This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
The Pierre Auger Cosmic Ray Observatory is now measuring every high energy cosmic ray that lands in an area equal to the State of Rhode Island, but located in Argentina (with a sister array of detectors proposed for deployment in Colorado). It has measured more than one million cosmic rays, but 27 of them have proved to be especially meaningful. They are protons or atomic nuclei, whose arrival directions are correlated with the directions to Active Galactic Nuclei within 250 million light years from Earth. Their arrival directions can show us which astrophysical objects are capable of producing these particles that are 10,000,000 times more energetic than the most energetic particles that can be produced on Earth at the Large Hadron Collider (LHC) in Europe. This will lead to an understanding of how Nature endows these special cosmic rays with extraordinary amounts of energy. A primary feature of the Auger Observatory is its blend of two measurement techniques used by previous experiments. First, an array of detectors on the ground samples and detects the cascade of particles, or "air shower," produced in the atmosphere by the interactions of the parent cosmic ray. On dark nights, special telescopes also image the pattern of nitrogen fluorescence, or sky glow, generated by the passage of the particle cascade through the atmosphere. These two detection methods are complementary, so that by combining them we have the best possible measurements of these rarest of particles. We will determine if they are protons or heavy atomic nuclei and whether or not there are also photons (particles of light) or even neutrinos in the mix. The Auger group at Penn State University has experimental and analytical expertise in both detection techniques, and one of us (Sommers) serves as Co-Spokesperson of the International Auger Collaboration. We will continue our varied studies, both experimental and analytical, which address some of the primary questions that must be resolved in minimizing the uncertainties in the combination of the two techniques. In addition, we will exploit the Auger measurements of the air showers produced by these particles to deduce properties of particle interactions at energies far beyond the reach of laboratory studies on Earth.
High-energy cosmic rays are important cosmic messengers that will produce new insights about extreme processes in the universe. Exciting news in cosmology and high-energy astrophysics will be the theme of a continuing series of popular week-long summer workshops that we are offering for high-school teachers, in each of the next 3 consecutive years. The concepts of basic college physics are interwoven into the curriculum, so teachers strengthen their working knowledge of their core curriculum while getting an inside look at what is happening at the forefront of astrophysics research. The participants travel from all over the country to attend these workshops, and teachers from underrepresented groups are particularly encouraged to apply. The teachers are provided with knowledge and tools to bring back into their classroom, to inspire and engage their students, and inform their appreciation of the scientific method. Past participants have consistently expressed an appreciation for the opportunity to get to know personally a number of Penn State scientists at these workshops and beyond, and in particular in being welcomed as partners in our joint mission to educate and nurture the future generations.
