The Misleading Nature of the Leaky Box Models in Cosmic Ray Physics
  Many experimental results around and above the energies where the solar modulation affects cosmic ion fluxes were quantified, conceptualized and debated using leaky box models. These models exploit the notion of equilibrium between creation and destruction processes of cosmic ions in an undifferentiated arbitrary volume representing the Galaxy, ignoring the galactic magnetic field, the size of the Galaxy, the position of the solar cavity, the spatial distribution of the sources, the space variation of the interstellar matter and other pertinent observations. Progress in the measurements of the quoted observational parameters rendes obsolete the use of the leaky box models. Specific examples substantiating the inadequacy of the leaky box models are analyzed such as the conversion of the boron-to-carbon flux ratio into grammage and the residence times of cosmic ions in the Galaxy. The unphysical and misleading nature of the leaky box models is ascertained and illustrated at very high energy. 
Antonio Codino and Francois Plouin