Influence of measurement geometry on the reflection coefficient of heavy particles

A quantum-mechanical approach has been used to calculate the differential backscattering coefficient for a narrow beam of charged particles incident on a target and recorded by a collimated detector, in the single-scattering approximation and using the continuous stopping model. It is shown that if the radius of the incident beam and the radius of the detector collimator are comparable with the range of the heavy particle in the target, the shape of the energy spectrum of backscattered particles recorded will depend substantially on the geometrical parameters of the incident beam and the detector. The numerical results presented for protons can be used for analysis of experiments on the interaction of a narrow beam with the surface layers of a target