Explanations / documentation of G4 functions

Getting Started
1

Hi,

I’m creating my first project in Geant4 and I used to be used to ROOT but it’s a while back then. However, when looking for the meaning of specific functions like G4PVPlacement ( Geant4: G4PVPlacement Class Reference , is this the correct official adress?) I miss an explanation of the meaning of the function itself and its parameters as well. E.g., what is it doing in general and in specific when I tune the parameters?
Is it possible to read such things up somewhere?

2

https://geant4-userdoc.web.cern.ch/UsersGuides/ForApplicationDeveloper/html/Detector/detector.html

This is the documentation for the Geometry section of the Geant4 toolkit. If you want more in depth knowledge of what each function is doing, the entire source code can be found in the link you posted

3

Thank you!

To become more independent I could use some guidance. For example, at the moment I am looking which particle I’ve to use for x-rays, means, which particles are available? "
I know this command:

particleTable->FindParticle(“gamma”);

and I know, that e.g. “proton” is also working. But “photon” isn’t and “electron” isn’t, too. Where can I read up which particles are available?

edit: Meanwhile, I stumbled over Geant4 Particle List . Btw, x-rays are not gamma-particles but rather Bremsstrahlung. That’s why gamma is not helping imo, or is it representing all photons? Do I conclude correctly that there is no difference between gamma and opticalphoton?

4

Gamma rays, x-rays, and optical photons are all the same thing, photons. Not all X-rays from from Bremsstrahlung. An x-ray and a gamma ray of the same energy are the same thing, the distinction only comes in from their source, not how they behave on interacting with matter (which is what GEANT4 is simulating).

The only reason there is a difference between optical photons and gamma/xrays is because the way photons interact with materials depends on their energy, and optical photons act differently than high energy photons.

You can model optical photon processes (surface effects, reflections, refractions, scattering, etc) using an optical photon physics list

https://geant4-userdoc.web.cern.ch/UsersGuides/ForApplicationDeveloper/html/TrackingAndPhysics/physicsProcess.html#optical-photon-processes

1 Like
5

Alright, thanks a lot for the clarification.

Just for myself in the future. Where can I look up supported particles?

6 
/run/initialize
/particle/list
1 Like
7

Thanks a lot!
Isn’t there also any (official) website with these information?

8

The list of particles is dependent on your physics list. Some of the reference physics lists instantiate “every” particle that G4 supports, but others don’t.

1 Like
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