COLLISIONS OF FAST ELECTRONS WITH POSITRONIUM ATOMS

Elastic and inelastic collisions of fast non-relativistic electrons with positronium atoms have been studied in the Born-Ochkur approximation. It has been shown that exchange plays an important role for transitions between states with the same parity as in this case the direct scattering amplitude vanishes. Numerical results for the total and ortho-para conversion cross-sections for the 1s --> 1s, 1s --> 2s and 1s --> 2p transitions have been presented for projectile energies varying from 0.1 to 10 keV. According to charge symmetry, presented results apply also to positron projectiles.