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arXiv · 2508.11378

The Mass of Cosmic Rays of Ultra High Energy

A A Watson
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Abstract

A review of several analyses is presented that forces the conclusion that the mass composition of the highest-energy cosmic rays is not proton-dominated. This deduction, combined with the use of a modern hadronic interaction model, should lead to a re-evaluation of the energy spectrum reported by the Telescope Collaboration that may well bring that measurement, and the corresponding one from the Pierre Auger Observatory, into better agreement.

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A A Watson. 2025-08-15. The Mass of Cosmic Rays of Ultra High Energy. https://arxiv.org/abs/2508.11378

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