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Forum: Hadronic Processes
Re: None Neutron elastic process (Liang Zhan)
Date: 05 Mar, 2007
From: Vladimir IVANTCHENKO <vnivanch@mail.cern.ch>

On Mon, 5 Mar 2007, Liang Zhan wrote:

> *** Discussion title: Hadronic Processes
> Email replies to PublicHyperNews@slac.stanford.edu must include:
>   In-Reply-To: <"/hadronprocess/664"@geant4-hn.slac.stanford.edu>
>   Subject: ...change this to be about your reply.
> 
> Hi all,
> 
> I am simulating neutron transportion in water and neutron captured in
> liquid scintillator. I care about neutrons with energy between 0-500MeV.
> I constructed the neutron elastic process as following:
> 
>       G4HadronElasticProcess* theHadronElasticProcess = new G4HadronElasticProcess();
>       G4LElastic* theNeutronLElastic = new G4LElastic();
>       G4NeutronHPElastic* theNeutronHPElastic = new G4NeutronHPElastic();
>       theNeutronHPElastic->SetMaxEnergy( 20.*MeV );
>       theNeutronLElastic->SetMinEnergy( 20.*MeV );
>       theNeutronLElastic->SetMaxEnergy( 1200.*GeV );
> 
>       // The G4LEnp may be better than G4LElastic for n+p elastic process.
>       // The G4LElastic has probability of killing neutron in n+p elastic process
>       // therefore the neutron thermalization process can not be simulated 
>       // >20MeV neutron.
> 
>       theNeutronLElastic->SetMaxEnergy( 0.*MeV, G4Element::GetElement("Hydrogen"));
>       G4LEnp* theNPElastic = new G4LEnp();
>       theNPElastic->SetMinEnergy(0.*MeV);
>       theNPElastic->SetMaxEnergy(0.*MeV);
>       theNPElastic->SetMinEnergy(20.*MeV, G4Element::GetElement("Hydrogen"));
>       theNPElastic->SetMaxEnergy(20.*GeV, G4Element::GetElement("Hydrogen"));
>       theNPElastic->SetVerboseLevel(2);
>       theHadronElasticProcess->RegisterMe( theNPElastic);
> 
>       theHadronElasticProcess->RegisterMe( theNeutronHPElastic );
>       theHadronElasticProcess->RegisterMe( theNeutronLElastic );
>       AddDataSet(theHadronElasticProcess, new G4NeutronHPElasticData() );
>       pmanager->AddDiscreteProcess( theHadronElasticProcess );
> 
> Below 20MeV G4NeutronHPElastic is invoked. Above 20MeV G4LElastic is
> used except for n+p scattering because I found that G4LElastic process
> may kill the neutron in n+p scattering and it is impossible for a
> neutron to thermalize Therefore I used G4LEnp for n+p scattering above
> 20MeV.
> 
> But it was out of expect that the G4LEnp was invoked in the neutron and
> oxygen scattering. Here is the output of simulation of 30MeV neutron
> transport in water,
> 
> ***********************************************************************************
> * G4Track Information:   Particle = neutron,   Track ID = 1,   Parent ID = 0
> *********************************************************************************************************
> 
> Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
>     0        0        0        0        30        0        0         0       water initStep
> G4LEnp:ApplyYourself: incident particle: neutron
> P = 0.2393197396789492 GeV/c, Px = -6.55725473919233e-18 GeV/c, Py = 8.569533971325427e-19 GeV/c, Pz = 0.2393197396789492 GeV/c
> E = 0.9695656300000001 GeV, kinetic energy = 0.03 GeV, mass = 0.93956563 GeV, charge = 0
> G4LEnp:ApplyYourself: material:
> A = 16, Z = 8, atomic mass 0.9382722999999999GeV
> G4LEnp:ApplyYourself: total:
> E = 1.90783793 GeV, mass = 1.892768245017515 GeV, charge = 8
> ... ...
>     1    -10.6     1.75    -1.92         0        0     10.9      10.9       water LElastic
> 
> And I have two questions.
> 1. Is G4LEnp can be used for n+p scattering instead of G4LElastic? Is there
>    any other way to simulate n+p scattering
> 2. How to use G4LEnp properly? How to avoid G4LEnp invokation in neutron and oxygen scattering?
> 
> Thanks.
> 
> Liang Zhan.
>

Hello,

It seems we have better solution for today. Please, have a look into 
example/extended/hadronic/Hadr01

Try to choose QGSP_BIC_HP PhysicsList.

VI 

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