INT-96 Szalewicz This U.S.-Bulgaria Cooperative Research award will study "Metastable States of Exotic Helium Atoms and Delayed Annihilation of Antiprotons in Helium." The principal researchers are Dr. Krzysztof Szalewicz of the University of Delaware and Dr. Dimitre D. Bakalov of the Institute for Nuclear Research and Nuclear Energy of the Bulgarian Academy of Sciences. The purpose of the project is to provide a high accuracy of ab initio quantum mechanical description of the metastable states of antiprotonic helium and of the phenomenon of delayed annihilation of antiprotons in helium. The project will give precise theoretical values for the energy levels of the few-body bound systems that are formed when stopping negative muons or antiprotons in helium, as well as the rates of various transitions (Auger, radiative, and laser stimulated) between these levels. The Coulomb energy levels of the muonic and antiprotonic helium-like atom will be calculated with a relative accuracy of 10 to the -7 using variational methods. The relativistic and quantum electrodynamics corrections -- including the fine and hyperfine splitting -- will be evaluated in the first order of perturbation theory. The Zeeman splitting of the levels in external homogeneous magnetic field of intensity up to 10 to the 4th Gauss will also be evaluated. Finally, the effect of molecular clusters will be estimated. This work should answer very important current questions about antimatter which could not be accomplished without this collaboration. This research in physics and astronomy fulfills the program objectives of bringing together leading experts in the U.S. and Bulgaria to combine complementary efforts and capabilities in areas of strong mutual interest and competence on the basis of equality, reciprocity, and mutuality of benefit. *** ??
