This award will provide continued funding for the scientific analysis of data taken with the IceCube neutrino detector. Extensive efforts by the University of Wisconsin - Madison group towards improving the calibrations and the analysis software for the final detector configuration, including implementing significant refinements of the understanding of the optical properties of the ice, have resulted in an improved instrument. IceCube has detected more than 300,000 atmospheric neutrinos during construction, some with energies that exceed by more than three orders of magnitude the energies of those produced with accelerator beams. The construction of DeepCore, an infill of the IceCube array over a significant instrumented volume of very clear ice in the bottom half of the detector, has lowered the threshold to 10 Gigaelectronvolts (GeV). This immediately resulted in the observation of atmospheric neutrino oscillations at energies previously inaccessible with statistical significance greater than five standard deviations. On the other end of the energy spectrum, with IceCube's improved effective area, measurements have reached sensitivity to the flux of neutrinos produced in the interactions of extragalactic cosmic rays with cosmic microwave photons, thus creating a new opportunity to reveal their sources. IceCube's sensitivity has reached a level where, from general arguments, they must observe supernova remnants and gamma-ray bursts if these are indeed the sources of the galactic and extragalactic cosmic rays, respectively.
Broader Impacts: IceCube results will enhance scientific and technological understanding on many levels through broad dissemination of the results and experiences. IceCube is in a unique class of projects that inspire the innovative capacity of a new generation of American scientists and engineers. The group's approach has been to make IceCube science and resources available to existing education and outreach programs with a proven record of success.
