Abstract
We describe the measurement of the depth of maximum, , of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of below , and above this energy. The measured shower-to-shower fluctuations decrease from about 55 to . The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.
- Received 7 December 2009
DOI:https://doi.org/10.1103/PhysRevLett.104.091101
©2010 American Physical Society
Synopsis
Air showers from ultrahigh-energy cosmic rays
Published 1 March 2010
Cascades created by cosmic rays interacting with the atmosphere provide clues about the mass composition of ultrahigh-energy cosmic rays.
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