Energy loss of fast clusters through matter

Abstract

Energy loss in the MeV range of simple clusters impinging on thin carbon targets has been measured using a time-of-flight method. Stopping-power ratios defined as the ratio of the stopping power of the cluster to the sum of the stopping powers of the constituent atoms moving at the same velocity were investigated. Stopping- power ratios close to unity were observed for ${\mathrm{O}}_{2}$ and ${\mathrm{B}}_{3}$ clusters, while deenhancement effect is observed in the stopping-power ratios of ${\mathrm{C}}_{3}$ and ${\mathrm{C}}_{4}.$ The experimental results are compared both with an existing theoretical model, which takes into account the spatial correlation of the fragments, and with a simple united-atom model, which also includes the charge state evolution of the fragment ions inside the target.