Abstract
The Utah Fly’s Eye detector has revealed a change in the cosmic ray composition which is correlated with structure in the all-particle energy spectrum. The data can be fitted by a simple model of a steep power law spectrum of heavy nuclei which is overtaken at high energies by a flatter spectrum of protons. The transition occurs near eV. Anisotropy is not detected, so the high-rigidity particles above the transition energy do not originate in the disk of the Galaxy. An outstanding event of 3× eV implies that the highest energy particles originate in the contemporary era of the Universe.
- Received 14 September 1993
DOI:https://doi.org/10.1103/PhysRevLett.71.3401
©1993 American Physical Society