5-10 GeV Neutrinos from Gamma-Ray Burst Fireballs

A gamma-ray burst fireball is likely to contain an admixture of neutrons, in addition to protons, in essentially all progenitor scenarios. Inelastic collisions between differentially streaming protons and neutrons in the fireball produce $\num(\barnum)$ of $\sim$10 GeV as well as $\nue(\barnue)$ of $\sim 5$ GeV, which could produce $\sim 7$ events/year in km$^3$ detectors, if the neutron abundance is comparable to that of protons. Photons of $\sim 10$ GeV from $\pi^0$ decay and $\sim 100$ MeV $\barnue$ from neutron decay are also produced, but will be difficult to detect. Photons with energies $\lessim 1$ MeV from shocks following neutron decay produce a characteristic signal which may be distinguishable from the proton-related MeV photons.