Question about dose depth deposition at different energies

I obtain the following depth-dose deposition figures for heavy ion (calcium) incident on a Si-Ge block of 0.01 um and 10 um thickness respectively. Figures 1 and 2 are obtained for different incident energies. In fig 1, I would expect to see a Bragg peak before the energy deposition reduces to zero, as the interaction cross section increases when incident energy decreases. Such a curve is more obvious in fig 2 at 10 MeV.

Fig 1: 300 MeV heavy ion incident energy

Fig2: 10 MeV heavy ion incident energy

  1. Regarding fig 1, is it mandatory to see a Bragg peak in such interactions?

  2. How can I best explain fig 1. from a particle physics context? Is the idea simply that at higher energy, the interaction cross section is smaller, and therefore there is energy deposition is more uniform?

The physics lists used are the standard em physics and livermore. I am working on a modified version of extended example TestEm11. Thanks in advance!