Summary Where we are. Physics questions to be answered. Why Auger is a good investment for Fermilab and the US. Fermilab Auger Group proposal.

The Auger Observatory Where are we? World’s largest Cosmic Ray Observatory Successful international collaboration Important science at the Cosmic Frontier Major impact on the Science of UHECRs Fermilab and the US play leadership role Observatory operation highly efficient Detector characterization and data quality continually improving Exposure will double in four years.

The Auger Observatory Questions: What are Xmax and anisotropy telling us about composition and particle interactions at extreme energies? Will further investigation of the unexplained muon excess help sort out the Xmax conundrum? Is the suppression of the spectrum indeed the GZK feature or decreasing power in the sources? What will the details of the spectrum and composition around the ankle tell us about transition to extragalactic sources? This list is not exhaustive - the collaboration is working hard on a long range plan

The Auger Observatory Why Auger is a good investment for Fermilab and the US Impact on both astrophysics and particle physics Operating cost very modest (<3.5% of construction cost) Highly leveraged, risk-free, investment in science for the US (<20% of operating cost) An opportunity to retain US leadership in an important science field at the Cosmic and Energy Frontiers

The Auger Observatory What Auger Fermilab group proposes: For the next four years: Meet our commitments to the Collaboration Continued participation in the physics analysis Continued detector studies Continued leadership roles in the Observatory Adequate support to carry out these activities In three years a review to assess progress and evaluate case for participation beyond 2015.