Proposal to Operate and Analyze Data from the High Resolution Fly's Eye Detector (Part IV)

University Of Utah, Salt Lake City UT

Investigators

Abstract

This is a proposal requesting funds to continue to operate the High Resolution Fly's Eye (HiRes) Observatory located on the U.S. Army's Dugway Proving Ground, Utah. The detector is comprised of two stations, separated by 12.6 km, which detect ultra high-energy cosmic rays via nitrogen fluorescence in the atmosphere. The goals of the experiment are to study the spectrum, composition, and anisotropy of cosmic rays starting from 1018 eV to beyond 1020 eV. Previous experiments have shown evidence that the spectrum continues past the predicted Greisen-Zatsepin-Kuzmin (GZK) cutoff. The nature of the events above the cutoff is a puzzle and has stimulated much theoretical speculation. Monocular HiRes data strongly confirm the dip structure observed by the stereo Fly's Eye at 3x1018 eV and the hardening of the spectrum around the GZK cut-off energy. A few outstanding events are observed above 1020 eV. Both the location of the dip structure and the flux of events above 1020 eV are in significant disagreement with published results from the AGASA ground array. This proposal describes how the additional operation of this detector will resolve these and other outstanding issues. HiRes has developed a vigorous educational outreach program, called ASPIRE. This project, conducted in collaboration with the Utah State Office of Education, communicates the excitement of the HiRes scientific research to the general public. The collaboration proposes to continue this successful outreach effort.