  High energy cosmic rays reach the surface of the Sun and start showers with
thousands of secondary particles. Most of them will be absorbed by the Sun, but
a fraction of the neutral ones will escape and reach the Earth. Here we
incorporate a new ingredient that is essential to understand the flux of these
solar particles: the cosmic ray shadow of the Sun. We use Liouville's theorem
to argue that the only effect of the solar magnetic field on the isotropic
cosmic ray flux is to interrupt some of the trajectories that were aiming to
the Earth and create a shadow. This shadow reveals the average solar depth
crossed by cosmic rays of a given rigidity. The absorbed cosmic ray flux is
then processed in the thin Solar surface and, assuming that the emission of
neutral particles by low-energy charged particles is isotropic, we obtain (i) a
flux of gammas that is consistent with Fermi-LAT observations, (ii) a flux of
100-300 neutrons/(year m^2) produced basically in the spallation of primary He
nuclei, and (iii) a neutrino flux that is above the atmospheric neutrino
background at energies above 0.1-0.6 TeV (depending on the solar phase and the
zenith inclination). More precise measurements of the cosmic ray shadow and of
the solar gamma flux, together with the possible discovery of the neutron and
neutrino signals, would provide valuable information about the magnetic field,
the cycle, and the interior of the Sun.
