This Americas Program award will support Professor James J. Kolata of the University of Notre Dame, Indiana, in a research collaboration with Professors Eli Aguilar and Enrique Martinez of the Mexican Nuclear Research Center (ININ). The proposed research will study details of fusion mechanisms in the reaction of atomic nuclei. The goal of the research is to achieve a basic understanding of heavy-ion fusion, a process in which the constituent protons and neutrons of two reacting atomic nuclei drastically re-arrange to form a compound nucleus. Sub-barrier fusion is now known to be stronger than what was expected on the basis of simple theoretical models of these processes. Several explanations have been put forward to explain this discrepancy but further study is needed to understand this phenomenon. The proposed collaboration is an extension of previous mutually beneficial projects involving staff members of the Mexican Research Center. The data analysis phase of the work will be carried out primarily in Mexico while the Notre Dame group will bring to the collaboration its expertise in heavy-ion physics and sub-barrier fusion.