All you want to know about GEANT4 simulations…

I am starting to study the use of GEANT4 in MFT. However, I found that we can run the simulation in two ways:

  • o2-sim-serial -m MFT -e TGeant3 -g fwmugen -n 1
  • o2-sim-serial -m MFT -e TGeant4 -g fwmugen -n 1

My question is, can anyone tell me what is the difference between using Geant3 and Geant4 in O2 simulations?

On the other hand, I contacted a Geant4 expert, Dennis Wrigth, and asked:

Could you tell me what are the main differences between using Geant3 and Geant4?

Answer from Dennis:
Hi Luis,
Geant3 is the old Geant, written in Fortran and having rather primitive hadronic physics. The geometry and EM physics are not bad,
but there has been no update or development of Geant3 since about 2000.
Geant4 is written in C++ and is object-oriented and multithreaded. The geometry and physics (both EM and hadronic) have been
greatly improved since 2000 and it is under constant development and testing by the Geant4 collaboration.