Results from symmetric and non-symmetric energy sharing (e, 2e) experiments in the perpendicular plane

Results are presented of (e, 2e) coincidence measurements on helium in the perpendicular plane, defined as the plane orthogonal to the incident electron trajectory. The incident energy is varied in the range from 10 to 80 eV above the ionization threshold and results are presented for both symmetric energy sharing, where the outgoing electrons have the same energy, and for non-symmetric sharing. The experimental apparatus used to collect these results is a fully computer controlled and computer optimized spectrometer able to access a wide range of geometries from the perpendicular to the coplanar geometry.