Enhancement of the $\bar\nu_e$ flux from astrophysical sources by two   photon annihilation interactions
  The ratio of anti-electron to total neutrino flux, $\Phi_{\bar{\nu}_e}:\Phi_\nu$, expected from $p\gamma$ interactions in astrophysical sources is $\le1:15$. We point out that this ratio is enhanced by the decay of $\mu^+\mu^-$ pairs, created by the annihilation of secondary high energy photons from the decay of the neutral pions produced in $p\gamma$ interactions. We show that, under certain conditions, the $\Phi_{\bar{\nu}_e}:\Phi_\nu$ ratio may be significantly enhanced in gamma-ray burst (GRB) fireballs, and that detection at the Glashow resonance of $\bar{\nu}_e$ in kilometer scale neutrino detectors may constrain GRB fireball model parameters, such as the magnetic field and energy dissipation radius. 
Soebur Razzaque, Peter Meszaros and Eli Waxman