Getting charge in G4_Galactic from a neutral heavy ion beam

Physics Processes, Models and Cross Sections
1

Please fill out the following information to help in answering your question, and also see tips for posting code snippets. If you don’t provide this information it will take more time to help with your problem!

_Geant4 Version:_11.2.1
_Operating System:_linux
_Compiler/Version:_g++ 13.1.1
_CMake Version:_3.26.4

I am playing with beam transport in G4_Galatic of heavy nuclei (Tb up to Am beam). I define the transport part of my setup as G4_Galatic and set the beam energy and charge using gps as such

/gps/particle ion
/gps/ion 95 243 0 0
/gps/pos/type Beam
/gps/pos/centre 0 5. -685.5 mm
/gps/pos/sigma_x 2.0 mm
/gps/pos/sigma_y 2.0 mm
/gps/direction 0 0 1
/gps/ene/type Gauss
/gps/ene/mono 104 MeV
/gps/ene/sigma 3.9 MeV

however i get a charge of around 7 even with a neutral beam input. When i disable the ionizing process i get the correct charge but then i lose the energy in my detector setup at the end of the transport line.

Is there is a way to disable the ionizing process in vacuum or in specific volume?

2

I do not see zero density vacuum as reasonable. The G4_Galactic material is not empty vacuum, it is something still per cm3. It is the best vacuum you can have in the Universe. Anywhere on Earth, you get way denser gases called vacuum. The observed charge will make sense in an existing environment.