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Question Follow up questions on Liquid Hydrogen 

Forum: Geometry
Date: 31 May, 2011
From: Evan Askanazi <Evan Askanazi>

So i was informed that geant4 does not have mechanisms for separating para and ortho hydrogen. In that case, there were some things I was wondering about. Since I am working on the npdgamma experiment at oakridge I need help in determining the validity of Geant4 in determining neutron scatter and capture and so I was wondering about some aspects of Liquid Hydrogen in geant4.

So lets say I have Liquid Hydorgen defined as follows :

 G4Material* H2 = new G4Material("H2Liquid",density= 67.8*mg/cm3 , ncomponents=1,kStateLiquid, temperature = 20*kelvin,pressure =1.*atmosphere );
  H2->AddElement(H, natoms = 2);

With element H naturally defined as

 G4Element* H  = new G4Element("Hydrogen",symbol="H",  z= 1, a=   1.01*g/mole);

Then the H2Liquid would by default be 75 percent ortho and 25 percent parahydorgen. Is that correct or does geant4 use a different ratio depending on temperature.

Also, I was using these Physics Lists :

G4HadronElasticProcess* theNeutronElasticProcess = new G4HadronElasticProcess();
   G4NeutronHPElastic* theHPElasticModel = new G4NeutronHPElastic();
   G4NeutronHPElasticData* theHPElasticData = new G4NeutronHPElasticData();
   //   theNeutronElasticProcess ->SetMaxEnergy ( 4.0*MeV );
     theNeutronElasticProcess->RegisterMe(theHPElasticModel);
        theNeutronElasticProcess->AddDataSet(theHPElasticData);

G4NeutronInelasticProcess* neutronInelasticProcess = new G4NeutronInelasticProcess("inelastic-neutron");
   G4NeutronHPInelastic* theHPInelasticModel = new G4NeutronHPInelastic();
   G4NeutronHPInelasticData* neutronHPInelasticCrossSection =new G4NeutronHPInelasticData();
   neutronInelasticProcess->RegisterMe(theHPInelasticModel);
   neutronInelasticProcess->AddDataSet(neutronHPInelasticCrossSection);

G4HadronFissionProcess* neutronFissionProcess = new G4HadronFissionProcess("fission-neutron");
   G4NeutronHPFission* neutronHPFissionModel = new G4NeutronHPFission();
   G4NeutronHPFissionData* neutronHPFissionCrossSection = new G4NeutronHPFissionData();
   neutronFissionProcess->RegisterMe(neutronHPFissionModel);
   neutronFissionProcess->AddDataSet(neutronHPFissionCrossSection);

G4HadronCaptureProcess* neutronCaptureProcess = new G4HadronCaptureProcess("capture-neutron");
   G4NeutronHPCapture* neutronHPCaptureModel = new G4NeutronHPCapture();
   G4NeutronHPCaptureData* neutronHPCaptureCrossSection = new G4NeutronHPCaptureData();
   neutronCaptureProcess->RegisterMe(neutronHPCaptureModel);
   neutronCaptureProcess->AddDataSet(neutronHPCaptureCrossSection);

G4NeutronHPThermalScattering* theNeutronThermalElasticModel = new G4NeutronHPThermalScattering();

G4NeutronHPThermalScatteringData* theHPThermalScatteringData = new G4NeutronHPThermalScatteringData();

theNeutronThermalElasticModel->SetMaxEnergy ( 4.0*eV ); //theNeutronElasticProcess->RegisterMe(theNeutronThermalElasticModel); //theNeutronElasticProcess->AddDataSet(theHPThermalScatteringData);

pManager->AddDiscreteProcess(theNeutronElasticProcess);
    pManager->AddDiscreteProcess(neutronInelasticProcess);
      pManager->AddDiscreteProcess(neutronCaptureProcess);
   pManager->AddDiscreteProcess(neutronFissionProcess);
      pManager->DumpInfo();

Right now I use G4HadronElasticProcess instead of G4NeutronHPThermalScattering. I am launching 10000 neutrons into a large block of Liquid Hydrogen and observing the extent that the neutrons scatter. I had presumed that G4HadronElasticProcess was capable of handling this process with reasonable accuracy presuming that the geant4 hydrogen is 3:1 ortho:para. Is Geant4 capable of doing this ?

Thanks again for your help

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1 Feedback: Re: Follow up questions on Liquid Hydrogen   (Gabriele Cosmo - 22 Jun, 2011)
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