Angular dependence of autoionisation linewidths due to post-collision interaction in e-He collisions

In this paper we present measurements of energy positions and widths of ejected- and scattered-electron profiles in electron-helium collisions. The energy of the incoming electrons is chosen such that following the excitation and the subsequent autoionisation of a doubly excited helium atom the ejected and the scattered electrons have roughly the same energy. An angle-dependent broadening of the ejected-electron profiles is observed; this may be caused by post-collision interaction (PCI) between the two electrons. The experimental results are in qualitative agreement with a semiclassical description of PCI in this energy region. (author)