Straggling in energy loss of energetic heavy ions (Z ≤ 8) in thick silicon absorber

The energy loss distributions of heavy ions (Z ≤ 8) with high energies (2 MeV/u 50 MeV/u) in thick silicon detectors with uniform thickness have been measured in a wide range of fractional energy loss, ΔE/E₀, where ΔE is the energy loss and E₀ is the initial energy of incident ions. The measured distributions of energetic He, Li, Be, B and C ions are in good agreement with those predicted from Livingston-Bethe's theory when ΔE/E₀ < 0.2. However, the distributions for large fractional energy losses ΔE/E₀ > 0.2. which are much wider than those expected from the theory, are approximately expressed by Stoquert's method considering the effect of velocity decrease into Livingston-Bethe's theory. In the previous experiment of the energy loss of heavy ions from K to Fe in thick Si detectors, Hasebe et al. obtained consistent results for heavier elements. By conbining the results in the previous and this works, it is concluded that the straggling in energy loss of heavy ions from proton to Fe with energies from about 5 MeV/u to a few hundred MeV/u in thick Si-absorber is explained by Stoquert's method.