Stopping power measurements for 4-5MeV/nucleon 16O, 40Ar, 63Cu and 84Kr in C, Al, Ni, Ag and Au

The stopping powers for (4 and 5 MeV/nucleon) 16O, 40Ar, 63Cu and 84Kr have been measured in C, Al, Ni, Ag and Au media. The experimental technique consists in measuring accurately the energy of protons elastically scattered at zero degree by the incident and degraded beams. The experimental results have been compared with stopping powers calculated in different ways. Discrepancies as large as 30% have been observed for the heaviest ions in light media (C, Al), the experimental values being higher than the calculated ones. Moreover, this comparison indicates that, from these calculations, no agreement can be obtained in the whole range of incident ions and stopping media. On the contrary, a quantitative agreement was obtained by a new calculation mode which takes into account the variation of the moving ion effective charge with the atomic number of the stopping medium