Re: Ions

 Hi Dmitry,

 Your problem with the Alpha particle is now  fixed in the development version of Geant4 VMC.  Check, please, if it is ok on your side, too.

> correct way to create ion as a beam particle? If I pass say iron as an ion
> then it works (because this particle is not defined in G4 seems), but there
> are no hadronic interactions. Perhaps you could advise me how to set them up

 If you are using the default Geant4 VMC physics list,  hadronic interactions are not activated by default.  You can activate them via the TG4PhysicsListOptions  in a similar way as it is demonstrated in E06 for  optical processess (see E06/g4Config.C).  But it will be better to choose an appropriate physics list  provided by Geant4 and include it as it is demonstrated  in the E03 example.

 Best regards,

 Ivana

-- 
==============================================================
e-mail:  Ivana.Hrivnacova_at_cern.ch
address: Institut Physique Nucleaire, 91406 Orsay, France
phone:   (33) 01 69 15 65 94
==============================================================


On Tue, 12 Sep 2006, Dmitry Naumov wrote:



> Dear VMC team,

> 

> I am experiencing a problem with ions as beam particles. Perhaps I do not

> understand  how to make them properly. This is what I am doing:

> 

> TString fParticleName reads from configuration type of the particle. Then I

> check:

> 

>    if (!(fParticleName.Contains("proton") ||

> fParticleName.Contains("neutron"))) {

>        TParticlePDG *part =

> TDatabasePDG::Instance()->GetParticle(fParticleName);

>        if (part)

>            fPdg = part->PdgCode();

>        else {

>            cout << "DEFINE ION MYSELF!!! " << endl;

> gMC->DefineIon(fParticleName.Data(),fZ,fA,fQ,fExcEnergy);

>            fPdg =

> TDatabasePDG::Instance()->GetParticle(fParticleName)->PdgCode();

>        }

>        cout << fParticleName << " " << fPdg << " this particle is created " <<

> fZ << " " << fA << " " << endl;

>    }

> 

> If particle with this name is already defined in TDatabasePDG then just get

> its Pdg code to pass into MCStack object as a primary. If not then add it

> using gMC->AddIon() method.

> I am calling this piece of code after

> 

>    gMC->Init();

>    gMC->BuildPhysics();

> 

> which should create all particles (if I am not wrong in this point).

> 

> Just before to call the above piece of code I check the TDatabasePDG and see

> that alpha etc are there:

> 

> Rootino                    0    Mass:   0.0000 Width (GeV): Stable

> Charge:   0.0

> Deuteron              10010020  Mass:   1.8711 Width (GeV): Stable

> Charge:   3.0

> Triton                10010030  Mass:   2.8094 Width (GeV): 1.6916e-33

> Charge:   3.0

> Alpha                 10020040  Mass:   3.7284 Width (GeV): Stable

> Charge:   6.0

> HE3                   10020030  Mass:   2.8094 Width (GeV): 0.0000e+00

> Charge:   6.0

> Cherenkov             50000050  Mass:   0.0000 Width (GeV): 0.0000e+00

> Charge:   0.0

> FeedbackPhoton        50000051  Mass:   0.0000 Width (GeV): 0.0000e+00

> Charge:   0.0

> Alpha                 10020040  Mass:   3.7284 Width (GeV): Stable

> Charge:   6.0

> 

> When my piece of code is done I see this:

> 

> Alpha 10020040 this particle is created 2 4

> 

> 

> 

> Finally I have the following exception:

> ### Run 0 start.

> Alpha  Alpha pdgEncoding: 10020040

> 

>    TG4PrimaryGeneratorAction::TransformPrimaries:

>    G4ParticleTable::FindParticle() failed.

> *** TG4Exception: Aborting execution ***

> 

> 

> Which happens in void TG4ParticlesManager::AddIon

> <http://ivana.home.cern.ch/ivana/g4vmc_html/classTG4ParticlesManager.html#1a536e

> f6d4af275048ff6ce95a2cf02b>

> 

> method. Could you please help me to understand what is wrong and what is the

> correct way to create ion as a beam particle? If I pass say iron as an ion

> then it works (because this particle is not defined in G4 seems), but there

> are no hadronic interactions. Perhaps you could advise me how to set them up

> also for this case? Thanks a lot, Dmitry

>