Energy spectra and angular distributions of charged particles backscattered from solid targets

In this study, the EGSnrc ( Electron Gamma Shower) Monte Carlo radiation transport code is used to simulate the energy spectra and the angular distributions of charged particles backscattered from solid targets. The study covers the energy range 10-70 keV, which is of interest to applied physics fields such as scanning electron microscopy, microprobe analysis and x-ray imaging. Simulation results are compared with experimental data from 11 different published experiments (1954-2002). Comparisons include electrons and positrons, low-and high-Z targets, normal and oblique incidence, different backscatter angles and backscatter planes, and backscatter from thin films. EGSnrc simulation results show excellent agreement with the majority of the published experimental data. Possible experimental and computational uncertainties explaining the few noted discrepancies are discussed. This study concludes that EGSnrc produces accurate backscatter data in the kilovoltage energy range. A documented EGSnrc user-code customized for backscatter calculations is available from the authors at http://www.physics.carleton.ca/clrp/backscatter.