Experimental Particle Astrophysics with the Pierre Auger and HAWC Observatories

This award will enable this particle astrophysics group to continue their analysis of data from the Pierre Auger Observatory, and to participate in the construction of the High Altitude Water Cherenkov (HAWC) Gamma Ray Observatory. Ultra high energy cosmic rays carry information on the structure of matter at its most fundamental level. Yet their origin and mechanisms of interaction with the cosmic microwave background are unknown. The limitations to acquiring such knowledge are related to the rarity of such particles intersecting the Earth's upper atmosphere. The Auger Observatory is currently the world's leading detector of ultra-high energy cosmic rays, and makes these kinds of measurements possible. The analysis of data from the Auger Observatory has already yielded interesting results toward the goal of solving the mystery of the highest energy particles in nature. The group will continue their composition and anisotropy studies at the highest energies where the Auger data are unique and of high value and interest to the scientific community. A search for possible Galactic sources is also part of the proposed work. The HAWC Observatory will be a unique survey instrument for very-high energy gamma ray astronomy, complementing Cherenkov telescopes. It is ideal for mapping extended sources of gamma rays such as diffuse emission from the MilkyWay, and for detecting bursting extragalactic (and galactic) sources. The CSU group will contribute to the construction of HAWC with the fabrication of one of the key components of the detector (the tank bladders). The Broader Impacts will be to continue to reach out to the general public, and to promote undergraduate research and education. The proposed work takes advantage of the resources of the research program to strengthen the quality of undergraduate education, providing a valuable undergraduate experience only available at a research institution.