Saddle electron emission from ionizing H+ and 3 He2+ collision on Ne

We measured doubly differential ionization cross sections for 100 KeV/u H+ and 3 He 2+ on a Ne target. We studied systematically the effect of a distributed target along the beam trajectory on the electron emission. Low energy electron emission is increased when the gas target is extended. We attribute this effect to the scattering of electrons with distributed target atoms. This result has a direct consequence on the interpretation about how the saddle emission mechanism manifests itself on observed electron distributions. (author)