Current status of antiproton impact ionization of atoms and molecules: theoretical and experimental perspectives

Experimental and theoretical progress in the field of antiproton-impact-induced ionization of atoms and molecules is reviewed. We describe the techniques used to measure ionization cross sections and give an overview of the experimental results supplemented by tables of all existing data. An attempt is made to discuss the multitude of theoretical approaches and models of the last 10-15 years in terms of a few categories which characterize their level of sophistication. This sets the stage for in-depth comparisons of experimental and theoretical results and a critical evaluation of the present status of our understanding of antiproton impact ionization. The related issues of energy loss measurements and antiproton therapy are briefly described and directions for possible future work are pointed out as well. (topical review)