  The identification of very high energy photons is of great importance for the
understanding of the origin of extreme energy cosmic rays (EECR). Several can
be the sources of high energy photons at Earth. A guaranteed component is the
flux of high energy photons expected as a consequence of the interaction of
cosmic rays with the cosmic photon background. Another contribution may be
expected as by-product at the acceleration sites of protons and nuclei,
although such flux should be strongly suppressed for distant sources. On the
other hand, top-down scenarios involving the decay of super heavy relic
particles or topological defects, even if not currently favored, have as a
characteristic signature an increasingly dominant flux of photons at the
highest energies. In this work we study the statistical separation between
hadron and photon showers at energies where both, LPM effect and magnetospheric
interactions are important for the development of the cascades. We consider a
detector with the same orbital characteristics as JEM-EUSO, but disregard
trigger and reconstruction efficiencies, in order to define the maximum ideal
discrimination power attainable.
