Adding hadronic interaction

Physics Lists
1

Hello everyone

I am a very beginner user of Geant4 and this is my first post on the forum.
I received a ready-made macro to run the simulation.
However, it lacks the implementation of the hadronic interaction. I added the hadronic interaction in the PhysicsList.cc file.
My question is: where, apart from the PhysicsList.cc file, do I need to change the code so that the simulation takes into account the hadronic interaction?

Cheers
Rafal

2

I think PhysicsList.cc and PhysicsList.hh are enough to implement the hadronic interaction in the simulation.

1 Like
3

Thank you for your response !
But the simulation still does not take into account the hadronic interaction.
In the PhysicsList.hh file I added:

#include "G4HadronPhysicsQGSP_BIC.hh"
#include "G4HadronElasticPhysics.hh"
  and

void LiGenPhysicsList::ConstructProcess()
{
   AddTransportation();
   ConstructDecay();
   ConstructEM();
   ConstructOp();
  
   // Hadronic interaction
   G4HadronPhysicsQGSP_BIC* hadronPhysics = new G4HadronPhysicsQGSP_BIC();
   G4HadronElasticPhysics* elasticPhysics = new G4HadronElasticPhysics();
   hadronPhysics->RegisterMe(elasticPhysics);
   hadronPhysics->ConstructProcess();
}

in the file PhysicsList.hh

class LiGenPhysicsList : public G4VUserPhysicsList
{
public:

 //these methods Construct physics processes and register them
 void ConstructDecay();
 void ConstructEM();
 void ConstructOp();
 void ConstructHadron();// Hadronic constructor

}

4

An easy and direct way to do this is directly include FTFB_BERT in your main cc file. Here is the link for your reference (FTFP_BERT — Geant4 Documentation 11.2 documentation)
Example B5 has implemented it, you can check that one.

auto physicsList = new FTFP_BERT;
  physicsList->RegisterPhysics(new G4StepLimiterPhysics());
  runManager->SetUserInitialization(physicsList);
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5

Thank you.
When trying to run the simulation, an error occurred:

------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : had001
issued by : G4CrossSectionDataStore::BuildPhysicsTable
No cross section is registered for pi+

*** Fatal Exception *** core dump ***
**** Track information is not available at this moment
**** Step information is not available at this moment

-------- EEEE -------- G4Exception-END --------- EEEE -------

*** G4Exception: Aborting execution ***

6

Did you get this error after modifying the code as stated above ?

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7

My impression is that the hadronic physics data libraries are not set correctly. Or that particles are defined (e.g. pions) but no physics processes are instantiated. Could you please use a pre-built physics list of Geant4? e.g. QGSP_BIC_HP or any other one.

cheers
Susanna

1 Like
8

I haven’t added your code yet.
I add this code in PhysicsList.cc

void PhysicsList::ConstructHadron()
{
  auto particleIterator = GetParticleIterator();
  particleIterator->reset();
  while ((*particleIterator)()) {
    G4ParticleDefinition *particle = particleIterator->value();
    G4ProcessManager *pmanager = particle->GetProcessManager();
    G4String particleName = particle->GetParticleName();
    if (particleName == "pi+" || particleName == "pi-") {
      // hadron interaction for pion
      G4HadronInelasticProcess *inelasticProcess = new G4HadronInelasticProcess("inelastic", particle);
      pmanager->AddDiscreteProcess(inelasticProcess);
    }
  
  }
}

When compiling, there is no error message. The error appears only when starting the simulation (simPion.mac)

Cheers,
Rafal

9

Hi, did you instantiate the particles in the method ConstructParticle() of the Physics List?

cheers
Susanna

10

Hi, are you asking about this list?

void PhysicsList::ConstructParticle()
{
 
  G4BosonConstructor bConstructor;
  bConstructor.ConstructParticle();

  G4LeptonConstructor lConstructor;
  lConstructor.ConstructParticle();

  G4MesonConstructor mConstructor;
  mConstructor.ConstructParticle();

  G4BaryonConstructor rConstructor;
  rConstructor.ConstructParticle();

  G4IonConstructor iConstructor;
  iConstructor.ConstructParticle(); 
}

Cheers
Rafal

11

I suggest to use a pre-built physics list of Geant4, to see if you get the same error.

12

Please tell me where I can find this list?

13

https://geant4.web.cern.ch/ → Geant4 Documentation - Geant4 → Guide for Physics Lists — PhysicsListGuide 11.2 documentation → QGSP_BIC — PhysicsListGuide 11.2 documentation

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15

Deepachoudhary, I just added the code snippet from exampleB5.cc you mentioned to main cc. But the error message remains the same.

auto physicsList = new FTFP_BERT;
  physicsList->RegisterPhysics(new G4StepLimiterPhysics());
  runManager->SetUserInitialization(physicsList);
16

Guatelli and Mkelsey, thank you.
I added libraries (pions)

#include "G4HadronInelasticProcess.hh" 
#include "G4HadronPhysicsQGSP_BERT.hh"
#include "G4BGGPionInelasticXS.hh"
#include "G4BGGPionElasticXS.hh"
#include "G4PionPlus.hh"
#include "G4PionMinus.hh"
#include "G4HadronElasticProcess.hh"
#include "G4HadronElastic.hh"
#include "G4HadronElasticDataSet.hh"
#include "G4PiNuclearCrossSection.hh"
#include "G4ParticleTable.hh"
#include "G4HadronElasticPhysics.hh"
#include "G4HadronElastic.hh"

Is there any sample code for hadronic processes for pions available somewhere so I can see what it looks like?

17

Why are you doing this all by hand, rather than using one of the Geant4 reference physics lists?

18

Thank you very much. I think I understand what this list is about now. I added it to simPion.mac
/physics_list/select QGSP_BIC
before /run/initialize.
When I run the simulation I now get an error message:

/physics_list/select QGSP_BIC
***** COMMAND NOT FOUND </physics_list/select QGSP_BIC> *****

***** Batch is interrupted!! *****

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception: UIMAN0123
issued by: G4UImanager::ApplyCommand
Command aborted (100)
Error code : 100
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

I have to use Geant4 10.7.4 because only this version is compatible with my macro. Why the command
/physics_list/select QGSP_BIC is not correct?

19

Those macro commands (/physics_list/...) are associated with the G4PhysListFactory. In your main(), instantiate the factory:

   G4PhysListFactory thePLFactory;

You can choose a physics list in the code, as well as via the macro command:

  G4VModularPhysicsList* pl = thePLFactory->GetReferencePhysicsList("QGSP_BIC");
  rm->SetUserInitialization(pl);
20

Thank you very much. I added this code in main cc.

G4PhysListFactory thePLFactory;
    G4VModularPhysicsList* pl = thePLFactory.GetReferencePhysList("QGSP_BIC");
    runManager->SetUserInitialization(pl);

but the message will be the same.
I had to replace GetReferencePhysicsList with GetReferencePhysList.
Maybe this command is not supported in Geant4 10.7.4?

Cheers,
Rafal

21

It looks like it isn’t (my mistake in reading your earlier message). I had to go to the Geant4 sources to find out. In G4 10.7, the G4PhysListFactoryMessenger class creates a “/physics_lists/” directory (note the plural), which does not include commands to select a physics list at run time.

I cannot find a /physics_list/... command directory anywhere in the G4 source, not in G4 10.* nor in G4 11.*. Did you get that from one of the Geant4 examples?

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