Analytic calculations of the spectra of ultra high energy cosmic ray
  nuclei. II. The general case of background radiation
  We discuss the problem of ultra high energy nuclei propagation in
extragalactic background radiations. The present paper is the continuation of
the accompanying paper I where we have presented three new analytic methods to
calculate the fluxes and spectra of ultra high energy cosmic ray nuclei, both
primary and secondary, and secondary protons. The computation scheme in this
paper is based on the analytic solution of coupled kinetic equations, which
takes into account the continuous energy losses due to the expansion of the
universe and pair-production, together with photo-disintegration of nuclei.
This method includes in the most natural way the production of secondary nuclei
in the process of photo-disintegration of the primary nuclei during their
propagation through extragalactic background radiations. In paper I, in order
to present the suggested analytical schemes of calculations, we have considered
only the case of the cosmic microwave background radiation, in the present
paper we generalize this computation to all relevant background radiations,
including infra-red and visible/ultra-violet radiations, collectively referred
to as extragalactic background light. The analytic solutions allow transparent
physical interpretation of the obtained spectra. Extragalactic background light
plays an important role at intermediate energies of ultra high energy cosmic
ray nuclei. The most noticeable effect of the extragalactic background light is
the low-energy tail in the spectrum of secondary nuclei.
