Electron impact double ionization cross sections of noble gas atoms have been calculated in the binary encounter approximation by using Gryzinski's double binary encounter model. The correct expression for σΔE including exchange and interference as given by Vriens has been used. Hartree–Fock and hydrogenic velocity distribution functions have been used in considering the ejection of the first and the second atomic electron, respectively. Contribution of ionization from inner-shell has also been taken into account. Calculated values of cross sections are found to be in agreement with the experimental observations.
