The shell-wise local plasma approximation, applications to stopping power, straggling and ionization of iner-shells

C. C. MONTANARI

Paris

Workshop; Brandt Ritchie Workshop; 2006

The local plasma approximation (LPA) [1] is a known model to deal with ion solid interactions within the dielectric formalism [2]. It describes the response of target bound electrons as that of a free electron gas of local density. In the present contribution we employ a shell-wise version of the local plasma approximation (SLPA), by considering not only local but also independent shell response [3,4]. We present results of the SLPA for stopping power and energy straggling of neutral ions (H, He and Li) in solids. The different charge states of the ion inside the solid are taken into account, together with the contribution from inelastic transitions of the projectile electrons (excitation or electron loss). The accord with the experimental data available in the range of intermediate and high energies (keV/u-MeV/u) is quite good. In the case of energy loss straggling, the comparison with the experimental data of the latest twenty years and the influence of rougosity and inhomogenity of the foils are discussed [5]. The shell-wise description lets us to have an insight on the contribution and energy threshold of each shell of target electrons. On the other hand, the same model is employed in typical atomic calculations such as ionization cross sections. K-shell ionization of Cu and Fe by different ions is calculated with the SLPA and compared with the experimental data [6].