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Forum: Hadronic Processes
Re: None Why an Ion of H3 does not generate any secondary? (Jorge Cabello)
Date: 01 Dec, 2006
From: Vladimir IVANTCHENKO <vnivanch@mail.cern.ch>

On Fri, 1 Dec 2006, Jorge wrote:

> *** Discussion title: Hadronic Processes
> Email replies to PublicHyperNews@slac.stanford.edu must include:
>   In-Reply-To: <"/hadronprocess/604"@geant4-hn.slac.stanford.edu>
>   Subject: ...change this to be about your reply.
> 
> Hi there,
> 
> I have been simulating ions of C14(average energy 49keV) and S35
> (average energy 48-53 keV) with the GPS with no problem so far. These
> ions decay into 3 secondaries, 1 beta electron (the one that I am really
> interested), 1 anti_nu_e and 1 ion of another element.
> 
> The point is that now I have to do the same simulations with H3 or
> triton (average energy 5.7 keV) but the code does not generate
> absolutely any secondary.
> 
> I thought that it was because of the Cuts. I changed them in the Physics
> List:
> 
> void Exp2PhysicsList::SetCuts()
> {
>   defaultCutValue = 0.001*um;
>   SetCutsWithDefault();
> } 
> ... but no success. Then I read that these cuts are only applied to 
> EM processes and in this case, to use the GPS and GenericIons, I had
> to register the G4Decay process to the GenericIon. So these cuts 
> are not applied to this particle (correct me if I'm wrong).
> 
> Then I thought the it could be because I had to register the low energy
> processes for the electrons instead of the normal ones:
> 
> if (particleName == "e-") {    
>       //electron
>       /*pmanager->AddProcess(new G4MultipleScattering,-1, 1,1);
>       pmanager->AddProcess(new G4eIonisation,       -1, 2,2);
>       pmanager->AddProcess(new G4eBremsstrahlung,   -1, 3,3);*/
> 
>       loweIon  = new G4LowEnergyIonisation("LowEnergyIoni");
>       loweBrem = new G4LowEnergyBremsstrahlung("LowEnBrem");
>       loweBrem->SetAngularGenerator("tsai");
> 
>       pmanager->AddProcess(new G4MultipleScattering, -1, 1,1);
>       pmanager->AddProcess(loweIon,     -1, 2,2);
>       pmanager->AddProcess(loweBrem,    -1,3,3);
> }
> ... but no success.
> 
> I think that the secondaries are being killed somewhere in the code but
> I don't know where. If I only could find somewhere in the code where the
> secondaries are still alive and try to enable something to let them
> live, like the flag SetGoodForTrackingFlag or something like that.
> 
> Please, help me to keep these secondaries safe from the code. They have
> the right to live as well.
> 
> Thanks a lot.
> 

Hello,

Whe you so low energy incident ion, the delta-electrons are not emmited 
because of default cut limitation 1 keV. To allow to reduce the cut one 
has to add into SetCut method:

G4double lowlimit=1.*eV;  
G4ProductionCutsTable::GetProductionCutsTable()->SetEnergyRange(lowlimit,100*GeV);

After that, the low limit of cut value for delta-electron production by 
ions will be mean ionisation potential of the media.

Minor comment: if you want to use low-energy package, you need to change a 
line, the correct one is following:

pmanager->AddProcess(loweBrem,    -1,-3,3);

also "tsai" angular distribution is inadequate for 1-10 keV initial energy 
of electrons. If you do not care about precise angles of gamma - it is 
fine - "tsai" is much faster, but if you need correct angles then other 
angular distribution should be used.

VI

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1 None: Re: Why an Ion of H3 does not generate any secondary?   (Jorge - 01 Dec, 2006)
(_ None: Re: Why an Ion of H3 does not generate any secondary?   (Vladimir IVANTCHENKO - 01 Dec, 2006)
(_ None: Re: Why an Ion of H3 does not generate any secondary?   (Vladimir IVANTCHENKO - 01 Dec, 2006)
1 None: Re: Why an Ion of H3 does not generate any secondary?   (Jorge - 01 Dec, 2006)
3 None: Re: Why an Ion of H3 does not generate any secondary?   (Jorge - 05 Dec, 2006)
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