  We consider a generalized statistical mechanics model for the creation
process of cosmic rays which takes into account local temperature fluctuations.
This model yields Tsallis statistics for the cosmic ray spectrum. It predicts
an entropic index q given by q=11/9 at largest energies (equivalent to a
spectral index of alpha=5/2), and an effective temperature given by (5/9)T_H,
where kT_H approximately equal to 180 MeV is the Hagedorn temperature measured
in collider experiments. Our theoretically obtained formula is in very good
agreement with the experimentally measured energy spectrum of primary cosmic
rays.
