Latest Results from HiRes

Abstract

HiRes has made the first statistically significant observation of the Griessen-Zatsepin-Kuzmin suppression, by fitting the ultra high energy cosmic ray spectrum observed in monocular mode by the two HiRes detectors to a broken power law model. We find the break to be at an energy of $5.6\times 10^{19}$ eV, with a significance of $5.3\sigma$;. The significance is determined by Poisson statistics where we expect 43.2 events above the break point, but observe only 13. We have also looked for correlations between HiRes stereo events and active galactic nuclei. We observe no statistically significant correlation in a number of different tests. We have performed a search for upward going showers, which would be indicative of neutrinos propagating through the Earth and interacting just below the surface. Observing no such events, we set a limit on the electron neutrino flux. This limit is significantly lower in this topology than limits on the other types of neutrinos due to the LPM effect greatly increasing the available target mass for neutrino interactions. Finally we look forward to improving these and other results in our work in the Telescope Array.

10 pages, 8 figures, to appear in the Proceedings of the 20th Recontres de Blois, Blois, France, May 2008

References in corpus (6)

• Correlation of the highest energy cosmic rays with nearby extragalactic objects
• Upper limit on the diffuse flux of UHE tau neutrinos from the Pierre Auger Observatory
• Search for Correlations between HiRes Stereo Events and Active Galactic Nuclei
• Cosmic Rays: The Second Knee and Beyond
• An upper limit on the electron-neutrino flux from the HiRes detector
• Observation of the GZK Cutoff Using the HiRes Detector

Cited by in corpus (6)

• Towards a Noncommutative Astrophysics
• AUGER-HiRes results and models of Lorentz symmetry violation
• Superbradyons and some possible dark matter signatures
• Preon models, relativity, quantum mechanics and cosmology (I)
• Lorentz violation, vacuum, cosmic rays, superbradyons and Pamir data
• Implications of cosmic ray results for UHE neutrinos