1.
Phys Rev Lett
; 104(16): 161101, 2010 Apr 23.
Article
in English
| MEDLINE
| ID: mdl-20482038
ABSTRACT
We report studies of ultrahigh-energy cosmic-ray composition via analysis of depth of air shower maximum (X(max)), for air shower events collected by the High-Resolution Fly's Eye (HiRes) observatory. The HiRes data are consistent with a constant elongation rate d