|Message: Re: low energy deuteron propagation||Not Logged In (login)|
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On Tue, 30 Oct 2007, Abigail Bickley wrote: > *** Discussion title: Physics List > Email replies to PublicHyperNews@slac.stanford.edu must include: > In-Reply-To: <"/phys-list/424"@geant4-hn.slac.stanford.edu> > Subject: ...change this to be about your reply. > > Dear Experts, > > I am trying to simulate the propagation of a 300keV deuteron in a gas > filled volume. Simple range calculations tell me that the track length > should be approximately 10cm. However I find that in Geant the tracks > are only ~2cm long. Is geant capable of reproducing the interactions > of a deuteron of this energy in a gas? I've included some specific > details below. Suggestions would be appreciated. > > Thank you for your advice, > > Abby > Sorry, this Physics Lists is completely incorrect: 1) two processes of ionisation are included simulteneusly, ionisation is at least doubles. 2) standard and low-energy hadron ionisation cannot be used in the same Phsyics Lists Would suggest to use Physics Lists from EM examples, for example: $G4INSTALL/examples/extended/electromagnetic/TestEm7 VI > Physics Processes in PhysicsList: > pmanager->AddProcess(new G4MultipleScattering,-1, 1, 1); > pmanager->AddProcess(new G4hIonisation, -1, 2, 2); > G4double demax = 0.05; > G4double stmin = 1.e-9 * m; > G4hLowEnergyIonisation* lowEIonisation = new G4hLowEnergyIonisation(); > pmanager->AddProcess( lowEIonisation, -1,3,3); > lowEIonisation->SetStepFunction( demax, stmin ); > *Is there a threshold cut being applied that is inappropriate? > > Definition of gas in DetectorConstruction: > //TPCgas_D2 is 100% D2 > G4Element* D = new G4Element("Deuterium","D", z= 2., a= 2.0141*g/mole); > G4Material* TPCgas_D2 = new G4Material("TPC_gas_D2",0.036*mg/cm3,1); //0.2atm density > TPCgas_D2->AddElement(D,2); > *changing gas density has expected effect on particle path length; > *since the particle is created in the gas volume it never interacts > with any other material > > Definition of deuteron in PrimaryEventGenerator: > G4ParticleDefinition* particle = particleTable->FindParticle("deuteron"); > particleGun->SetParticleDefinition(particle); > energy = 0.3*MeV; > p_z= G4UniformRand()*energy; > p_x = G4UniformRand()*(energy-p_z); > p_y = sqrt(energy*energy-p_x*p_x-p_z*p_z); > particleGun->SetParticleEnergy(energy); > particleGun->SetParticleMomentumDirection(G4ThreeVector(p_x,p_y,p_z)); > particleGun->GeneratePrimaryVertex(anEvent); > *perhaps energy is per nucleon? (but doubling it doesn't solve the problem) > *perhaps this is total energy not kinetic energy? > > -- Vladimir Ivanchenko ### CERN PH SFT Tel: +41-22-76-78-871 Vladimir.Ivantchenko@cern.ch ###
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