  Electromagnetic energy losses of charged pions and muons suppress the
expected high energy, >1E18 eV, neutrino emission from sources of ultrahigh
energy, >1E19 eV, cosmic-rays. We show here that >1E19 eV photons produced in
such sources by neutral pion decay may escape the sources, thanks to the
Klein-Nishina suppression of the pair production cross section, and produce
muon pairs in interactions with the cosmic microwave background. The flux of
muon decay neutrinos, which are expected to be associated in time and direction
with the electromagnetic emission from the sources, may reach a few percent of
the Waxman-Bahcall bound. Their detection may allow one to directly identify
the sources of >1E19 eV cosmic-rays, and will provide the most stringent
constraints on quantum-gravity-induced Lorentz violation.
