On the Problem of the Ion Energy Loss in Thin Absorbers

Exact determination of energy loss of ion in materials is still a non-trivial task because of relatively complicated changes of the ion`s stopping power S(E) during transport of the probing ion inside the material structure. Energy loss of ion in the material structure always depends on the current value of continually decreasing energy of the ion, indeed. A purely theoretical approach can be applied to the energy loss calculation in some typical cases. Average energy loss of ion can be determined by means of the Bethe-Bloch analytical theory (1-6) (in high velocity region) and the Lindhard-Scharff-Schiøtt (LSS) theory (7-10) (in low velocity region). Currently, there is no acceptable exact theory to determine the energy loss of ion in intermediate-velocity region (11) and experimental data must be used in that case. Basically, only a finite number of discrete experimental data is always available. Therefore, if the problem how much energy the projectile ion loses in a certain distance travelled is solved, the modelling of function S(E) based on some acceptable assumptions must be applied.In this contribution, we present the energy loss calculations in intermediate-velocity region of ion based on linear interpolation of experimental data. Calculation was carried out for a kapton foil using the data taken from Ziegler, Biersack (12). Energy values of an ion along its trajectory inside the foil were found, and the mean projected range of ion penetrating into the foil was calculated. Finally, the energy resolution was evaluated taking into account straggling provided that the foil is used as an absorber in the ERDA experiment.