ABSOLUTE (E,2E) CROSS-SECTIONS FOR THE ELECTRON-IMPACT IONIZATION OF HELIUM IN ENERGY SHARING KINEMATICS AT 44.6-EV

We present a combined experimental and theoretical study of the electr on-impact ionization of helium at 44.6 eV incident energy. The absolut e coplanar triple differential cross sections (TDCS) are measured in d ifferent geometrical arrangements, with the excess energy being equall y shared between the two outgoing electrons. The measurements are comp ared with the convergent close-coupling (CCC) theory. The measured ang ular distributions of the TDCS are well reproduced by the calculations . Good agreement in magnitude is also obtained after the CCC results h ave been multiplied by a single factor derived from the comparison of the CCC and estimated true single differential cross sections. This su ggests that the CCC theory yields accurate angular and, after rescalin g, absolute distributions for all in- and out-of-plane geometries.