Pierre Sokolsky New submissions for Tue, 12 Jun 07

While it appears that the GZK puzzle has now been set to rest, the underlying questions are as urgent and burning as ever: what are the sources of UHE cosmic rays, what is the nature of the acceleration mechanism and what is the composition of the particles? Tantalizing hints of point sources have begun to appear in the last decade. Significant measurements of anisotropy, both on large and small scales, seem just within reach. The new generation of detectors, with order of magnitude larger sensitivities and excellent angular resolution should make a great impact in this area.