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Forum: Hadronic Processes
Date: 08 Jan, 2015
From: <Santos>

Dear all,

I am checking my physics list by simulating neutron-Aluminum elastic scattering at 10MeV neutron incident energy. I am attaching the output that I got (alum121114b.png) and the plot from nndc (nAlElasNNDC10MeV.gif). While the central parts look similar, at backwards and forward angles my simulation has strange drop-offs that should not be there. The pictures I am attaching were produced with 9.6p02, but, upon installing the latest version, geant10, and bringing the program up to its standards, I got something very similar.

Could anybody, please, advise me on what is going on?

Here is the piece of stepping action where I fill the histograms:

  if(processname=="hadElastic" && (volname=="Target" || volname=="Target_phys") ){
      G4double polarAng = aTrack->GetMomentum().theta();
      //      G4cout << " Inside if "<<polarAng/deg<<" degrees" << G4endl;
      // outfile << polarAng/deg << G4endl;
      aTrack->SetTrackStatus(fKillTrackAndSecondaries);

      if(polarAng>=1.*deg)
	histoManager->FillHisto1d(0,polarAng/deg);
      histoManager->FillHisto1d(1,polarAng/deg);
    }

"Target" and "Target_phys" represent an unfortunate naming convention for the target and target holder (I made both aluminum).

My hadronic physics, heavily borrowed from an example is here:
// "Hadronic"
void ConstructHadr()
{
  SetBuilderList(true);
  //  hadrPhysicsList.push_back( new HadronPhysicsQGSP_BERT_HP());
  hadrPhysicsList.push_back( new HadronPhysicsQGSP_BIC_HP());
  //  hadrPhysicsList = new HadronPhysicsQGSP_BERT_HP();
  G4cout<<"hadrPhysicsList.size() "<<hadrPhysicsList.size()<<G4endl;
  //  std::cin.ignore(); std::cin.get();
  for(unsigned int ctr=0;ctr<hadrPhysicsList.size();ctr++){
    G4cout<<"ctr "<<ctr<<G4endl;
    hadrPhysicsList.at(ctr)->ConstructProcess();
  }
  G4cout<<"after construction"<<G4endl;
  //  return;
}

// extra processes for hadronic to work (from Hadr01 example)
void SetBuilderList(G4bool flagHP)
{
  hadrPhysicsList.push_back( new G4EmExtraPhysics(verboseLevel));
  if(flagHP) {
    hadrPhysicsList.push_back( new G4HadronElasticPhysicsHP(verboseLevel) );
  } else {
    hadrPhysicsList.push_back( new G4HadronElasticPhysics(verboseLevel) );
  }
  hadrPhysicsList.push_back( new G4QStoppingPhysics(verboseLevel));
  hadrPhysicsList.push_back( new G4IonPhysics(verboseLevel));
  hadrPhysicsList.push_back( new G4NeutronTrackingCut(verboseLevel));
}

Thank you for any input

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/01/08/13.29-17273-alum121114b.png
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/01/08/13.29-75303-nAlElasNNDC10MeV.gif

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1 Idea: Re: Forward/backward angles in n-Al elastic scattering   (Vladimir Ivanchenko - 07 Feb, 2015)
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