Proton Proton Collision in Geant4

Applications
1

I tried all night to create two particle guns shooting protons toward each other at the center of my detector. But they simply pass each other. I hoped to collide and create a secondary particle that my detector could track.

1)Is the generation of secondary particles after colliding two protons possible in geant4?

Also, I have used Pythia to create particle-particle collisions, I do have the root file containing their momentum and id. Maybe I can use that file as my particle generator, but what good can I get from using that in my geant4 simulation? As I already know the particle and the momentum.

2)It would be better if I could generate particle collision in geant4 and compare its result using my detector with the one of Pythia?

And if the collision and generation of secondary particle is possible in geant4 ? Is there any code available online.

2

Tracks do not ever interact in Geant4. Period. Geant4 processes one single track through your material geometry, computing all of the interactions with the material, creating secondaries, etc. When that track ends (decays, loses all it’s initial energy, leaves the world volume), Geant4 starts processing the next track in its list. And so on until there are no tracks left to process.

If you want to simulate particle-particle collisions, then you need to use an event generator like Pythia. It does have an API, so you can link it into your Geant4-based user application, call Pythia from your PrimaryGeneratorAction, and register the particles Pythia produces as your primaries.