Glory and rainbow effects in ion-atom collision

Complete text of publication follows. Post-collision interaction (PCI) is a Coulomb interaction between charged particles originating from an ion-atom collision. It is always present when more then two charged particles leave the collision area. We studied PCI effect calculating the energy shift and the intensity of the Auger line, for the Auger electrons emitted from the Ne target during it's relaxation. For large impact energies (MeV/u energy region), the projectile has small influence on the target relaxation. Even then, PCI can cause line distortion and intensity enhancement that essentially changes the shape, energy and intensity of the Auger line (Kuchiev and Sheinerman [1]). The effect shows resonant-like behavior, and it is the most intensive in the beam direction. Up to now, only the influence of the attractive Coulomb field has been studied, for structureless, positively charged projectiles (mostly protons). Calculating the Ne K-L2,3L2,3 (1D2) Auger line using quantum-mechanical theory of Barrachina and Macek [2] (see also Kuchiev and Sheinerman [3]), the antiproton induced PCI was investigated (repulsive Coulomb field). The antiproton induced PCI is compared with the recently obtained results for the high-energy proton induced PCI [4]. In opposite to the known Coulomb focusing PCI, for antiproton impact the repulsive Coulomb field causes a large line-intensity decrease that appears for projectile velocities smaller than the Auger electron velocity (Coulomb defocusing PCI). Also, the energy shift and the distortion of the Auger line for the antiproton shows a behavior that is opposite to the proton induced PCI [5]. According to the theoretical work of Samengo and Barrachina (and references therein) [6], it is clear that the focusing and defocusing effects can equally occur with any other central potential, provided the scattered particles emerge from a point source. Therefore, the focusing and defocusing PCI can be more general named as glory effect and rainbow effect, known from optics. This was already suggested by Samengo and Barrachina [6]. (author)