Conveners
Oct.11AM2
- Gordon Thomson (University of Utah)
We report on an experiment to measure the air-fluorescence from artificial air showers produced at the SLAC National Accelerator Laboratory. The showers have an energy of ~ 10^18 eV and are the result of a superposition of 10^9 10 GeV electons in a picosecond wide pulse. This electron pulse is pre-showered in 1, 2 or 3 radiation lengths of alumina ( Al2O3) and then allowed to develop in...
Current data on the cosmic ray spectrum and composition from the knee to the GZK range provide important information and reveal interesting features, which shed new light about the transition from Galactic to extragalactic cosmic rays. A general description and understanding of this transition it shown to be possible within a simple framework involving only two components, a Galactic one with...
Among other questions, there are two long-standing mysteries about cosmic rays at the highest energies: are they mostly composed by protons or nuclei? Are their sources steady or transient? In this work, we aim to exam one out of the four scenarios led by these questions, namely, the possibility that the highest-energy particles are protons from steady sources. We start out by discussing the...
It will be argued that the detection of anisotropies at ultra-high energies brings important constraints on the composition of ultra-high energy cosmic rays. In particular, the pattern of anisotropies seen by the Telescope Array experiment suggests that protons are present at these energies. This, in turn, puts strong constraints on the sources.
These constraints as well as the physics of...
