Analysis of the 2s21S, 2p21D and 2s2p1P autoionizing levels of helium, in proton-helium collisions

The authors have parametrized, using Fano's formula, the three resonances associated with the 2s 2 1S, 2p 2 1 D and 2s2p 1 P autoionizing levels of helium. They were observed in energy spectra of ejected electrons produced by proton-helium collisions. For the 1 S resonance, the authors determined the variations with electron emission angle of the shape parameter q and the resonant continuum cross section sigma r , in the angular range 16.5 degrees to 160 degrees , for 150 keV protons. The dependence on proton energy of these parameters, has also been obtained for 16.5 degrees angle, in the energy range 14 to 150 keV. Additional results concern the variation of the profile parameters for 1 D and 1 P resonances, with ejection angle, at 150 keV.