Need help calculating U-235 fission cross-section for neutrons

Physics Processes, Models and Cross Sections
1

Geant4 Version: 11.2.1
Operating System: Ubuntu 22.04.4 LTS
CMake Version: 3.26.3

Hello everyone,

I’m currently working with the Hadronic extended example (Hadr04), which utilizes the NeutronHP physics. I’m trying to calculate or retrieve the fission cross-section for uranium-235 (U-235) when interacting with neutrons.

file NeutronHPphysics.cc :


#include "NeutronHPphysics.hh"

#include "G4GenericMessenger.hh"

#include "G4ParticleDefinition.hh"
#include "G4ProcessManager.hh"
#include "G4ProcessTable.hh"

// Processes

#include "G4HadronElasticProcess.hh"
#include "G4ParticleHPElasticData.hh"
#include "G4ParticleHPThermalScatteringData.hh"
#include "G4ParticleHPElastic.hh"
#include "G4ParticleHPThermalScattering.hh"

#include "G4HadronInelasticProcess.hh"
#include "G4ParticleHPInelasticData.hh"
#include "G4ParticleHPInelastic.hh"

#include "G4NeutronCaptureProcess.hh"
#include "G4ParticleHPCaptureData.hh"
#include "G4ParticleHPCapture.hh"

#include "G4NeutronFissionProcess.hh"
#include "G4ParticleHPFissionData.hh"
#include "G4ParticleHPFission.hh"

#include "G4SystemOfUnits.hh"

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

NeutronHPphysics::NeutronHPphysics(const G4String& name)
: G4VPhysicsConstructor(name)
{
  // define commands for this class
  DefineCommands();  
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

NeutronHPphysics::~NeutronHPphysics()
{
  delete fMessenger;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

void NeutronHPphysics::ConstructProcess()
{
  G4ParticleDefinition* neutron = G4Neutron::Neutron();
  G4ProcessManager* pManager = neutron->GetProcessManager();
   
  // delete all neutron processes if already registered
  //
  G4VProcess* process = 0;
  process = pManager->GetProcess("hadElastic");
  if (process) pManager->RemoveProcess(process);
  //
  process = pManager->GetProcess("neutronInelastic");
  if (process) pManager->RemoveProcess(process);
  //
  process = pManager->GetProcess("nCapture");      
  if (process) pManager->RemoveProcess(process);
  //
  process = pManager->GetProcess("nFission");      
  if (process) pManager->RemoveProcess(process);      
         
  // (re) create process: elastic
  //
  G4HadronElasticProcess* process1 = new G4HadronElasticProcess();
  pManager->AddDiscreteProcess(process1);
  //
  // model1a
  G4ParticleHPElastic*  model1a = new G4ParticleHPElastic();
  process1->RegisterMe(model1a);
  process1->AddDataSet(new G4ParticleHPElasticData());
  //
  // model1b
  if (fThermal) {
    model1a->SetMinEnergy(4*eV);   
   G4ParticleHPThermalScattering* model1b = new G4ParticleHPThermalScattering();
    process1->RegisterMe(model1b);
    process1->AddDataSet(new G4ParticleHPThermalScatteringData());
  }
   
  // (re) create process: inelastic
  //
  G4HadronInelasticProcess* process2 =
    new G4HadronInelasticProcess( "neutronInelastic", G4Neutron::Definition() );
  pManager->AddDiscreteProcess(process2);   
  //
  // cross section data set
  G4ParticleHPInelasticData* dataSet2 = new G4ParticleHPInelasticData();
  process2->AddDataSet(dataSet2);                               
  //
  // models
  G4ParticleHPInelastic* model2 = new G4ParticleHPInelastic();
  process2->RegisterMe(model2);    

  // (re) create process: nCapture   
  //
  G4NeutronCaptureProcess* process3 = new G4NeutronCaptureProcess();
  pManager->AddDiscreteProcess(process3);    
  //
  // cross section data set
  G4ParticleHPCaptureData* dataSet3 = new G4ParticleHPCaptureData();
  process3->AddDataSet(dataSet3);
  //
  // models
  G4ParticleHPCapture* model3 = new G4ParticleHPCapture();
  process3->RegisterMe(model3);
   
  // (re) create process: nFission   
  //
  G4NeutronFissionProcess* process4 = new G4NeutronFissionProcess();
  pManager->AddDiscreteProcess(process4);
  //
  // cross section data set
  G4ParticleHPFissionData* dataSet4 = new G4ParticleHPFissionData();
  process4->AddDataSet(dataSet4);                               
  //
  // models
  G4ParticleHPFission* model4 = new G4ParticleHPFission();
  process4->RegisterMe(model4);
  


}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

void NeutronHPphysics::DefineCommands()
{
  // Define /testhadr/phys command directory using generic messenger class
  fMessenger = new G4GenericMessenger(this,
                        "/testhadr/phys/",
                        "physics list commands");

  // thermal scattering command
  auto& thermalCmd
    = fMessenger->DeclareProperty("thermalScattering", fThermal);

  thermalCmd.SetGuidance("set thermal scattering model");
  thermalCmd.SetParameterName("thermal", false);
  thermalCmd.SetStates(G4State_PreInit);  
}

Could someone please provide guidance or a code snippet ?

Any help or insights would be greatly appreciated!

Thank you,

Ayoub

2

start with Hadr03 and nFission.mac

3

Ok, Thanks for the starting point!