geant4/source/processes/hadronic/models/isotope_production

                    Geant4 Isotope Production Models
                    --------------------------------

 As of January 2012, the use of the isotope production models had been
 largely superseded, as most inelastic models automatically place the
 residual nucleus on the final state stack where it is readily available
 to users.  Exceptions are the Low Energy Parameterized (LEP) models
 which do not create residual nuclei.  As a result, the isotope
 production models are now used only in conjunction with the LEP models,
 and the infrastructure for isotope production has been moved from the
 process level (G4HadronicProcess) to the model level
 (G4InelasticInteraction).


 Physics List
 ------------
 As before, isotope production can be invoked from the physics list, but
 with some changes.  To enable isotope production, your physics list must
 have the following lines:

 for neutrons:

   if (particleName == "neutron") {
     G4NeutronInelasticProcess* theInelasticProcess =
                                       new G4NeutronInelasticProcess();
     G4LENeutronInelastic* theLEInelasticModel = new G4LENeutronInelastic;

     // Turn on isotope production
     theLEInelasticModel->TurnOnIsotopeProduction();
     G4NeutronIsotopeProduction* aProductionModel =
                                         new G4NeutronIsotopeProduction();
     // Assign a specific model to handle production
     theLEInelasticModel->RegisterIsotopeProductionModel(aProductionModel);

     theInelasticProcess->RegisterMe(theLEInelasticModel);
     pmanager->AddDiscreteProcess(theInelasticProcess);
   }

 The line 
     theLEInelasticModel->TurnOnIsotopeProduction();

 activates for the neutron inelastic model the generic isotope production
 based on the incident particle, target nucleus and produced secondaries.
 It is valid for all incident energies, but does not take into account the
 detailed production cross sections found, for example, in G4NDL.

 If you have an improved model, for example G4NeutronIsotopeProduction,
 it can be added in the subsequent lines:

     G4NeutronIsotopeProduction* aProductionModel =
                                         new G4NeutronIsotopeProduction();
     theLEInelasticModel->RegisterIsotopeProductionModel(aProductionModel);

 Within its energy range of validity, this model will now override the
 generic model.  Outside that range, the generic model again takes over.
 The G4NeutronIsotopeProduction model depends on the G4NDL database so you
 must set the environment variable G4NEUTRONHPDATA to point to it.

 A similar procedure must be followed for each low energy parameterized
 model you wish to enable for isotope production, for example
       G4LENeutronInelastic
       G4LEProtonInelastic
       G4LEPionPlusInelastic
       ...
       ...

 Currently Geant4 provides only one detailed isotope production model that
 applies to incident neutrons, as well as a prototype for protons.  Others
 must be developed by users. 


 Stepping Action
 ---------------

 The user's SteppingAction must also be modified to include the headers

   #include "G4IsoParticleChange.hh"
   #include "G4InelasticInteraction.hh"

 and to add some output lines to 
 void MySteppingAction::UserSteppingAction(const G4Step* theStep).

 An example would be:

   G4String procName =
     theStep->GetPostStepPoint()->GetProcessDefinedStep()->GetProcessName();

   if (procName == "NeutronInelastic" || procName == "ProtonInelastic") {
     // Look only when neutron or proton initiated the isotope production

     G4IsoParticleChange* isotopeProdInfo =
             G4InelasticInteraction::GetIsotopeProductionInfo();
     if (isotopeProdInfo) {
       // Be sure that an isotope was created

       G4cout << " Production model: " << isotopeProdInfo->GetProducer() << G4endl;
       G4cout << " target nucleus (A,Z) : "
              << isotopeProdInfo-> GetMotherNucleus().GetA_asInt() << " , "
              << isotopeProdInfo-> GetMotherNucleus().GetZ_asInt() << G4endl; 
       G4cout << " produced isotope: " << isotopeProdInfo-> GetIsotope() << G4endl;
       G4cout << " production time: " << isotopeProdInfo->GetProductionTime() << G4endl;
       G4cout << " parent particle: " << isotopeProdInfo->GetParentParticle()->GetParticleName() 
     }
   }