BACKSCATTERING STUDIES OF LI-7, C-12 AND O-16 IONS AT ENERGIES 3-15 MEV

We report the experimental results on the backscattering analysis of 3 .0-9.0 MeV Li-7, C-12 ions and 3.0-15 MeV O-16 ions. Energy resolution and mass resolution for these ions were measured on a double layered Au/Cu thin film (50 Angstrom thick) from backscattering spectra using a passivated implanted planar Si (PIPS) detector (Canberra PD 50-11-30 0). The backscattering data from top Au film (25 Angstrom thick) and n atural Cu layer were used to determine the detector energy resolution and mass resolution, respectively. Our measured spectra show the advan tage of using PIPS detector for Li-7 ion resulting to a good energy re solution. The measured value is 21 keV for 5 MeV Li-7 ions as compared to 36 keV obtained previously using a partially depleted Si detector. As for mass resolution far Li-7, C-12 and O-16 ions our measured spec tra show a clear separation of Cu-63 and Cu-65 peaks. To examine the a ccuracy of the stopping power for these heavier ions in different elem ents predicted by TRIM-95, we measured the backscattering spectra on t hin films of Al, Cu and Ag, and determined the corresponding thickness from a RUMP analysis and compared the backscattering data for the He- 4 ions.