ANISTROPIC PENETRATION OF POSITRONS IN MONOCRYSTALLINE RBBR

An investigation was made of the dependence of K‐line‐X‐ray yield by positrons with an energy spectrum from 120 to 480 keV (average energy 220 keV) on the angle between the positron beam (divergence ± 0.6°) and 〈100〉 of a RbBr single crystal. There is a nearly 90% reduction of the yield with a HWHM of nearly 2° in the case of bombarding parallel to 〈100〉. In particular, a comparison is given between this positron effect and the behaviour of X‐ray excitation by channelled protons. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim