Search for Possible Geometrical Effect on Stopping Power Measurement

Abstract

The possibility that the geometrical condition might affect the observed energy loss of heavy charged particles in matter has been considered. The energy losses of 8.78 MeV alpha particles in Al, Cu, Ag and Ta have been measured with good and poor geometries. It has been found that the energy losses observed with good geometry are slightly smaller than those observed with poor geometry. It appears that the geometrical effect may really exist, although the amount of the effect is small and comparable with the statistical uncertainties for the present experimental condition. It has been concluded that this effect is not the origin of the discrepancies between our stopping power data for 7.2 MeV protons and the data of Andersen et al. Some discussions have been made on the comparison of stopping powers for 8.2 MeV alpha particles with those for protons of the same velocity.