Back Scattered Electrons in Ions

Dear experts,

I am trying to simulate back scattered electrons by using Geant4.7.p02.

I have a beam of Pb54+ ( Energy = 4.2 MeV/nuc) colliding against a target of Stainless steal, and I am interested in the number of backscattered electrons.

When I set up a beam to be a beam of electrons of around 2.7 keV which is the energy I would expect the electrons on the ion to have I see some backscattered electrons. Nevertheless when I set the beam of 54+Pb I don’t see much happening, all the ions are stopped inmediatelly in the material, barelly no transport and no secondaries, nothing…

I am using FTFP_BERT as a physics list in both cases. Should I be using another physics list or modifiying any cut in order to be able to correctly simulate the lead particles?