Experimental Particle Astrophysics

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PROPOSAL NUMBER: 0758079INSTITUTION: Northeastern UniversityNSF PROGRAM: PHY - PARTICLE ASTROPHYSICSPRINCIPAL INVESTIGATOR: Swain, John D.TITLE: Experimental Particle Astrophysics ABSTRACTThis is a proposal for a research program in cosmic ray astrophysics focused on the Pierre Auger Observatory (PAO), an instrument designed to investigate the origin and nature of the Ultra High Energy Cosmic Rays (UHECRs), having energies above 10^19 eV. These are of great interest for a number of reasons. First, it is difficult to explain how the highest observed energies are attained in the first place. Second, charged particles at such energies are relatively unaffected by galactic and intergalactic magnetic fields, and thus their arrival directions may reveal their origins. Finally, the interaction of UHECRs with the cosmic microwave background (the "GZK" effect for protons) should rapidly degrade their energies, and thus constrain potential UHECR sources to be relatively nearby objects, within 50 Mpc or so.Because of their low flux, it is impractical to directly detect UHECRs. One can, however, observe the extensive air showers these particles induce when they interact in the upper atmosphere. The PAO employs two distinct detection methods, sensing both the nitrogen fluorescence produced by air showers in the atmosphere and the shower front particles themselves as they arrive at the ground. These two methods have different strengths and limitations, and effectively complement one another. Construction of the southern observatory is nearing completion in the Mendoza Province of Argentina.This group has led the development of the offline analysis software framework and made contributions to physics analysis. They plan to continue their role in software development and to extend their analysis efforts using new data. The broader impact of the program includes the development of technologies and methodologies which cross domains such as connections with computer science and laboratory-based particle physics, and a vigorous outreach program involving regular newspaper, radio, and television appearances in several countries.