Argonne National Laboratory is one of the United States Department of Energys largest research centers. It supports more than 200 research projects that range from studies of the atomic nucleus to global climate change research. The laboratory s research projects fall into five categories including basic science, scientific facilities, energy resources, environmental management and national security. Argonne s basic science projects seek solutions to a variety of scientific challenges including experimental and theoretical work in material science, math and computer science. The scientific facilities projects design, build and operate facilities. Argonne s energy resource projects sustain clean, efficient energy sources for the future. The environmental management projects work toward preservation of natural resources and environment, as well as utilizing alternative energy sources and controlling hazardous waste. The company s national security program prepares for counter terrorism in the form of nuclear and biological threats. Argonne National Laboratory holds six national user facilities and numerous branch laboratories throughout the U.S.