Characteristic X-Ray Production in Single Crystals (Al, Cu) by Proton Bombardment. I. Protons of 70 to 100 keV

Abstract

Characteristic x rays have been observed from single crystals of aluminum ($K$ shell) and copper ($L$ shell) during bombardment by 70- to 100-keV protons. The thick-target yield was found to be sensitive to the orientation of the crystals. Studies have been performed in the region of the [011] direction (at 45° to the crystal surface normal) and across the (100) plane at 30° to the normal. A yield contour at the [011] direction is presented over an angular region of 20°×20° and is compared with a polycrystalline value. A single-crystal yield exceeded the polycrystalline value by as much as 30% at one point. For copper the largest observed maximum-to-minimum yield ratio in the vicinity of the [011] direction was 15 to 1. The effect of surface contamination has been measured for selected sweeps. Also included is a calculation of a protoncrystal potential and comparison with a planar-averaged Nielsen potential.