Moving radioactive ion question


I’m working on an application which requires a gamma-ray photon to be emitted a short time (tau ~ 5 ps) after the primary ion has alpha decayed.

If I use the standard Radioactive Decay models in Geant4 the gamma rays are emitted once the recoiling nuclei have stopped moving. However, the application is looking to study the Doppler shift of the photon energy as a function of recoil velocity.

Does anyone know of any plans by the Geant4 community to include secondary radioactive decays in moving particles? Also, does anyone have any advice (examples) they could share on how to create this with the particle gun?

Thanks for your time.