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The proper place for posting your query is the "Hadronic Processes" forum. Please, do so if not done already. Thanks. Gabriele ---------------- On Tue, 31 May 2011 18:24:01 GMT, Evan Askanazi wrote: > 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 >