## Research Papers in Physics and Astronomy

#### Date of this Version

October 1993

#### Abstract

Distorted wave calculations of the triply differential cross sections for electron-impact ionization of He are presented for electrons sharing ≤ 50 eV excess energy (E_{x}) and having the coplanar, θ_{12} = π geometry. The results are in good agreement with absolute experimental measurements of T. Rösel et al. [*Phys. Rev. A* 46 (1992) 2539-2552] and of A. J. Murray, M. B. Woolf, and F. H. Read [*J. Phys. B* 25 (1992) 3021-3036]. For final state electrons sharing 2 eV excess energy equally, many-body perturbation theory corrections to the authors' first order (e,2e) triply differential cross sections [*Phys. Rev. A* 45 (1992) 4588–4603] are also presented. These results indicate that singlet-triplet interchannel coupling effects in the final state are very significant; that initial state correlations are significant near the perpendicular plane, i.e., θ_{1} = θ_{2} = π/2 ; and that the polarization effects we include are insignificant. Finally, comparison of our first order results with the semiclassical quanta1 theory results of D. S. F. Crothers [*J. Phys. B* 19 (1986) 463–483] shows excellent agreement for excess energies E_{x} ≥ 2 eV and for θ_{1} = θ_{2} = π/2; for E_{x} < 2 eV, the two results diverge as E_{x} → 0, indicating that experimental tests of the Wannier-Peterkop-Rau theory of three-body Coulomb breakup should be carried out in this energy region.

## Comments

Published in

Journal de Physique IV: Colloque C6, supplément au Journal de Physique II, Volume 3, novembre 1993. Published by EDP SCiences. Used by permission.