Positron impact ionisation of He ion.

Triple differential cross-sections (TDCS) of a hydrogenic (He⁺) ion has been studied by positron impact using coplaner geometry for both symmetric and asymmetric kinematics in the intermediate and medium high incident energy region. TDCS has also been studied of He⁺ ion by electron impact for symmetric kinematics taking account of the electron exchange effect. The final state wavefunction is chosen as the correlated 3-body Coulomb wavefunction satisfying the exact asymptotic boundary condition. The long range Coulomb interaction in the initial channel between the ionic target and the projectile has also been taken into account properly. For positron impact, the collision is found to be almost recoilless at lower incident energies, in contrast to the strong recoil peak noted in the case of electron impact ionisation. For electron impact, the exchange effect is found to be significantly high for equal energy sharing in the final channel. [ABSTRACT FROM AUTHOR]