Cross Section for a K -Shell Vacancy Produced by Heavy Projectile in an Independent-Particle-Model Atom

In the Born approximation as the interaction occurs with only one electron, the total cross section for producing a K-shell vacancy with a heavy projectile is obtained by requiring the electron to be excited above the Fermi sea. We demonstrate that for an independent-particle model of the atom this result is true to all orders of the Born series. This means the codes currently developed for proton-hydrogen scattering are immediately applicable to K-shell ionization.