AddDiMuonDecayChannelsToG4.py

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# SPDX-License-Identifier: LGPL-3.0-or-later
# SPDX-FileCopyrightText: Copyright CERN for the benefit of the SHiP Collaboration
 
import ROOT
 
ROOT.gROOT.ProcessLine('#include "Geant4/G4ParticleTable.hh"')
ROOT.gROOT.ProcessLine('#include "Geant4/G4DecayTable.hh"')
ROOT.gROOT.ProcessLine('#include "Geant4/G4PhaseSpaceDecayChannel.hh"')
 
 
def Initialize(p8):
    # take decay and branching ratios from Pythia8
    pt = ROOT.G4ParticleTable.GetParticleTable()
    for vreso in [223, 333, 113]:
        particleG4 = pt.FindParticle(vreso)
        particleP8 = p8.particleData.particleDataEntryPtr(vreso)
        decayTable = ROOT.G4DecayTable()
        for i in range(particleP8.sizeChannels()):
            achannel = particleP8.channel(i)
            bR = achannel.bRatio()
            mul = achannel.multiplicity()
            dl = []
            for daughter in range(4):
                if daughter < mul:
                    pid = achannel.product(daughter)
                    dl.append(pt.FindParticle(pid).GetParticleName())
                else:
                    dl.append(ROOT.G4String(""))
            mode = ROOT.G4PhaseSpaceDecayChannel(particleG4.GetParticleName(), bR, mul, dl[0], dl[1], dl[2], dl[3])
            decayTable.Insert(mode)
        particleG4.SetDecayTable(decayTable)
        particleG4.DumpTable()