CONICET | Buscador de Institutos y Recursos Humanos

We present a theoretical and experimental study of the subshell resolved L-shell ionization of relativistic targetssuch as 73Ta, 78Pt,90Th, and 92U. The measurements of x-ray production cross sections by (84?140 MeV) Si+qions (q = 8; 12), were held at the Inter-University Accelerator Centre of New Delhi. Multiple-hole fluorescenceand Coster-Kronig yields were used to obtain the Li(i = 1?3)ionization cross sections from the measured x-rayproduction cross sections of Lℓ, Lα, and Lβ, Lη, and Lγ lines. The experimental results are compared with ab initiotheoretical calculations by means of the shell-wise local plasma approximation (SLPA). This model uses thequantum dielectric formalism to obtain the total ionization cross sections from an initial ground state. The wavefunctions and binding energies of the different targets were obtained by solving the fully-relativistic Diracequation using the HULLAC code package. These calculations are based on first-order perturbation theory with acentral field, including Breit interaction and quantum electrodynamics corrections. The present SLPA ionizationcross sections of the L-shell are found to be independent of the charge state of the Si ions. The experimentalobservations display also quite similar character if the correct mean projectile charge state inside the target isused for including the multiple ionization effect during ion-solid collisions. A general good agreement betweenthe experimental measurements and full theoretical calculations supports the reliability of present results. Thecomparison also includes the well-known ECPSSR and ECUSAR semi empirical approximations. We noted thatthe ECUSAR results agree well with the SLPA, while the ECPSSR cross sections are rather low.