


############################         
# Running algorithms                 
############################ 

options= {
    'TopAlg' : [gen, edm, sct_alg, evlo, cmbr, tupl, out],
    'EvtSel' : 'NONE',
    'ExtSvc' : [particlePropertySvc, podioevent],
    'EvtMax' : 10000,
    'StatusCodeCheck' : True,
    'AuditAlgorithms' : True,
    'AuditTools'      : True,
    'AuditServices'   : True,
    'OutputLevel'     : INFO,
    'HistogramPersistency' : 'ROOT',
}

ApplicationMgr(**options)

Event generation

The "Event generation" block may contain other options: to read a ROOT file, to generate using the particle gun tool and to generate using EvtGen.

Podio input

It is possible to read the particle parameters from a ROOT file.

You have to import the library

from Configurables import PodioInput

and to create the algorithm instance

podioevent = ScTauDataSvc("EventDataSvc", input="fileName.root")
podioinput = PodioInput("PodioReader", OutputLevel=INFO, collections=['allGenParticles'])

The important parametres:

• input - an input file name
• collections - a name of a branch with MC particles

Particle gun

To use the particle gun algorithm, it is necessary to import the following libraries

from Configurables import ParticleGun
from Configurables import GenAlg
from Configurables import HepMCToEDMConverter
from Configurables import HepMCFileWriter

from Configurables import Gaudi__ParticlePropertySvc
from PathResolver import PathResolver

and to write the following strings

particlePropertySvc = Gaudi__ParticlePropertySvc(
    "ParticlePropertySvc",
    ParticlePropertiesFile=PathResolver.FindDataFile('GenParticleData/ParticleTable.txt')
)

from math import pi
guntool = ParticleGun("PdgCodes", PdgCodes=[211])
guntool.OutputLevel=DEBUG

guntool.MomentumMin = 0 * units.MeV 
guntool.MomentumMax = 4 * units.GeV

guntool.ThetaMin = 0 * units.rad 
guntool.ThetaMax = pi * units.rad 

guntool.PhiMin = 0 * units.rad
guntool.PhiMax = 2 * pi * units.rad 

gun = GenAlg("ParticleGun", SignalProvider=guntool)
gun.hepmc.Path = "hepmc"

writer = HepMCFileWriter("HepMCFileWriter")
writer.hepmc.Path="hepmc"

hepmc_converter = HepMCToEDMConverter("Converter")
hepmc_converter.hepmc.Path="hepmc"
hepmc_converter.genparticles.Path="allGenParticles"
hepmc_converter.genvertices.Path="allGenVertices"

Some parameters can be changed:

• PdgCodes - a list containing particles PDG codes to generate
• MomentumMin - a minimum particle momentum
• MomentumMax - a maximum particle momentum
• ThetaMin - a minimum theta angle
• ThetaMax - a maximum theta angle
• PhiMin - a minimum phi angle
• PhiMax - a maximum phi angle

EvtGen

SctParSim

Analysis

Podio output