Energy Loss and Energy Straggling of Protons Specularly Reflected from a Graphite Surface

Abstract

Energy loss and energy straggling of fast (v ≈ vFermi) H+ and H0 specularly reflected from a graphite (0001) surface is reported. In the whole range of incidence energies and angles used, the energy loss spectra are dominated by a strong peak with nearly perfect Gaussian distribution. The energy loss and energy straggling data can be correlated comprehensively if they are regarded as functions of the projectile velocity and transverse energy. In good approximation, the energy loss is proportional to Sb(v) · v (Sb(v) is the bulk stopping power) and the energy straggling is proportional to v. The residual-transverse-energy dependence is weak and manifests mainly in an additional small energy loss contribution. Neither the energy loss nor the energy straggling depend on the charge state of the incident projectile.