High-precision measurement of electronic stopping powers for heavy ions using high-resolution time-of-flight spectrometry

A new technical and analysis approach based on using time-of-flight (ToF) to determine energy loss has been developed and used to improve the precision of measuring heavy-ion electronic stopping powers from a continuous energy spectrum of particles provided by a typical elastic recoil detection analysis geometry. The particle energies entering and exiting the stopping foil are determined using ToF spectrometry data, with and without the stopping foil. The Si detector is only used to tag identical energies and screen out the extraneous components from the spectrum. This approach, which is applicable to continuous energy measurements, eliminates the well-known calibration problem of Si detectors associated with heavy ions that is shown to lead to a clear deviation in the measured stopping power. Consequently, the stopping powers and the energy dependence are determined with higher precision. In this study, the stopping powers of a number of heavy ions (3 ≥ atomicnumber ≤ 53) in amorphous C, Al and Au have been determined with an absolute uncertainty of less than 2.5%. In some energy regimes, data are provided for the first time. In other energy ranges, the present data exhibit good agreement with most existing data. SRIM stopping power values show a reasonable agreement with experimental data in most cases; however, some deviations from the measured values, up to 15%, are observed around stopping maximum.