Hi, I didn't find a matching/connected issue. But I am not very familiar with Geant4, so sorry if I misunderstood them. I am trying to send a fixed nr of particles, with random properties(energy / momentum), using the G4ParticleGun class. In my user class that inherits from G4VUserPrimaryGeneratorAction I am doing: G4int n_particle = 1; beam = new G4ParticleGun(n_particle); G4ParticleTable *particle_table = G4ParticleTable::GetParticleTable(); G4ParticleDefinition *electron = particle_table->FindParticle("e-"); beam->SetParticleDefinition(electron); And this leads to the generation of a nr of primary electrons that corresponds to the nr of events that I set in my main function through: runManager->BeamOn(in.nevents); However, when I start specifying the properties of each particle, for example with the line below: beam->SetParticleMomentumDirection(G4ThreeVector(0.,0.,1.)); I get many more primary particles than the number of events (and they don't vary linearly, for low number of events). I was wondering if there is a way for me to send the same nr of particles as the nr of events (i.e. only one primary particle per event), but with specific properties. Thank you, Diana
Just as an update, if I add the line below: beam->SetParticleEnergy(rand_n[0]); To the initially working section described in the previous message, I still get the correct number of primary particles. But if I also add: beam->SetParticlePosition(G4ThreeVector( rand_n[1],rand_n[2],rand_n[3])); Then the number of primary particles seems random. I think I might not be understanding what position and momentum settings are supposed to do according to the G4ParticleGun class. But I read their definition and still can't figure out how to make them not introduce additional primary particles.
You may want to consult to one of our examples that demonstrate the use of UserPrimaryGeneratorAction. For example, https://geant4.kek.jp/lxr/source/examples/basic/B3/B3a/src/B3PrimaryGeneratorAction.cc For further questions, please use our discussion forum https://geant4-forum.web.cern.ch
Thank you very much for your reply. I tried to follow exactly that example. And I noticed that changing the momentum direction from (1.0,0.0,0.0) to (0.0,0.0,1.0) led to the generation of additional primary particles (instead of the same nr as the nr of events). So I corrected that direction in my code. But, whenever I specify the random position, just as in the example, I get additional primary particles being created. Do you have any suggestions on how I can find the source of this issue? Thank you very much for your support, Diana
