Single ionization of helium by antiproton impact

Full text: We study single ionization of the helium (He) atom in collision with antiprotons (p-) in the energy range from 10 to 500 keV. We adopt a semiclassical single center closecoupling (CC) approach in which the electronic wavefunction is expanded in terms of a B-spline basis centered on the nucleus of He atom. We calculate the results in two different approximations: the one active electron (OE) model and the independent particle model (IP). In the IP model we treat the motion of each electron as independent throughout the collision. The transition probability at a fixed impact parameter is calculated in terms of the CC approximation with pseudostates similar to that already used by the authors for p- - H and p- - He+