Additional Collision Cross Sections for Helium Especially in the Ionized Continuum

Abstract

Additional data on the cross sections for the 1 ¹S→2 ¹P transition are reported and compared with extended theoretical calculations. Some additional results on the 1 ¹S→2 ¹S transition are also reported. Collision cross sections and oscillator strengths have been determined for several excitations in the ionized continuum. Oscillator strengths agree well with theory except in the vicinity of the double electron excitations. Two peaks which involve simultaneous excitation of two electrons have been observed. A discontinuity in the ionized continuum on passing through a peak corresponding to a double excitation has been observed.