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 50-11-300). The backscattering data from top Au film (25 Angstrom thick) and natural Cu layer were used to determine the detector energy resolution and mass resolution, respectively. Our measured spectra show the advantage of using PIPS detector for Li-7 ion resulting to a good energy resolution. 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 spectra show a clear separation of Cu-63 and Cu-65 peaks. To examine the accuracy of the stopping power for these heavier ions in different elements predicted by TRIM-95, we measured the backscattering spectra on thin 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.