Electron capture across a nuclear resonance in the strong potential Born approximation

Abstract. The strong potential Born theory for charge transfer in fast, asymmetric ion-atom collisions has been extended to allow for nuclear resonant scattering using distorted nuclear waves. In the absence of a nuclear resonance, the semiclassical result is recovered. A large variation in the capture probability is found when the projectile energy passes through the resonance. As examples, we present results for the capture from the target K shell in the collisions of protons with 22Ne and 28Si, as well as for capture from the K and L shells of 58Ni in collisions with protons, and of I6O, "Ne and 28Si by He2+ impact. 1

Charge transfer at large scattering angles in the strong potential Born approximation

Abstract. We have calculated the Is-Is charge transfer probability for large projectile scattering angles in asymmetric ion-atom collisions, using the strong-potential Born approximation and including the effect of recoil on the projectile states non-perturbatively. A significant angular dependence is found. Numerical results for Is-Is capture in 0.3-20 MeV proton impact on C and Ne are presented, showing good agreement with recent experimental results. 1

On the applicability of the impulse approximation for radiative capture into bound and continuum states

Abstract. A comparison between the impulse approximation ( IA) and the strong-potential Born approximation (SPB) is carried out for radiative capture of a target electron into excited bound states ( R E C) and into continuum states (radiative ionisation, R I) of the projectile. It is found that in the vicinity of the peak in the photon spectrum, the deviations of the SPB from the IA are small but do not disappear either for excited states or for continuum states with low momentum K,. The contribution of RI to the forward peak is calculated for the systems C6++ He and Ne”++He, showing a strong skewness towards the high-energy side. For electrons with high K,, large deviations between SPB and IA indicate the breakdown of an atomic description. 1