PNNL

Abstract

The stopping powers in silicon carbide (SiC) of nine different ions, ranging from Be to Au, have been determined using a time-of-flight elastic recoil detection analysis (TOF ERDA) set-up. In transmission geometry, the energy loss of ions in a self-supporting SiC film is measured over a continuous range of recoil energies, from tens to hundreds keV/nucleon, using Time-of-Flight (TOF) spectrometry. By essentially calibrating the Si detector for each channel using the TOF spectrometer, the error resulting from nominal energy calibration is eliminated. An uncertainty of less than 4% is achieved in the stopping measurements. Stopping powers predicted by SRIM (The Stopping and Range of Ions in Matter) code are in reasonable agreement with much of the experimental data, and the SRIM 2003 predictions are in somewhat better agreement than SRIM 2000 for most ions. There are, however, still some discrepancies between SRIM predictions and the experimental data. For Ni, I and Au ions, the predicted values from SRIM 2003 are up to 40% less than the measured values. The stopping data from this study as well as previous work suggest that both the modified Bohr and Bloch formulas are suitable for scaling the stopping number of heavy ions in SiC within the classical interaction regime, and the Bloch formula is more appropriate to use at higher energies.