Absolute 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 electron-impact ionization of helium at 44.6 eV incident energy. The absolute coplanar triple differential cross sections (TDCS) are measured in different geometrical arrangements, with the excess energy being equally shared between the two outgoing electrons. The measurements are compared with the convergent close-coupling (CCC) theory. The measured angular distributions of the TDCS are well reproduced by the calculations. Good agreement in magnitude is also obtained after the CCC results have been multiplied by a single factor derived from the comparison of the CCC and estimated true single differential cross sections. This suggests that the CCC theory yields accurate angular and, after rescaling, absolute distributions for all in- and out-of-plane geometries.