Atmospheric Neutrinos, GeV to PeV
Atmospheric neutrinos are of interest as a beam for the study of neutrino properties and as a foreground in the search for astrophysical neutrinos. An accurate understanding of their flux is important for both. Uncertainties in the flux of atmospheric neutrinos arise from composition and spectrum of the primary cosmic radiation and from imperfect knowledge of hadronic interactions. Both aspects will be addressed, including constraints from measurements of atmospheric muons.