Query Regarding Positronium in Geant4

Particles, Track, Event, Run and Biasing
1

I am currently working on a Geant4 simulation involving positronium decay, specifically for modeling ortho-positronium annihilation into three gamma photons within a cylindrical detector geometry.

I would like to ask:
In the latest version of Geant4, is positronium (both para- and ortho-) defined as a particle in the Geant4 particle table or included in any standard physics list?
If so, could you kindly point me to the relevant class or documentation where it’s defined?

If positronium is not included natively, I would also appreciate any recommendations on how best to simulate its formation and decay — particularly for modeling its annihilation dynamics (e.g., angular correlations, lifetimes, decay channels).

Thank you in advance for your help.
Aditi Sati

2

Hello,

You can find the definition for all particles in source/particles, but it looks like positronium is not defined as of 11.3.1

A good place to start will be that directory to see how particles are constructed in Geant4 and the book for application developers section 3.3.2 which shows how to create custom ones. In addition the monopole and dmparticle examples in examples/extended/exoticphysics might also help.

3

Thank you for the response!