Electron-photon angular correlations in electron-helium collisions for 3¹P excitations

Abstract

Electron-photon angular correlations have been measured by detecting, in delayed coincidence, electrons inelastically scattered from helium and photons emitted in decays from the 31P level. The measurements have been carried out using both the 31P-11S (53.7 nm) line and the 31P-21S (501/6 nm) line. Analysis of the data yields the ratio of differential cross sections for exciting 31P magnetic sublevels lambda and the absolute value of the relative phase mod chi mod between the corresponding excitation amplitudes for electron scattering angles between 10 degrees and 30 degrees at incident electron energies in the range 50 eV to 150 eV. Data on the atomic orientation is also presented. The results are compared with the predictions of the first Born approximation and a recent multichannel eikonal calculation.