Double-Electron Capture by Positrons Passing Through Helium

The total cross section for double-electron capture by positrons passing through helium atoms is calculated by the Born approximation for positron energies up to 250 eV. It is found that the maximum value of the cross section is 0.0058 $\pi {a_0}^2$ and occurs at the positron energy of 100 eV. This value turns out to be of about 2 orders of magnitude smaller than the existing values of the cross section for single-electron capture by positrons in helium.