Atmospheric Neutrino Flux: A Review of Calculations

The concept of using the atmospheric neutrino beam to look for neutrino oscillations is illustrated in Fig. 1 [1]. With a single detector it is possible simultaneously to cover a range of pathlengths from ∼ 10 to ∼ 10 km, corresponding respectively to downward moving and upward moving neutrinos. The atmospheric neutrino beam has an energy spectrum determined by the steeply falling primary cosmic-ray spectrum, which generates the neutrinos by interactions of the cosmic ray nucleons in the atmosphere. Examples of calculated neutrino fluxes are shown in Fig. 2.