Electronic stopping cross sections for 30–300 keV protons in materials with 23 ⩽ Z2 ⩽ 30

Abstract

The simplified stopping function has been successfully applied by Ziegler [3] to evaluate electronic stopping cross sections for helium ions in all materials. In a preceding work [4] we found that helium stopping cross sections extrapolated from hydrogen data by means of the simplified stopping function are of poor accuracy, if the corresponding proton stopping cross section is near its maximum as a function of ion velocity. This effect might be attributed to the fact that those maxima occur at different velocities for different ions. Therefore the goal of our experiments was to exactly measure the proton velocity at maximum stopping cross section in different materials. Using a magnetic spectrometer the energy losses for protons near the maximum stopping cross section ( E ≈ 100 keV) were measured in thin foils of C, Al, Si, V, Cr, Fe, Co, Ni, Cu, Zn, Ge, Ag and Au. The energy at maximum stopping could be located within a few keV. The position of the maximum only varied slightly for the elements with 23 ⩽ Z 2 ⩽ 30, whereas for C and Au the energy at the maximum was shifted noticeably. Tables are given for the stopping cross sections.