Study of stopping of natural Cu ions in Au at low velocities

Author(s)

Roberto Linares

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2005-11-09

Examining board members

Roberto Vicencotto Ribas; Manfredo Harri Tabacniks; Jun Takahashi

• Advisor: Roberto Vicencotto Ribas

Abstract

The energy loss of ions in materials is an important issue not only because of its direct applications in analytic techniques of materials but also for studying the basics of ion-atom interactions. Nevertheless, the Stopping Power of heavy ions in solids is still poorly understood which is especially true at low velocities mainly due to the complicated dependence on the atomic numbers of the stopper medium and of the stopping ion. In this work we present new experimental data for Copper ions slowing down in Gold foil in the velocity range of 2 to 4% of the velocity of light. Experimental data were obtained using the elastic scattering technique, where primary beams of 16O and 28Si, with energies from 35 to 52 MeV and 49 to 79 MeV respectively, were used to scatter Cu íons from a thin target ( 160 g/cm2). The scattered primary beam is detected at 60 with a Si detector, producing recoiling atoms of the target in an angle given by the elastic scattering kinematics. The recoiling ions in temporal coincidence with the scattered primary beam will compose the secondary beam. The energy loss, in a gold foil with thickness about 530 g/cm2, was obtained by measuring the energy of the secondary beam with a Si detector, with and without the Au foil intercepting the recoiling ions. Experimental results were compared with theories and semi-empirical models applied to this case. Good agreement between Unitary Convolution Approximation (UCA) prediction and our data is observed. (AU)