Capture of antiprotons by some radioactive atoms and ions

Cross sections for antiproton capture are calculated using the fermion molecular dynamics method for ions of current interest in experiments determining nuclear structure of the radioactive nuclei He-8, Li-11, Be-11, and Mg-21. The cross sections for the corresponding neutral atoms are also calculated. It is found that, except for helium, the cross sections for the ion and neutral atom at usual capture energies are similar, i.e., neither the enhanced trajectory curvature nor the absence of the most weakly bound electron have great effect. The behavior of the cross sections is also analyzed at very low collision energies, where the ion cross sections go as 1/E and the neutral cross sections as 1/rootE.