Hi!
It seems there is an anomalous energy deposition for ions in G4EmStandardPhysics_option4 and option3.
Some strange continuous tail is added for about 30% of events, which lead to energy deposition larger than total kinetic energy of incoming ion. See pictures attached for option4 and option0.
This can be reproduced with TestEm1, macro attached. Switch between physics lists to reproduce.
energy_loss_test.txt (441 Bytes)
It seems to happen with almost all ions - I tested about 5, all had some artifacts in energy deposition, except 1 MeV 206Pb. But when I increased its energy to 12 MeV, the tail was added.
I saw it in 11.4.0, updated to 11.4.2 and saw the same thing.
The problem seems to be connected to G4NuclearStopping. I see the same anomalous tail if I use it in my user-defined physics list.
This is energy deposition spectrum for 1 MeV 16O with option4:
This is energy deposition spectrum for 1 MeV 16O with option0 (G4EmStandardPhysics()):
Geant4 Version: 11.4.2
Operating System: Ubuntu 26.04