|Message: inelastic gamma rays (n, n'gamma) are missing||Not Logged In (login)|
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Hi, I'm running a simple Geant4 simulation to look at gamma rays from a target illuminated by 14MeV neutrons. The geometry is extremely simple with a monoenergetic neutron gun and a block target of material 30cm away embedded in a half space of another material. The problem I'm having is that I can see the thermal capture gamma rays (n, gamma) but not the inelastic gamma rays (n, n'gamma) for a variety of materials. For example, using an elemental C12 target in vacuum, I get 4.9465, 4.9463, 3.6840, 1.2625 MeV gammas (about 8000 total per 250,000,000 source neutrons) which are all due to 12C(n,gamma)13C but I do not see a single 4.443 MeV from 12C(n,n'gamma), even though the latter cross section is about 50 times the former. Other materials (e.g., O-16, N-14) give the same result (thermal captures but no inelastic gammas). Below is the relevant portion of the Physics list for neutrons that I have used. In my main program, I have invoked the QGSP_BERT_HP reference physics list (although I have also tried the QGSP_BIC_HP physics list with the same results). runManager->SetUserInitialization(new QGSP_BERT_HP); I then construct the following processes for neutrons: G4HadronElasticProcess* theNeutronElasticProcess = new G4HadronElasticProcess; G4LElastic* theElasticModel1 = new G4LElastic; G4NeutronHPElastic * theElasticNeutron = new G4NeutronHPElastic; theNeutronElasticProcess->RegisterMe(theElasticModel1); theElasticModel1->SetMinEnergy(19*MeV); theNeutronElasticProcess->RegisterMe(theElasticNeutron); G4NeutronHPElasticData * theNeutronData = new G4NeutronHPElasticData; theNeutronElasticProcess->AddDataSet(theNeutronData); pmanager->AddDiscreteProcess(theNeutronElasticProcess); // inelastic scattering G4NeutronInelasticProcess* theInelasticProcess =new G4NeutronInelasticProcess("inelastic"); G4LENeutronInelastic* theInelasticModel = new G4LENeutronInelastic; theInelasticModel->SetMinEnergy(19*MeV); theInelasticProcess->RegisterMe(theInelasticModel); G4NeutronHPInelastic * theLENeutronInelasticModel =new G4NeutronHPInelastic; theInelasticProcess->RegisterMe(theLENeutronInelasticModel); G4NeutronHPInelasticData * theNeutronData1 = new G4NeutronHPInelasticData; theInelasticProcess->AddDataSet(theNeutronData1); pmanager->AddDiscreteProcess(theInelasticProcess); // capture G4HadronCaptureProcess* theCaptureProcess =new G4HadronCaptureProcess; G4LCapture* theCaptureModel = new G4LCapture; theCaptureModel->SetMinEnergy(19*MeV); theCaptureProcess->RegisterMe(theCaptureModel); G4NeutronHPCapture * theLENeutronCaptureModel = new G4NeutronHPCapture; theCaptureProcess->RegisterMe(theLENeutronCaptureModel); G4NeutronHPCaptureData * theNeutronData3 = new G4NeutronHPCaptureData; theCaptureProcess->AddDataSet(theNeutronData3); pmanager->AddDiscreteProcess(theCaptureProcess); Is there something obvious that I'm missing that I have to invoke to turn on the inelastic neutron scattered gammas?
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