  TeV gamma-rays may provide significant information about high energy
astrophysical accelerators. Such gamma-rays can result from the
photo-de-excitation of PeV nuclei after their parents have undergone
photo-disintegration in an environment of ultraviolet photons. This process is
proposed as a candidate explanation of the recently discovered HEGRA source at
the edge of the Cygnus OB2 association. The Lyman-alpha background is provided
by the rich O and B stellar environment. It is found that (1) the HEGRA flux
can be obtained if there is efficient acceleration at the source of lower
energy nuclei; (2) the requirement that the Lorentz-boosted ultraviolet photons
can excite the Giant Dipole resonance implies a strong suppression of the
gamma-ray spectrum compared to an E_\gamma^{-2} behavior at energies \alt 1 TeV
(some of these energies will be probed by the upcoming GLAST mission); (3) a
TeV neutrino counterpart from neutron decay following helium
photo-disintegration will be observed at IceCube only if a major proportion of
the kinetic energy budget of the Cygnus OB2 association is expended in
accelerating nuclei.
