The intensities of cosmic rays at high energies show little deviation from a simple power law dependence on particle energy. Even at the highest energies, where interactions with the microwave background radiation should produce some kind of limit, there are no signs of such a "cutoff". No single mechanism has ever been proposed which can account for this enormous dynamic range of particles. The small deviation from the overall power law at energies around 1000 TeV has been recently studied by several new experiments. The results of these studies and their impact on our overall understanding of cosmic ray origin will be discussed.

ANL Physics Division Colloquium Schedule