The elastic scattering of fast positrons by heavy nuclei

Abstract

The angular distribution of fast positrons scattered elastically by mercury nuclei is investigated in detail using Dirac’s equations in conjimction with numerical tables provided by Bartlett & Watson for the corresponding fast electrons. The ratio of the scattered intensity to that given by the Rutherford formula is obtained as a function of angle for positrons with energies between 25,000 and 1·7 x 10 6 eV. In all cases the ratio is less than unity, decreases with increasing angle of scattering and, in contrast to electrons, does not depend very markedly on the nuclear charge. The maximum asymmetry produced by double scattering of positrons at 90° from mercury nuclei is less than 1 %. It is suggested that experimental investigation of the scattering of fast positrons would be useful in assisting to resolve the present unsatisfactory situation in which there are a number of outstanding divergences between experimental and theoretical results relating to the scattering of fast electrons.