Emission-Angle Dependence of Electron Transmission through Thick Layers with Initial Energy of 24.8 MeV

Abstract

Electrons of 24.8-MeV energy were incident on thick layers of C, Al, Cu, and Pb. Energy spectra f ( E , θ) of transmitted electrons were measured at angles θ of 0°, 5°, 15°, 30°, and 60°. The material thicknesses ranged from ∼1 to ∼3.6 g/cm 2 , or ∼10 to ∼30% of the continuous slowing-down approximation range of the incident electrons in each material. The total number of emerging electrons s (θ), defined as \(\int f(E, \theta)\text{d}E\), was evaluated for each material. The angular dependence of s (θ)/ s (0°) is compared with the Moliěre theory of electron multiple scattering including an energy-loss correction, a large-angle correction, and a modification of screening angle. The experimentally obtained s (θ)/ s (0°) relative to the calculated one increases as θ increases, and this is more remarkable for materials of low Z than in the case of high- Z materials.