The Physics of Ultra-High Energy Cosmic Rays (UHECR) and Their Detection with Fluorescence Detectors. Charlie Jui ICAHTLT Sedona, AZ, Aug 10,1999. Outline. Introduction to Cosmic Rays Acceleration Mechanisms and Possible Sources Detection of Cosmic Rays
~25% alpha particles
~13% C/N/O nuclei
~10 PeV (Knee)
~5 EeV (Ankle)
Apparent shift from heavy to light composition at the “ankle”*.
Some plausible theories: but it takes some fine tuning to achieve ~10-100 EeV energies.
BUT: any serious model must explain power law and index ~3.
Comparison of integrated exposure at ~ 5 x 1019 eV for different experiments.
(b) seen in rest frame of shock front
(d) rest frame of upstream medium
Discovered Extensive Air Showers