Dear Geant4 users,
I’m having an issue regarding the dose deposition of Helium 4 ions in water. My simulation consists in launching a pencil beam (so every particle at 0.0.0) made of He4 ions, fully ionized (so with 2+ charge), with a kinetic energy of 198 MeV, in a box of water. According to the NIST database, the expected range of 198 MeV He4 ions in water is around 22.2 mm. As 50 MeV protons have the same range in water, I also did the simulations with 50 MeV protons to compare both results. The Geant4 version I first used for the simulations was 10.7, and My Bragg peaks appeared at a smaller range than the expected value (see the green curve in the attached figure). However, when I update to Geant4 11.0 (red curve in the attached figure), I can see that the expected range is obtained and fits with the 50 MeV protons result (blue curve).
Did anyone have the same issue with geant4 10.7? I went through the 11.0 release notes but nothing is mentioned regarding the update of He4 ion’s physical processes. And I can’t understand how a version update can make such a massive difference in the range?
Any help would be very appreciated.