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Question Physics list problem? inelastic gamma rays (n, n'gamma) are missing 

Forum: Physics List
Date: 26 Nov, 2013
From: John McFee <John McFee>


I'm running a simple Geant4 (4.9.6.p02) 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;
			G4NeutronHPElasticData * theNeutronData = new G4NeutronHPElasticData;

			// inelastic scattering
			G4NeutronInelasticProcess* theInelasticProcess =new G4NeutronInelasticProcess("inelastic");
			G4LENeutronInelastic* theInelasticModel = new G4LENeutronInelastic;
			G4NeutronHPInelastic * theLENeutronInelasticModel =new G4NeutronHPInelastic;
			G4NeutronHPInelasticData * theNeutronData1 = new G4NeutronHPInelasticData;

			// capture
			G4HadronCaptureProcess* theCaptureProcess =new G4HadronCaptureProcess;
			G4LCapture* theCaptureModel = new G4LCapture;
			G4NeutronHPCapture * theLENeutronCaptureModel = new G4NeutronHPCapture;
			G4NeutronHPCaptureData * theNeutronData3 = new G4NeutronHPCaptureData;

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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1 Idea: Re: Physics list problem? inelastic gamma rays (n, n'gamma) are missing   (Vladimir Ivanchenko - 27 Nov, 2013)
(_ More: Re: Physics list problem? inelastic gamma rays (n, n'gamma) are missing   (John McFee - 27 Nov, 2013)
(_ Idea: Re: Physics list problem? inelastic gamma rays (n, n'gamma) are missing   (Vladimir Ivanchenko - 13 Dec, 2013)
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