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The differential and total cross sections for electron capture by positronsfrom helium atoms are calculated using a first-order distorted wave theorysatisfying the Coulomb boundary conditions. In this formalism a parametricpotential is used to describe the electron screening in a consistent andrealistic manner. The present procedure is self consistent because (i) itsatisfies the correct boundary conditions and post-prior symmetry, and (ii) thepotential and the electron binding energies appearing in the transitionamplitude are consistent with the wave functions describing the collisionsystem. The results are compared with the other theories and with the availableexperimental measurements. At the considered range of collision energies, theresults agree reasonably well with recent experiments and theories.  [Note: This paper will be published on volume 42 of the Brazilian Journal ofPhysics]

A Self-Consistent Model for Positronium Formation from Helium Atoms